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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.

Hand-held

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.

Follow-through

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.

Find a Hawke Scope

Glasses

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.

Velocity?

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?

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.

Diana-75-test-target
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.

29 thoughts on “Diana 75/Beeman 400 recoilless target air rifle: Part 4”

    • RR,

      I know that variety is the spice of life and trying different airguns is a lot of fun but I just can’t do that.

      By the time I (finally) decide on a particular rifle for a specific application; spend all kinds of time tweaking, tuning and customizing it; then shoot thousands of pellets “bonding” to it, I can’t see myself selling it. I would give it to a good home first.

      The FWB 300 is a sensitive subject – it took me 35 years to get one, I’m keeping it forever 🙂

      Hope you get an other one RR.

      Hank

      • Hank,

        Unless someone decides that their FWB300 should retire to RRHFWA, I do not see me getting another. I have four sproingers from 1906 through to the 60’s in that power range. I regret getting rid of at least one of the 300’s I had, but I have all these other ladies here to dance with.

        They went to good homes.

  1. B B,
    Since your 400/75 series commenced, I have managed to buy a newer 75U T01 variant that was overhauled a year or two ago but not used since. The gentlemen I bought it from was disposing of his Original Giss collection amongst some other match pistols and proved to be an honest and excellent seller.
    So far it has not managed to match my older 1980 example in terms of accuracy but and I also think it will take time to settle down/bed in. I have put less than 100 shots through it but have noticed improvements on the last couple of cards I shot. I plan to fall back on RWS Hobby/Geco until it its shooting accurately with these and then switch to R10’s/ Meisters, which the older 75 shoots very well. I wish you luck with yours and believe you will get 300S rivaling accuracy from it.

    Regards,
    Drew

  2. B.B.,

    Hope that your world has returned to a safer and more Texas-like weather and that you have weathered (sorry, pun alert) the recent polar vortex safely.

    I’m reading your blog reports with a different mindset. For the longest time I was viewing your reports with the mental question, “What is the best rifle.” Now I’m watching all of the variables that you control, or attempt to control, in the quest for precision. You adjust the sights to find bullseye accuracy as you working out the matter of precision. I’m going to have to review many of the reports of rifles that attracted my attention. I suspect that I was blind to your application of precision as you wrung-out this rifles.

    I live in the land of “good enough.” I will never take the time to get to the level of precision that you and others achieve. I’ve purchased a number of contenders for my “good enough” rifle. Most have disappointed. But as my father-in-law used to say, “A poor mechanic blames his tools.”

    Now I think that I shall sell off most of my small collection. I will retain a couple of the better spring power rifles and one PCP. I’m settling on .22 cal. Then I will shoot a lot of pellets. Practice, practice, practice…

    Dan

    • Dan,

      There is something to say for that particular philosophy. The fewer airguns you have and the more you shoot what you have, the better you become with those. Paraphrasing: Beware the man with one gun.

      If it were not for these old ladies that keep showing up at RRHFWA, I would only have three air rifles and one air pistol.

  3. BB

    I’m still new enough to air rifle target shooting that I need to ask what you mean by “follow through”. What constitutes “follow through” in target shooting?

    • Follow through is one of the key fundamentals of all shooting, not just target/paper shooting. Follow through is a key fundamental in most sports. Think about baseball, golf, bowling etc. and proper follow through in your motion is crucial.

      In shooting it’s about keeping your sights/reticle on target before, during and after the shot.

      • Kevin,

        Thanks for that comment. I think I’ve been holding sights / reticle steady on target during and after the shot, but I’ll be more attentive to it going forward.

    • Cstoehr,

      When pulling the trigger,… pull all the way through and hold it (instead of jerking it or giving it a quick pump or tap and let off.) That,.. and Kevin’s comment.

      Chris

        • Cstoehr,

          Trigger control is one of the other basic fundamentals to shooting accurately.

          Many folks a proponents of pulling the trigger until it “surprises you when it goes off”. You’ll see this “tip” in many books and hear it on the range when someone is trying to help a shooter with their fundamentals. I disagree with this advice.

