Diana 75/Beeman 400 recoilless target air rifle: Part 4

by Tom Gaylord
Writing as B.B. Pelletier

Diana 75
The Diana 75.

Let’s make lemonade
Part 1
Part 2
Part 3

History of airguns

This report covers:

  • Three groups
  • Taped the targets
  • Hand-held
  • Follow-through
  • Glasses
  • First group — H&N Finale Match Light
  • Group two — RWS R10 Match Pistol
  • A secret
  • Head sizes and groups
  • Group three — Vogle Match pellets
  • Velocity?
  • Why?
  • Another accuracy test

Today we revisit the Diana 75/Beeman 400 for a very special reason. You readers thought the rifle didn’t perform up to expectations last time in the accuracy test, and neither did I. So I took every one of your recommendations and applied them today.

Three groups

I only have three 5-shot groups to show you from today’s test. I shot them with the two pellets that did the best in the last test, plus one pellet that I thought might be on the fence. I shot from 10 meters and I’ll tell you the rest as we go. Much of what I will say in this report is for me, for the next time I shoot this rifle.

Taped the targets

To keep the targets from tearing I put tape on their backs. I used aluminum foil tape like Hank recommended on some of the bulls and a white form of duct tape on the rest. The aluminum tape tore the target paper around the edges of each hole and was not as clean as the white duct tape, so next time the white tape is what I’ll use. Just cover the back of each bull and that’s it.


Someone, I don’t know who, recommended holding the rifle tight to the shoulder. He said the Giss contra-recoil system does not like to be rested directly on a bag. Maybe that was a comment to the Diana 10/Beeman 900 pistol that I tested awhile back. Either way, today I rested the forearm on the flat palm of my off hand that was resting on the sandbag. I did not grip the forearm with my fingers. I also pulled the butt firmly into my shoulder and my right hand gripped the pistol grip of the stock firmly.


Another person said my groups last time looked like I wasn’t following through. I had to agree with him. I made a concerted effort to follow through on every shot this time.


Instead of the 1.25-diopter reading glasses that I would normally use, I wore my regular glasses today. My vision is 20-25, corrected to 20-20 by my glasses. The front sight diopter was clear and I was able to center the bull precisely.

Okay, that’s a lot of stuff done differently than last time. Last time the rifle was rested directly on the sandbag, the targets were not taped, I wore the reading glasses and I held the rifle in a classic artillery hold. I also agreed that I was probably not following through on every shot last time. So all the important stuff was changed today to conform to the comments made by you readers.

First group — H&N Finale Match Light

In the last test I thought that H&N Finale Match Light pellets did the best. When I measured the groups I discovered that a different pellet beat them, but I still had a very good feeling about this pellet. The best group with Finale Match Light last time was five in 0.186-inches between centers.

Today I put five Finale Match Light pellets into 0.14-inches between centers. That is a gold dollar group, because it’s smaller than 0.15-inches between centers. It’s also the best group of the day — or at least the best group that I will show you.

Finale light group
The Diana 75 put five H&N Finale Match Light pellets into a 0.14-inch group at 10 meters.

This group was high, so I adjusted the rear sight down 9 clicks. I can’t hear the clicks when I adjust, but the numbers on the scale tell me what I am doing.

Group two — RWS R10 Match Pistol

The next pellet I tried was the RWS R10 Match Pistol wadcutter. In the last test this pellet did the best, putting five into 0.162-inches at 10 meters. This time it didn’t group as tight, with five in 0.198-inches, but that’s still good enough for the silver trime (groups that are less than 0.20-inches between centers).

R10 Pistol group
The Diana 75 put five RWS R10 Match Pistol pellets into a group that measures 0.198-inches between centers at 10 meters.

A secret

And now I’ll tell you a secret. I didn’t shoot just three groups this time. I shot four! The first group of R10 pellets that I haven’t shown measured a tight 0.121-inches between centers — BUT, there is also a lone shot that hit about a half-inch to the left of the group. I believe on the last target that I am about to show you I might have fired one of the five shots at the wrong bull and it was the flier I just mentioned with this first R10 group. I believe that, but I’m not sure. 

I looked at the small R10 group through the spotting scope after completing it and I didn’t see a hole off to its left, but when I collected the target there it was. And, on the next group you are about to see, I can only see what appear to be four holes. Also, the wild shot on the R10 bull would have grouped with the rest of these other pellets, had it been shot at the correct bull.

I’m not showing you that smaller R10 group because I don’t know for sure what happened. But I saw the small group clearly through the scope and I believe I would have also seen the stray hole if it had been there. Hey, guys — this is what happens in the real-world!

Head sizes and groups

Jerry Cupples and I had talked for a long time the day before about Pelletgage and I had pellet head sizes on my mind. I just bought 6,500 Vogel target pellets that came in a bulk pack. They can be any head size and I suspected this Diana 75 likes the larger sizes. So I checked the head sizes of both the Finale Match Light pellets and the R10 Match Pistol pellets. I didn’t sort them by head size — I only wanted to know what their general head sizes were in the tin, since they were the two most accurate pellets in this rifle.

Finale Match Light pellets had head sizes that ranged from 4.525 to 4.53mm and R10 Match Pistol pellet heads ranged from 4.515 to 4.525mm. I’m using a special Pelletgage that Jerry produced that goes down to the thousandth of a millimeter.

Then I hand-sorted 11 Vogle pellets with head sizes greater than 4.53mm. I know that is a larger head size than the other two pellets, but at the time I thought bigger was better in this rifle.

Group three — Vogle Match pellets

This group, which may only be 4 shots (it was backed by aluminum tape), measures 0.547-inches between centers at 10 meters. Clearly, and in comparison with the other two (or possibly three) groups, the Vogle is not the right pellet for the Diana 75 — at least not Vogels with heads larger than 4.53mm!

Vogel group
Either four or five Vogle pellets made this 0.547-inch group at 10 meters. I think the Diana 75 does not like pellets with a head size larger than 4.53mm, and it may not like Vogel pellets altogether.


Now I will address something several readers mentioned after they read the velocity test in Part Two. They wondered whether the new piston seal that Dave Slade installed in the rifle a few years ago was still breaking in. You may remember that the former owner of the rifle sold it to me knowing that the velocity was slow. Those readers who commented wondered whether the rifle might speed up as that new seal was used.

Well, between Parts 3 and today I have shot the rifle another 60 times since the velocity test was done. If there is some break-in happening we should start seeing it by now, I think. So I shot another string of 10 RWS R10 Match Pistol pellets for velocity. 

The average for this pellet in Part 2 was 534 f.p.s. The low was 526 and the high was 543 f.p.s., so the spread was 17 f.p.s.

Today I oiled the piston seal with two drops of silicone chamber oil, then fired 9 shots to settle down the powerplant. When oil stopped spraying out on every shot, I started the chronograph. The average today was 545 f.p.s and the spread went from a low of 539 to a high of 551 f.p.s. — a difference of 12 f.p.s. After 60 shots since the last velocity test the average velocity for this pellet is up by 11 f.p.s. and the spread is down by 5 f.p.s. It’s a small difference but it does appear that the new piston seal could be breaking in. I plan to watch the velocity of this rifle over time and see how it develops.


Why did I run this extra accuracy and velocity test? I did it because in the future I want to pit this rifle against my FWB 300S that is the most accurate 10-meter rifle I own. I learned a lot today, and I have explained all of it to you in this report.

This rifle came to me with a test target group that measures 0.065-inches between centers. As far as I’m concerned, we have not yet seen performance of that level from this rifle. That means one of two things, or both. Either I haven’t yet found the right pellet for the rifle, or I haven’t yet found the right head size. I think the ideal head size for this rifle is around 4.52mm. Based on the smallest group of R10 pellets that I didn’t show you, the group that might measure 0.121-inches between centers if I’m right about the flier, the R10 may be the best pellet and 4.52mm may be the correct head size.

The test target that came with the Diana 75 is serial-numbered to the rifle. A group of five pellets are in 0.065-inches at 10 meters.

Another accuracy test

I see another accuracy test is in store for this rifle. I want it to do its very best when it faces my FWB 300S, because that rifle certainly will be doing the same.

Grandpa guns

by Tom Gaylord
Writing as B.B. Pelletier

This report covers:

  • Things to consider first
  • Red Ryder
  • Start with open sights
  • Fun!
  • Other grandpa airguns
  • Crosman 760
  • Daisy 880
  • Daisy 35
  • Lawyer triggers
  • Breakbarrels
  • BB — what about CO2? What about a repeater?
  • Over to you

Today’s report will be near and dear to many of you. What airguns does a grandpa need, so when the grandkids come over he has something fun to do with them?

When I was a boy, both my grandfathers were so much older that they didn’t really play with me at all — at least not that I remember. But watching guys these days, I see a big difference. Grandpas are fun guys! Well, airguns are fun and every kid wants to shoot — the girls just as much as the boys. So, what airguns can grandpa have that will be fun for the grands when they come bye?

Things to consider first

Long guns are the best way to begin. They are safer because grandpa can watch the muzzle easier and stop the kids from making dangerous mistakes. 

Some kids want to keep their fingers on the trigger all the time. Grandpa has to discourage this by taking the gun from them and explaining how dangerous it is. Each kid is different and grandpa should know how far to trust each one.

Single shot rifles are the best way to start a kid. That way you can coax the “spray and pray” mentality out of them before it becomes ingrained. Video games often do just the opposite, rewarding the fast trigger finger, so you have to battle that. If the kids will listen to you, get them started talking about making good shots.

When I trained junior marksmen the key was to get the kids to focus on hitting the exact center of the bull, rather than just pulling the trigger and hoping the shot was somewhere in the black. Each kid is different and you have to learn right away whether they are listening to you or not. In marksmanship training we used to not let them touch the gun until they could explain a good sight picture and respond to basic safety commands such as “cease fire.”

Grandpa shouldn’t be a safety Nazi, but he should insist on safe gun-handling practices before allowing the shooting to continue. This is an important responsibility — especially when one or both parents are impulsive and careless. Do it right and the kids will soon be correcting the adults.

Red Ryder

If I don’t put the Red Ryder down I’ll hear from you readers. Yes it is a good gun to use with grandkids, but being a BB gun you need to take some extra safety precautions. A BB gun in this class is shot at very close range and those BBs have a way of bouncing back and hitting the shooter. So — eye protection for everyone in the vicinity.

The good thing about the Red Ryder is it’s lightweight and relatively easy to cock. It’s a repeater, so the little guys and gals won’t get frustrated too soon. Shoot at targets that react for the greatest enjoyment. Balloons are a lot of fun, and the common tin can is the number one target of choice, with the feral aluminum soda can being the current high-tech favorite. Plastic army men are another good choice to sharpen the eye!

I said it’s relatively easy to cock, because for a small kid cocking a Red Ryder can be a challenge. This is where Grandpa steps in and shows the youngster the right way and the safe way to cock the gun. It is also self-limiting. The youngster will tire more quickly if he or she does the work, which is as it should be.

Start with open sights

Unless the child has a serious vision problem that precludes it, start them with open sights. Don’t graduate to a scope until they are proficient with opens.

I will put in a plug for the Daisy 499B here. It is a wonderful training tool that teaches the use of non-optical sights and may bring out a young William Tell or Annie Oakley.

499 sight picture
The Daisy 499 is a natural to teach a proper sight picture.

499 target
Yes, there are 10 shots in this 5-meter target. When youngsters apply themselves they can learn to do this offhand with a 499B in a few years.


Okay, BB got away from today’s topic just a little. This is supposed to be about fun — not work! Sorry, but I have seen too many kids who had the potential to become great shooters after just a few hours of instruction! But we’re interested in grandpa-fun today.

Other grandpa airguns

I’m not listing these in any order of preference. But I will mention the benefits of each gun as we go.

Crosman 760

Crosman 760https://www.pyramydair.com/s/m/Crosman_760_Pumpmaster/339

Crosman 760 Pumpmaster.

The Crosman 760 is a single-shot multi-pump gun that shoots either pellets or BBs. When it shoots BBs it is a repeater. For pellets it’s a single-shot.

This airgun is a smoothbore, so the accuracy isn’t going to be good at long range. I did get one good group of H&N Finale Match Light pellets, but I’m betting grandpa isn’t going to spring for pellets that cost $17 a tin. I did find the 760 accurate with RWS R10 Match Pistol pellets, as well, but the price is the same. It did okay with Hobbys, too, so either start with them or with Crosman wadcutters.

The 760 also did its best with H&N Smart Shot lead BBs at 5 meters. That’s a blessing because Smart Shot BBs are lead and don’t bounce back like steel BBs.

The 760 is reasonably lightweight and it also pumps fairly easy, so it’s a great airgun for older kids. It’s not for the youngest ones, but when they start growing, this is one to consider.

Daisy 880

Okay, we have now heard from Pepsi — what about Coke? Daisy’s 880 is another fine gun for grandpa. It too shoots both BBs and pellets. With BBs it’s a repeater and with pellets, a single shot. I did even better at 10 meters with the 880, shooting Hobbys and some obsolete Daisy Superior Match Grade wadcutters. And the 880 is rifled!

Daisy 880
Daisy’s 880 has a rifled barrel!

I did test the 880 with BBs, and Daisy also sent the target they shot that showed 5 Daisy BBs in 0.65-inches at 5 meters. It’s no 499 but it’s pretty good! I put ten Daisy BBs into 0.624-inches at 5 meters. So, grandpa, the 880 is a great little gun for the kids.

Unlike the Crosman 760, the 880 has a rifled barrel. That’s why it’s a little more accurate 10 meters. It’s also lightweight and easy to pump. There are several related air rifles when you search on the 880. Many are kits that have additional items besides just the rifle. These kits come and go too fast for me to address, but at their heart is the 880 rifle.

Daisy 35

Daisy’s model 35 is another good grandpa gun. It’s a multi-pump that shoots both BBs and pellets. So, how does it differ from the 880. Well, the pump handle is a short stroke instead of the 880’s longer stroke. In other words, it’s more like the Crosman 760. It’s also a smoothbore that shoots both BBs (as a repeater) and pellets (as a single shot.

Daisy 35
Daisy 35.

The 35 I tested back in 2012 and ’13 did not-so-good with BBs and very good with pellets. I liked it so much that I ordered another one for another test in the near future.

Like all the airguns we’ve seen so far the Daisy 35 is lightweight and easy to pump. But is does have one drawback that all the other airguns I’ve mentioned share.

Lawyer triggers

For some reason airgun manufacturers cannot put out a youth airgun with a decent trigger. I think the reason is simple. These guns all compete on price. They sell them in the big discount stores where most people shop by price and not features. All these airguns have variations of direct sear triggers. Putting a killer trigger on a $35 air rifle would add $5 to the price and make 300 sales to informed customers, while loosing 30,000 sales to moms and dads who only look at the price tag. So the lawyers have their day and I have to agree with that logic. Unless there is a caring grandpa or grandma who is willing to spend the time to train little Bobby and Susie on the right steps of gun handling, give them their lawyer triggers!


Now let’s take a big step up to the next level of kids airguns. I’ll start with the Ruger Explorer. Many of you can tell that it is a less-expensive version of the Umarex Embark. Both are breakbarrel spring-piston air rifles that are reasonably lightweight and cock easily. They are well-suited to children that are old enough to hold them offhand and cock them while standing up. I’m not giving ages now because boys and girls develop at their own rates over time. I wrote a 5-part report on the Embark and got superior accuracy from it at 10 meters. I’m guessing the Ruger can do just as good. Gramps — this one will make you a hero!

The Ruger Explorer
The Ruger Explorer.

BB — what about CO2? What about a repeater?

Well, sure. Repeaters can be great fun and CO2 is an inexpensive way to get one. My pick in this category is the Crosman 1077. And, I see that Crosman has brought back something that we have been asking for for years — the 1077W with a wood stock!

Now, you can get a regular 1077 for $40 less than the one with the wood stock. You’ll still be a hero if you do. But the wood one is the one you personally will be proud to own.

Crosman 1077 walnut
The 1077 wood!

All right you tire-kickers! Off the couch and get online to buy that rifle you all said you wished Crosman would bring back. Because — here it is — the 1077 with a wood stock! Grandpa — what beautiful airguns you have!

There is one drawback for a 1077. It’s certainly light enough for anyone, but that trigger that operates both the clip advancement and the hammer cocking has a pull that’s too heavy for the little ones. After it breaks in with a few hundred shots it does become smoother and easier to pull, but at first the trigger pull is an obstacle for younger kids.

Over to you

Okay, Gramps, now you have your say. You know what works and what doesn’t. Tell the world!

A first look at a RAW: Part 1

by Tom Gaylord
Writing as B.B. Pelletier

The RAW field target rifle built on the new chassis frame.

This report covers:

  • The beginning
  • It’s here!
  • Scope
  • How does it shoot?
  • Results?
  • October 25, 2020 Chronograph
  • October 30 & 31, 2020 Chronograph
  • Accurate?
  • Pellets & Accuracy 
  • Summary

This report is a first look at a very special RAW. The RAW air rifle is manufactured by AirForce Airguns. It was formerly made in Tennessee and some work is still being done there, but the main manufacturing has moved to Texas.

RAW stood for Rapid Air Weapons before AirForce acquired the company. Since airguns are not considered weapons in the United States, AirForce has dropped the name, but they retain the acronym RAW because it is recognized to be at the top of the industry.

This report is about a RAW that was specially built for field target. It is built up on the new RAW aluminum chassis frame instead of residing in a wooden stock. It was built for blog reader Cloud Nine, who had a part to play in its design. He also gathered all the data and even wrote some of today’s report

The beginning

Cloud Nine (I’ll now call him Nine) is a field target match director at the Arlington Sportsman Club in Texas. He built his field target club up from scratch and it is now quite active in north central Texas. But he has been shooting in the spring-piston class. He wanted to get into PCPs, but was always waiting for the right rifle to come along.

After placing third in the 2019 AAFTA Nationals, shooting in the WFTA spring-piston class, Nine came to the attention of AirForce owner, John McCaslin, who wanted his RAWs to break into field target. RAW has made 12 foot-pound rifles before, but they were never optimized for the sport of field target. This was their chance to participate in the hands of a proven competitor who would feed back information on the performance of the rifle as he went.

It’s here!

Nine received his new .177 TM 1000 field target rifle in August and immediately set to testing and getting used to it. It was set up to shoot just under 12 foot-pounds, which is a requirement for the WFTF rules that govern his matches.

It has an aluminum chassis that functions as the frame and the forward part of the stock. It’s a single-shot with a sidelever to operate the bolt. The titanium reservoir fills to 250 bar (3600 psi) and the rifle is regulated. It has an adjustable buffer tube that incorporates a highly adjustable stock. It came with an adjustable buttpad that Nine exchanged for a RAW butthook. He also installed a Rowan Engineering adjustable forearm that FT shooters call a “hamster” and he added an ergonomic target pistol grip that he finds more comfortable.


Nine mounted a Sightron SIII FT 10-56X60 scope in Burris signature mounts that have a +/- 10 degree tilt that he adjusted down, of course. He uses a BKL dovetail-to-Picatinny riser to elevate the scope to his sighting eye. He has also mounted a thermometer to the scope to help figure out the scope shift as the temperature changes.

How does it shoot?

His first outing was August 25. Here is what he says, “I began testing the RAW TM1000 by determining the muzzle energy, to see how it varied and if any adjustments were needed to keep the rifle shooting below 12 ft-lbs.

Test 1………………RAW TM1000
Notes………………First test
Gun………………..RAW TM1000
Time………………..8:20 p.m.
Ext. Spread…………..23
Avg, Vel…………….783
Std. Dev……………..5.44
Avg. Energy………….11.7
Pellet wt………………8.44 gns.
Hi Vel…………………796
Low Vel………………773

RAW FT first test


The extreme spread was 23 f.p.s., which was larger than I expected, but the gun was new and would probably settle in to something more stable. In addition, even with this ES of 23 f.p.s., the gun still shot a 3/8-inch group at 25 yards when rested on a table, which is more than accurate enough for field target matches. At 50 yards, the gun was shooting a little more than 1⁄2-inch groups off a table, so I believe the observed ES had little effect on accuracy. This was a good finding.

October 25, 2020 Chronograph

After winning the first FT match that I shot in warm weather, I shot my next match in much cooler weather and noticed a large drop in Point of impact at 55 yards, and my scope zero of 27 yds. was also off. I re-zeroed the rifle at the sight-in lane, but didn’t quite figure out the new click chart for the change in POI at colder temps, so I didn’t shoot quite as well in that match. The next weekend, once again in cooler temps, I chronographed the rifle again.

Name………………RAW TM1000
Notes………………Rifle shot 3 MOA low (50X) at 55 yds. Chronoed the rifle and recalculated the click chart for 55 degreesF.
Gun…………………RAW TM1000
Time……………….9:46 a.m.
Ext. Spread………12
Avg, Vel…………..800
Std. Dev…………..3.55
Avg. Energy……..11.98
Pellet wt………….8.44 gns.
Hi Vel………………806
Low Vel……………794

RAW FT second test

October 30 & 31, 2020 Chronograph

I had the chance to shoot the next weekend in colder temps (40-47F) to ascertain velocity change and scope shift once again. The results were almost the same as they were at 55F, but the ES had dropped to 10fps. 


Nine was pleased with his new rifle’s accuracy, overall, but as he tested it he learned its peculiarities. Here is what he says, “I am convinced that the POI shift is not due to the gun changing velocity. It could be related to air density increase in the colder weather and scope shift. I will have to investigate more thoroughly as I learn this rifle. I did measure a scope shift due to temperature. I setup my yardage markers at 85F in September, and now in October at 45F, the scope ranges 3 yards short at 55 yards.”

Pellets & Accuracy 

“You will notice that I changed pellets from AA 8.44gr to JSB 8.44gr because I noticed that the AA’s weren’t grouping as well as I expected. In fact, they were grouping no better than about an inch at 55 yards. I used a PelletgageR to measure the heads on the AA’s and they were almost all 4.49mm, with a few 4.50mm, so the head sizes were very consistent, but also on the small side, I believe. I measured the JSB head sizes, and they were all 4.50mm to 4.51mm, so just a little bigger.

“The slightly larger head size of the JSB seemed to help reduce the group size. I hadn’t started holding the rifle with a firm hold as I will describe now, so these groups @ 27yds might get a little smaller with a firm hold.”

RAW FT PelletgageR
PelletgageR was used to rapidly sort pellet heads.

I also noticed that group sizes were affected by how I held the rifle — a light grip with rifle resting on the hamster versus a firmer grip with rifle resting on hamster, my hand on the hamster, and the butt pulled into my shoulder with a good cheek weld. The firmer grip, which is the way I shoot the rifle in matches, resulted in best group sizes, so I captured a 60yd group below to verify. 

I shot at the range with Cloud Nine as he was learning his rifle and I was present on the day he learned that the JSB 8.44-grain pellet was superior to the Air Arms 8.44-grain pellet that Martin Rutterford, the former owner of RAW, had recommended. I am skipping past bushels of targets and data he gathered between field target matches.

RAW FT Cloud Nine
Cloud Nine on the windy day he learned that JSB 8.44-grain pellets with 4.51mm heads are the best in his rifle.

A 13-shot group at 50 yards with Cloud Nine’s new RAW field target rifle.

RAW FT 60 yards
After learning the right pellet and the hold, Cloud Nine’s RAW put nine pellets in 0.630-inches at 60 yards.


This is just our first look at Cloud Nine’s field target RAW. He has made several reports to AirForce regarding things he would like to see on the rifle, and they are talking to him at length. As I told you I have bypassed bushels of targets and data to give you this quick look at a RAW field target rifle that currently only exists as a work in process. It’s a work that has won several field target matches so far, so it is a labor of love for the man testing it.

Does seating pellets extremely deep help?

by Tom Gaylord
Writing as B.B. Pelletier

This report covers:

  • The rifles
  • The test
  • El Gamo David
  • Discussion David
  • Diana model 35
  • Discussion Diana 35
  • Diana 27
  • Discussion Diana 27
  • Summary

Recently a reader posted a comment that he had improved his accuracy by seating pellets extremely deep into the barrel of his airgun. He said he pushed them in 40mm or more. So today I conducted a test to see what affect, if any, that has on a couple of my rifles.

The rifles

I selected the El Gamo David because we just saw it shoot. And I selected the Diana 35, which is a very accurate breakbarrel I last tested June of 2019. Then I researched both rifles and selected the best pellet from all my testing and also the best hold for each airgun.

The test

I shot off a rest at 10 meters. I shot 5-shot groups so I wouldn’t tire out in the middle of the test, but also so I could concentrate on my technique.

To seat the pellet deep I used an Allen wrench with 40 mm marked off on the shaft. I pushed the pellet into the bore until that mark was flush with the entrance to the breech. The reader who commented said there wasn’t any magic about 40 mm, it was just his way of telling us about how deep they were seated. And 40 mm works out to 1.5745-inches, in case you wonder.

The Allen wrench seated the pellets to about 40 mm deep.

El Gamo David

The El Gamo David shot best with RWS Meisterkugeln Rifle pellets. In Part four I put 5 of them into 0.166-inches between centers at 10 meters, resting the rifle directly on the sandbag. I shot the David first the way I did in Part 4 — seating each pellet with a ballpoint pen. The first shot hit the target to the right of the bull, but I continued to shoot the group anyway. Five pellets landed in a group that measures 0.607-inches between centers. It’s much larger than the group I shot in Part 4, so I will keep an eye on my shooting technique.

David Meister Rifle pen
When the pellet was seated with a ballpoint pen, the El Gamo David put 5 RWS Meisterkugeln Rifle pellets in 0.607-inches at 10 meters.

I was surprised that the group was as large as it was, given what the David did just last week, but maybe the group was more of an indication how well I was shooting — not the rifle.

Now it was time to seat the pellet deep. I started each pellet with the pen to get the skirt into the barrel, then pushed it in with the Allen wrench to the mark on the shaft. Then I shot each pellet just as carefully as before. This time five Meisterkugeln Rifle pellets went into as group that measures 0.648-inches between centers at 10 meters. It’s not much different and certainly no better than the first one.

David Meister Rifle 40mm
When the Meisterkugeln Rifle pellet was seated 40mm deep in the bore five of them went into 0.648-inches at 10 meters. This group is also a little more to the right than the last one.

Discussion David

So the El Gamo David didn’t do much different with the deep seating. Given the extra work that’s involved, I think this procedure is not for this air rifle.

Diana model 35

Next to be tested was the .177-caliber Diana model 35. This rifle delivered remarkable accuracy when I last tested it in June of 2019. It likes Air Arms Falcons the best of all and back then it gave 10-meter 5-shot groups that ranged from 0.194-inches to 0.371-inches between centers.

I first tested it with the pellet seated flush and using the artillery hold with my off hand at the rear of the cocking slot. Five Falcons went into 0.25-inches at ten meters. Not only is that a great group, it also proves that old BB can still shoot. And, it is in the range of this rifle’s accuracy with the same pellet a year and a half ago.

David Falcon flush
The Diana 35 put 5 Falcon pellets in 0.25-inch group at 10 meters when seated flush.

Next I used the Allen wrench to deep-seat the Falcons 40 mm into the bore. This time, using the same artillery hold the Diana 35 put five Falcons into a 0.836-inch group at 10 meters. This time the difference between seating flush and extra deep is decisive!

Diana Falcon 40mm
When seated 40mm deep, the Diana 35 threw the Falcon pellets into this 0.836-inch group at 10 meters.

Discussion Diana 35

I was so glad to see that I was shooting okay. This is why it’s nice to have an air rifle that always delivers. Also — never sell an accurate airgun!

At this point in the test I had one result that was inconclusive and one that was decisively against seating 40mm deep. So I shot one more rifle.

Diana 27

This rifle is my Hy Score 807/Diana 27 in .22 caliber. I used obsolete Eley Wasp 5.6mm pellets for the test. First I shot five Wasps that were seated flush with the breech. They made a group that measured 0.555-inches between centers at 10 meters. They also struck the pellet trap noticeably louder!

Diana 27 Wasp flush
The Diana 27 put 5 Wasp pellets that were seated flush into a 0.555-inch group.

Now for 40mm deep-seated pellets. This time the Diana 27 put five Wasps in 1.207-inches at 10 meters — a definite degradation in accuracy!

Diana 27 Wasp 40mm
When seated 40mm deep the Diana 27 scattered five Wasps into 1.207-inches at 10 meters.

Discussion Diana 27

These three little tests are not conclusive, but they do indicate that seating a pellet 40mm deep in the barrel doesn’t help — at least not with these three rifles. It was such a bizarre idea that I just had to know for sure. If the reader who told us about this would like to write a guest blog and expand on what I have done here, he is certainly welcome.


When the idea of seating 40mm deep was first mentioned I didn’t like it because of the lack of cushioning the piston would get. However I did listen closely during this test and couldn’t detect any difference in the shot cycle.

At least we gave it a try!

What’s it gonna be today?

by Tom Gaylord
Writing as B.B. Pelletier

History of airguns

This report covers:

  • The beginning
  • Walther LGR
  • Diana model 10
  • What is a Diana 10?
  • The grips
  • The top spacer
  • Sights
  • Trigger
  • Power
  • Summary

Today is a special treat. We are going to go back into my distant past and see something that was pivotal in my life. It was, and yet this one wasn’t. This is something that made me the airgunner I have become, and I have been telling you about it on this blog for many years. I have and yet I haven’t. Read on, Grasshopper.

The beginning

The year was 1976 (I think), and I was walking with my first wife and son through Rothenburg ob der Tauber — a walled medieval town next to the Tauber river in northern Bavaria, Germany. Rothenburg is a tourist town today, because it is so well preserved and colorful. I enjoyed going there with my little family on my time off and just walking around seeing the sites!

One day, however, something different happened. Up a side street I saw the sign for a gun store. Now, ANY gun store in Germany would catch my attention, but one in Rothenburg just had to be special, like everything else in that quaint old town. So, we wandered in and looked around.

Walther LGR

The owner spoke good English, so there was no problem communicating. And he saw right away that I was a gun guy. So all barriers came down. He saw my eyes alight on a Walther LGR target rifle, which he brought down and handed to me. It was the first 10-meter air rifle I had ever seen! I was blown away, and the owner could see it. When he told me how the gun was charged to shoot I was even more flabbergasted. I think he was, too, and he just wanted to show off his special toy. If you want to see what I’m talking about, read this three-part report.

But like I said — I was a family man with a young family. I didn’t have the kind of money the LGR was commanding, and although I had a credit card I had learned by that time that the bills always come due. So — looky and even touchy but no takey home.


Then I spotted a brown leather briefcase in one of his glass sales cases. Inside, resting in bright yellow foam was an air pistol I had never seen. That one was every bit as exotic as the LGR, plus it had a price tag of less than half that of the rifle! This the family man could do (his wife said).

Diana model 10

That pistol was a .177-caliber Diana model 10 ten-meter target pistol. I didn’t know what 10-meter target was at the time, and it was just about a decade from becoming an Olympic sport (rifle in 1984 and pistol in ’88). Europeans had their matches going, but I was unaware of them.

The pistol, though, spoke for itself! And today I will let it speak to all of you. What I bought in that German gun store that day was a Diana model 10. But Robert Beeman sold it as the Beeman 900. It was at the top of a line of Dianas that Beeman Precision Arms once sold.

Diana 10
This is what a Diana model 10 pistol looks like in its case.

The gun I recently purchased from an estate and am testing for you now wasn’t marked as a Diana model 10. It was marked as a Beeman model 900. And there was no case, no manual and no tools.

Beeman 900 marks
This is how the test pistol is marked.

According to the Blue Book of Airguns (the new edition of which will be available again before the end of this year — stocking stuffer), The first model 900s were marked Beeman’s Original Model 10. “Original,” if you remember your airgun history, is what the German Diana company had to mark their guns for a time after WW II, because Milbro in Scotland was awarded the rights to manufacture airguns using the Diana name.

So, Beeman sold it as a model 900. They also sold the Diana model 6 that was closely related as their model 800 and the 6M target configuration that was even closer as the model 850. But their 900 is a Diana 10, The same as that 10 I bought in Rothenburg.

What is a Diana 10?

The Diana model 10 is a 10-meter target pistol from the 1970s. At the time it was in competition with the FWB model 65 and Walther’s LP 3. The 10 is a breakbarrel spring-piston target pistol that uses the Giss counter-recoiling pistons to cancel recoil. You feel a pulse of energy with the shot but no movement from the gun. 

This is the air pistol I used to convert my gun-hating father-in-law from California into an airgunner. That story is worth reading if you have the time.

The earliest model 10s had a lump at the muzzle end of a synthetic spring-loaded barrel jacket. The shooter pulled the jacket forward and rotated it 90 degrees until the lump was above the front sight. The lump was your hand’s protection when you broke the barrel to cock the pistol. It sounds awkward, but after 10 shots everyone becomes a pro.

Beeman 900 lump down
The lump is down most of the time.

Beeman 900 lump up
Rotate the lump up to protect your hand when you want to cock the pistol.

The grips

The grips are a set of walnut panels with a palm swell on the right side. The palm shelf at the bottom of the grip slides up to make the grip tight, because 10-meter competition is shot with one hand, only. The shelf can also be tipped up in back to make it even tighter and the Diana 10 grip has a feature I have never seen on another 10-meter pistol. Believe me — I have looked!

Beeman 900 grip
The Diana 10 /Beeman 900 grip is extremely adjustable to grab the shooter’s hand and hold it tight!

The top rear of the palm shelf can be slid back just a trifle to wedge into the shooter’s wrist joint, making this grip the most positive one I have ever felt. And I’m a 10-meter pistol shooter, so believe me — I have tried a lot of grips! But wait — there’s more!

The top spacer

There is also a spacer on top of the grip where the top of the hand touches the spring tube. This spacer pushes down on the top of your hand to make the Diana 10 grip the tightest one ever created! You don’t grab this pistol, you put it on. It can actually hurt to hold the gun for a full 60-shot match, but the gun is going nowhere your arm doesn’t allow. You don’t hold this pistol— it holds you!

The top spacer can be removed from the pistol, for those who can’t tolerate it. Or you can just adjust the palm shelf down until the grip is nice and comfy. The little shelf on the rear of the palm shelf doesn’t have to be deployed. Heck, you can even hold a model 10 with two hands if you want to blaspheme the sport of 10-meter pistol! But a hand that has to be massaged after a match belongs on a winner! Hoo-rrrrah!

Seriously, guys, 10 meter rifle shooters have an expensive fitted leather jacket and pants that bind them up like sausages. They can’t gain more than 5 pounds or this stuff no longer fits. They also have expensive shooting shoes, and a heavy leather shooting glove and kneeling rolls for their legs. All the leather is in “their colors.” They bring two cases on wheels to the competition — one for their rifle and the other for all their stuff.

Ten-meter pistol shooters show up in jeans and a tee shirt. That pistol grip is their one interface and believe me, it matters a lot to them!


Naturally the sights on the model 10 are adjustable. But they adjust in ways most of you have never seen. The front sight adjusts for width! Instead of different inserts, the sight swivels to be wider or narrower within the range of adjustment. Or take it off and there is another lower and skinnier blade waiting.

The pistol also came originally with several different rear sight notches. Install the one you like and then adjust the width of the front post to suit. Unfortunately someone has painted this front blade with orange phosphorescent paint! No doubt it was to see the front post better, but when the target is illuminated correctly in a match, a dark black post is best. I have to do something to fix it.

Beeman 900 front sight
By turning that front blade you change its width in the rear notch. Remove it altogether for a skinny front blade. Gotta get rid of that orange paint though!

Beeman 900 rear sight
This photo not only shows the rear sight, it also shows the top spacer that puts additional pressure on the hand holding the pistol. I believe it can be removed.


I know you want to know about the trigger, but I plan to cover it next time. It adjusts for first stage length, second stage weight and I think overtravel. The front of the blade also cants to the right, because this pistol is made for right-hand shooters. A left-hand grip does exist, so I have to believe the trigger blade face will also cant to the left.

Beeman 900 trigger
We’ll talk about the trigger adjustments next time, but you can see how many there are! I bet you all know what that one with the red sealant on it is! It’s the sear engagement! No touchie!


The Diana 10 is a powerhouse among early 10-meter pistols. I remember velocities in the 450-475 f.p.s. range. Unfortunately, Diana put in seals made from a synthetic material that degraded over time and all of them have to be replaced at some point. New seals should last a lifetime.

I was told that this pistol shoots in the 370s with RWS Hobbys, so it may need a reseal. That’s an expensive proposition because of timing the Giss system, so I will hold off as long as possible. We will find out more when we test velocity.


That’s it for our first look. There is more to see before we get to velocity, and after that we get to see the accuracy. I can’t wait!

How to mount a scope: Part 5

by Tom Gaylord
Writing as B.B. Pelletier

Part 1
Part 2
Part 3
Part 4

This report covers:

  • More scope stuff
  • Swap the rings
  • Spiraling pellets
  • What to do about spiraling pellets
  • Misaligned scope
  • How to correct the misaligned scope
  • Setting up a rifle
  • BB did NOT say all bundled scopes are bad!
  • Scope stiction
  • Sighting-in for one distance
  • Summary

More scope stuff

While we are finished with mounting a scope, there is more to tell. A lot of it does come to the forefront when you mount a scope, so it is germane to this discussion. We have touched on some of it before, but today I hope to tell you how to deal with it.

Swap the rings

This is a trick that can help resolve many of the problems we will see today. It’s also one of the big reasons that I prefer 2-piece rings to 1-piece. Someone asked last time what can be done when the scope’s axis is out of alignment with the barrel. Well, that is often the case. The way you find it out is — after you sight the rifle in you try to shoot at different distances and discover that your pellet is off to one side or the other. What can be done?

If you have 1-piece rings you can sometimes remove them and turn them around, so the ring that was in the rear becomes the front ring. I say you can do this only sometimes because you may be scoping a recoiling spring-piston rifle and you need the scope stop pin that’s built into one end of the mount. If that’s true you can always install a separate scope stop, but that pushes the whole scope mount forward and what does that then do to your eye relief?

With 2-piece rings you can make the same swap as the 1-piece, plus you can also turn either ring around — or both! We like to think that our scope rings are perfectly bored and aligned with their bases, and that’s often true, but when it isn’t it makes installing a scope a lot more difficult.

Spiraling pellets

Do pellets spiral as they travel downrange? I have seen them do it as I watched the target through a scope. I had bright sun behind me to reflect off the pellet skirt when this happened.

The pellet is traveling down range in a spiral path. Their movement is not caused by the wind. I ruled that out because of the tightness of the groups and because the wind was under 3 mph on the day they were shot. That leaves spiraling as the most likely culprit –- assuming I am right in my suspicions. For the sake of discussion, let’s say I am right and the pellets are spiraling.

spiraling pellets
This graphic portrays a pellet that spirals as it travels downrange. Even if you don’t see it through the scope you can see the results of it in the groups that are shot.

The only thing I can think of that would cause spiraling is an unstable (yawing) pellet that precesses around its axis in the direction of the spin. If you have ever seen a washing machine become unbalanced on the the spin cycle and hop around the floor in a certain pattern, you have witnessed the phenomenon of precession. Or, watch a top as it runs down.

pellet yaw

It has been known for over a century that bullets can precess. I believe it was discovered very shortly after elongated bullets were first used in rifled barrels. Years ago, I read an article in The American Rifleman about a test on the brush-bucking ability of a .30 cal. bullet. Once stability was disturbed by a stout branch, the bullet began to precess in the direction of twist in an ever-increasing spiral. Of course, that test is not the same thing that I’m discussing here, as the instability there was induced mechanically down range by the bullet striking a broomstick rather than yaw at the muzzle and differential air pressure. But it does show that bullets can travel in a spiral path.

Bullets (and pellets) can also be made unstable by their twist. Varmint shooters are aware that thin-jacketed bullets have been known to explode in flight from the centrifugal force of their spin. And tumbling, or more probably precession coupled with pronounced yawing, is well-known from the early days of the M-16’s development. I remember that a rifleman had little chance of hitting a man-sized target at 300 yards with early M16 rifles. The bullet design/twist rate combination had not been worked out correctly at that time.

With a right-hand twist, the precession spiral would be clockwise from the shooter’s perspective. I would also expect the spiral to enlarge as the pellet gets further from the muzzle.

Okay–so what does all this toffee-nosed drivel mean to real airgunners? It means that even if you correctly adjust your scope for trajectory, there’s still a big chance you won’t hit that half-inch kill-zone at 15 yards. Not because you’re too high or too low, but because you are too left or too right! If you’re throwing a spiral and your pellet isn’t centered on the line of sight at the range you expect it to be, you could miss.

What to do about spiraling pellets

Don’t shoot them! Find other pellets that don’t spiral, because they don’t all do it. If you can adjust the velocity, such as with a PCP, try that. My experience, though, is that if a pellet spirals from a certain airgun it tends to do it all the time, regardless of what you do.

Misaligned scope

Sometimes the optical axis of the scope is not aligned with the bore. This will give you similar results to the spiraling pellet, with some important exceptions. The first of these is the fact that the pellet will always be on one side of the centerline until it crosses over the line at some distance. Then it will remain on the other side. A spiraling pellet moves back and forth across the centerline.

misaligned scope
When the scope isn’t in line with the bore, this happens. It may be very subtle and difficult to see and the slant can go either way — to the left like this or to the right.

The second exception that the misaligned scope gives is the pellets fly in a normal trajectory. Pellets that spiral do so up against gravity as they fly downrange. The center of the spiral drops in the usual way but as the spiral widens, these pellets sometimes actually appear to be rising! You have to keep in mind that these pellets are actually flying on their own, due to low air pressure on one side. Thus they seem to defy the laws of physics.

How to correct the misaligned scope

There are a couple of things to consider here. First — is the scope base on the rifle the thing that’s misaligned? Reader shootski talked about having to correct a firearm that was drilled and tapped for scope rings in the wrong place. If that is the problem, you should first consider whether it’s worth the time and effort to correct. If it is, spend the time and money to do it right.

Once the scope base is either fixed or ruled out your next concern are the rings you intend to install. Are they worth it? A $10 pair of rings from the discount store can give you many of the problems we have just discussed. I own many dozens of rings, but I only use the ones I trust.

Once you have the rings you intend using, remember what was said about swapping them end-for-end and even turning them around individually if they are 2-piece. When you have exhausted all the repositioning options, consider using a different set of rings. I know this flies in the face of shooting on the cheap but which would you rather do — save money or hit your target? 

Setting up a rifle

You buy a new air rifle and there is joy in your castle! This new rifle will solve all your problems. It is infinitely accurate (whatever that means) and powerful enough to get the job done. Let’s say you stretched for this one and the new rifle cost you $280, delivered. But wait! You are not done. Figure another $100-150 for a decent scope — not a world-beater but also not one from the bargain barrel. Mounts will cost another $20-50, depending on the rifle and what you want to do. Your $280 investment just swelled to $400 to $480. That’s how much your new air rifle really costs! No wonder so many people swear by open sights!

Then, and only then, do you get to go through all the steps we have addressed in these five reports. Oh, and someone says, “That’s why I always buy the scope that comes bundled with the rifle I’m buying.” And do you also take delivery of that new $45,000 ATV with the tires they put on at the factory? Now, I know that remark is going to start a firestorm of controversy, or at least it should. Unless you guys don’t know tires!

If there is a lot of discussion about the tires, just substitute bundled scopes and scope mounts for tires and you will understand what I am telling you. Are all bundle deals bad?

BB did NOT say all bundled scopes are bad!

No, all scopes and mounts that come bundled with rifles are not bad. Let me give an example. The Sig ASP20 that’s bundled with the Whiskey 3 scope is a great deal! Yes, it does cost a lot of money, but it is a perfect example of you get what you pay for. It’s not a bundle where they are getting rid of scopes they can’t sell.

There are other good bundled scope deals. Look to the dealers who bundle — they seldom have warehouses of scopes to get rid of, and your loyalty means a lot more to them than it does to a manufacturer who looks to three or four major outlet chains as their primary customers.

Scope stiction

This is one you need to experience to appreciate. Some scopes resist being adjusted until they are jarred once or twice. These tend to be the less expensive scopes and they usually wind up on spring-piston rifles that have all the jarring they need. This failure to move to the new adjustment is called stiction. I’m not qualified to explain what it is, but I think it is a combination of static electricity and a weaker erector return spring — or a spring that is fully relaxed.

The solution to stiction is to bump the scope with the heel of your hand after every adjustment. Either do that or fire the rifle twice before firing for record. I wish I could tell you what to watch out for, but all I know is when a scope doesn’t have stiction it becomes one of my favorites!

Sighting-in for one distance

This is not about any special techniques or tricks. It’s just an eye-opener that we all need to be aware of.  When you sight in a scope for one distance, like 100 yards, and you leave it there you solve a large portion of all the scope problems there are. Canting is still an issue but all the stuff I’ve discussed today is moot.

It’s only when you want to use your scope at different distances that these things arise. And there is something you can do about it. Use the lowest power magnification you can get away with. I don’t expect you to shoot squirrels at 100 yards with a 2-power scope, but 6 or 8 power is much better than 32 power. Why? Because it takes your focus off minutia. It does what open sights do, only it also helps those whose eyes aren’t up to the task.

Field target competitors are an exception to this, so they need to set their scopes to work well between 10 and 50 meters. They could care less what happens at 60 meters, where a hunter has to care. The field target competitor has a harder job because of the range in which his scope must work, but at least there are boundaries.


I have addressed several concerns you readers have raised, plus a couple of my own. I will watch the comments to this report to see if any more in this series are required.

How to mount a scope: Part 4

by Tom Gaylord
Writing as B.B. Pelletier

Part 1
Part 2
Part 3

This report covers:

  • What optically centering DOES NOT mean
  • What optically centering really is
  • How to optically center a scope
  • Why do we do it?
  • Field target
  • Counting clicks — mechanical centering
  • Erector tube return spring
  • A better way
  • What about left and right?
  • Why so anal?
  • Pragmatic approach
  • Summary

Today we are going to discuss optically centering a scope. It’s going to be a difficult report for me to write, because the subject does not have much merit for airgunners. So I will compensate by adding some things that do have merit. Let’s go!

What optically centering DOES NOT mean

Let’s start with what optical centering DOESN’T mean. The optical center of the scope is not the place at which there are an equal number of clicks up and down and side to side. I say that and some of you already know it and yet the website “RifleOpticsWorld” has an online article written by “Rifle Optics Team” that says that setting a scope to the optical center is simply returning it to the factory setting. Excuse me????? 

Who in their right mind believes that a rifle scope comes from the factory set to its optical center? The factory assembles each scope as quickly as possible, checks it at certain points for quality and ships it. They don’t spend 45 minutes or more optically centering each scope they make!

This article then proceeds to tell the reader that optically centering is a solution to scope shift! No, it’s not! Optical centering has nothing to do with scope shift and it doesn’t fix it. I will tell you today what really does affect scope shift and how to correct it.

After reading this online article it is obvious to me that it was written by someone (or a team of someones) who was assigned to write it and they made stuff up as they went. If you understand what optically centering is, I invite you to read the article and see how far off the mark it is.

What optically centering really is

The optical center refers to the reticle and the field of view. An optically-centered scope shows zero reticle movement against a distant backdrop when the scope tube is rotated in a complete circle. Theoretically, it’s possible to achieve, but I’ve never seen it. The best I’ve seen is a reticle that moves about a quarter inch against a target 20 yards away when the scope tube is rotated in a complete circle.

How to optically center a scope

There are two ways to optically center a scope. The first way is to set the scope tube in Vee blocks and rotate the scope while watching the reticle against a distant target. I have done this with a quarter-inch dot as the target — set 20 yards from my position. Believe me — it can take a long time to get the scope pointing exactly at that dot — even with two people working at it! The easiest way I have found is to put a large white sheet of paper at 20 yards distance and talk a friend into drawing the dot, while you look through the scope that’s sitting in the Vee blocks and direct him. I initially thought the precision of the Vee blocks mattered, but I’ve since recognized that you can use a cardboard box with two Vee grooves cut in the right place to support the scope tube. It’s not the blocks that give the precision; it’s the fact that, other than rotating on its axis, the scope never moves..

Now, rotate the scope tube in the Vees and adjust the reticles until both lines remain centered on the dot. On a good day with some luck this takes about 45 minutes to get as close as you are going to get and the reticle will still move off the dot in a few places in its rotation, i.e. the intersection will move in and out of the dot as the scope rotates.

The second way to optically center the scope is to stand the objective lens on a mirror in a well-lit room or even outdoors in bright sunlight. Look down through the scope and what do you see? If the reticle appears blurry or doubled, adjust it until all you see is one sharp reticle. In other words, the real reticle is on top of its reflection. This way sounds easier than the first method because it is. But it doesn’t give results that are any better than the first method and maybe not as good. You see, the glass on the mirror is not parallel to the reflective surface on the back of the mirror, and you will always be off by some small amount.

mirror technique
With the scope’s objective resting on a mirror, adjust the horizontal and vertical reticles until the heavy reticles are covering the shadow lines — as best you can.

Why do we do it?

The belief is that once the scope is adjusted to its optical center it can then be mounted in an adjustable scope mount and, without changing the elevation or windage knobs, zero the scope at an ideal distance by adjusting the mount, only. You will have to use a scope mount that adjusts in both directions to do this. Having done this several times I can tell you that it is absolutely impossible to do. But, for the sake of argument, let’s assume it can be.

Once the scope is optically centered and also zeroed, you can then adjust the scope’s elevation reticle for range changes to your target. Because the scope is optically centered, the pellet will stay on the vertical reticle at all practical distances. Let me give an example.

Field target

You have optically centered your scope and then zeroed it at 20 yards by adjusting the scope mount. You are shooting a .177-caliber pellet at 900 f.p.s. You will be on target from 20 yards to about 24 yards and then your pellet will start to rise above the center of the crosshairs. The pellet is not really rising, of course; it just appears that way to you.

From 24 yards to 28 yards the pellet rises until it is one pellet’s diameter above the center of the crosshairs but exactly in line with the vertical reticle. Starting at 29 yards until 32 yards the pellet will descend on the vertical reticle line but still be on the line, left and right. At 33 yards the pellet will start to descend below the center of the crosshair and by yard 35 it will be one pellet’s diameter below the center of the crosshairs.

dime and sight-in
This is the level of accuracy a field target competitor is seeking.

What you have just done is sight in an air rifle that is on target without any scope adjustment from 20 yards to 35 yards. You will be theoretically able to hold on the center of a kill zone on a field target within that range span and hit the paddle without touching the side of the kill zone — on all targets that have a 3/4-inch kill zone or larger.

All that I have just said is theory and it doesn’t work that way in the real world. In the real world the following is true.

1. It is impossible to optically center any scope. There will always be some slight movement of the reticle against a distant target as the scope is rotated through 360 degrees.

2. It is impossible to zero a scope with an adjustable scope mount. You can get close, but never exactly on.

Before we continue, let me define what I mean by exactly on. I mean the pellet is striking the point where the reticle lines intersect, with an equal amount of the pellet on either side of each line. This sounds anal, but the sport of field target makes shooters anal pretty quick. You see, there are kill zones that are smaller than 3/4-inches — some as small as 15 mm. When I competed in the late ’90s they were even smaller than that — down to 3/8-inch (9.44 mm). 

caliper and dime
This is the size (15 mm) of the smallest field target kill zone today.

If your pellet touches the side of the kill zone while passing through it can push the target “face” backwards hard enough to lock it upright, even though the paddle has been hit. The target won’t fall and you won’t get a point. This is the reason field target shooters are so concerned with accuracy.

Once when I was competing, one of the shooters brought his friend to the match to try it. He was a SWAT sniper and was confident he would do well. I think he thought he would teach us all a lesson in how to shoot. He finished in the middle of the pack of about 20 shooters and when it was over he told us that he was trained to shoot someone in the middle of their head. He reckoned that field target shooters would aim for one particular hair on the head — which is just about the case.

Counting clicks — mechanical centering

I hope I have made my point why optically centering a scope is impossible. Later on I’m going to tell you a very practical way to get the result that people desire from centering, but right now let’s discuss mechanical centering.

When you center a scope’s adjustments mechanically you are finding the spot in both adjustment where there are an equal number of clicks in all directions. If there are 123 clicks down there have to be 123 clicks up. Same for left and right, though they may not be the same number of clicks left and right as up and down. But don’t worry — it doesn’t matter, and here’s why.

Erector tube return spring

The reticle lives in the erector tube and the lines never appear to move when adjusted. That’s because they don’t. The entire tube moves while the lines remain stationary. Yes, there are European and Russian scopes whose reticle line actually do move, but they are an exception and not a part of this discussion.

There is a spring that’s mounted on a 45 degree angle to the erector tube and across from bothe adjustment knobs. It pushes back against both the vertical and right adjustments to keep the erector tube in whatever position the adjustments have put it. To the shooter it looks like nothing has moved.

At some point this spring gets relaxed and doesn’t push as hard. Then the tube can move without being adjusted — as in when it is jostled or bumped. That is when the scope starts to lose its zero and shifts randomly. So, centering the reticle (erector tube) mechanically doesn’t make much sense. Yes there may be 123 clicks on upward adjustment but the last 63 of them may be with the spring relaxed, so they are worthless. You don’t want to adjust the elevation there. Now that the scope is mechanically centered you have a lot of good downward adjustment that is useless (because you never adjust the scope that way) with very little upward adjustment before you start experiencing scope shift.

erector tube return spring
When the erector tube return spring relaxes, the erector tube starts moving on its own from vibration. Goobye zero!

A better way

Now I will tell you what really works and what top shooters around the world have discovered. Forget optical centering. Forget mechanical centering. Instead, adjust your scope until there is very little downward adjustment left. Once you zero the scope (with the adjustable scope mount) you will never use any downward adjustment. But you will use the upward adjustment, and this procedure has left a lot of it in the scope.

Everything I just said also applies to left and right adjustment, though it is not as critical. Gravity pulls pellets down; it doesn’t move them left and right.

What about left and right?

Okay, you understand how up and down works. What about left and right? Let’s assume that when you adjust the scope up the pellet stays glued to the vertical reticle. It never moves off the vertical line. It never does, but let’s pretend for a moment that it does. If you haven’t optically centered your scope, what happens when the farther out you shoot the farther the pellet strays to the left? 

Let’s also assume you are using a scope level for every shot, because none of this works if you aren’t. You notice that at 35 yards the pellet is half a diameter off to the left and at 45 yards it’s more than a full diameter off. What do you do?

What you do is check your zero at every 5-yard distance from 10 yards to 55 yards, because that is the distance at which you compete. Yes, I am aware the rules have changed and those distances are now stated in decimal fractions, but let’s keep this simple. And I said you check your zero every 5 yards and keep making small adjustments, but champions will then refine that to every yard — from 10 to 55 yards, or every meter from 10 to 50 meters.

What you do is adjust the left-right setting on your scope to get it as close to the centerline as possible at all distances. You never will get it perfect, but let’s say with careful work you get it to the place where your pellet is one diameter off to the left at 51 to 55 yards and one pellet diameter off to the right at 10 to 14 yards. It’s off by a lesser amount at the intermediate distances. Most field target competitors would be thrilled to have a scope that was that dialed-in.

Why so anal?

Do you really have to do any of this? Of course not. I don’t. You can go right on with your life, just as before. Nothing has changed. I wrote today’s report for those readers who were asking about optical centering. 

Pragmatic approach

The steps I have just given you (the last ones — the ones that really work) can take DAYS to complete! If you always want to see the bullseye get hit, watch a movie. This level of commitment to perfection is why some scopes cost more than $3,000 and some mounts cost over $500. You would be fooling yourself to think that serious competition can be done without a serious investment. Yes, you can follow these steps and do quite well on a budget, but remember — nobody races real cars in NASCAR.

My way is hard work. All the theory is out the window. As Jedi master Yoda told us, “Do, or do not. There is no try.”


In this article I have given you lots of things to do. But at their core there is one piece of invaluable advice. That is — it is impossible to do any of these things exactly. That applies to all of the procedures and desired results I have presented. You may think you are a perfectionist, but also recognize that for human beings there is no such thing.

You still should do your best to get as close as you can — so close that your hard work becomes a humorous anecdote that you can tell for many years to come, as I have just done for you!