          Your accuracy will improve if you get to intimately know when your trigger will release. You’re not surprised by it but know exactly when it will go off. It’s easier to get to know your trigger if you forget about shooting for ultimate accuracy and just have a shooting session that is focused on your trigger and when it releases. Once this happens you can introduce other fundamentals and further complicate your life.

        • cstoehr,

          Kevin has written about the trigger control method he prefers and I agree with his preferred technique when shooting from a very steady rested position. I think he is thinking rifle since that is the topic today.

          I subscribe to the alternative surprise Let-off when shooting Offhand rifle and pistol (unrested) because the wobble is so much greater.
          Okay! Now for the rifle details: when the sight picture is moving away from the Point Of Aim (POA) stop the trigger squeeze! When the natural wobble starts the sight picture motion toward the POA resume the trigger squeeze once again. The why: Your brain’s POA image is behind what is actually happening with the sight picture by more time that most of us believe. The Theory of this technique is that you will be closer to the POA when the Shot Cycle begins than if you try to anticipate Trigger Let-off and cause it when you THINK you are seeing the sight on the POA. Folks (coaches) have studied this technique and teach it to high level rifle shooters. There are various ways it is taught and will always be debated as to which works better

          Many Pistol Shooters think the technique that Kevin recommends is the way to go and some don’t: https://www.bullseyepistol.com/armymark.htm

          Clear as mud right!
          Think it through and it will make sense that pistols are different than rifles Off Hand. Just remember the trigger technique i recommend is for unrested rifle shooting which is always more wobbly than shooting from a; bench, bipod, sandbag, tripod rested position.

          As far as follow through we are all to quick to get off the shot to SEE the result. If we stay with the shot and take the time to predict the result without moving we all have the chance to become better Shots. Don’t just call the FLYERS call evey shot before you move it will help you feel the entire shot cycle and let you remember exactly where the sight picture was when the shot left the barrel!
          Scope, Reflex, Irons it doesn’t change the need to stay focused on the shot mentally just a bit longer/more than most shooters in fact do!

          shootski

  4. Here is the flip side of the coin:

    You can’t have too many if you are retired and have a convenient place to shoot at home. Each gun has to be accurate to a standard of your choosing. Shoot all of them and keep track of performance of each. There are so many variables. Look at the number of changes BB tried in today’s report!

    BB, this is one of my favorite kinds of reports. I’m betting on the Feinwerk but wouldn’t it be something if you discovered how to duplicate that claimed .06 inch group.

    Deck

  5. BB,

    Up until now, I had never compared the aluminum foil against the duct tape as a target backing.

    Curious to see which is better I ran a quick test comparing the two tapes on (typical) commercial heavy paper targets, commercial thin carboard targets and photocopier paper (because I print my own custom targets). I tested .177 caliber wad-cutter and domed pellets and shot samples through plain un-backed targets as a baseline. All shots had a fresh cardboard backer. Below is an image of my test for reference.

    In reviewing the results I come to these conclusions…
    – wad-cutters cut holes clean enough that you don’t need tape if you are using a cardboard backing to support the paper target.
    – domed pellet holes are much clearer when backing the target with tape.
    – thin carboard targets show the best holes (backed or not) and paper (thick and thin) benefits from backing.
    – both tapes work well, I think duct tape is slightly better for thick paper and foil for copier paper.

    Summing up, I only use backing tape when I am doing (serious) testing with domed pellets. Because I use photocopier paper targets I prefer the foil tape – mostly because I like that I can cut a bunch of pieces and “peel&stick” as required later.

    That was a fun exercise – hope that people find it helpful.

    Hank

  6. B.B.,

    Your article today prompted me to go open my shooting book and look at my notes for my long gone Beeman 400.

    I sent my Beeman 400 to Neil Johnson for a rebuild right after I bought it since the seals had disintegrated. It came back shooting to spec. Surprisingly the most accurate pellet out of many tested in my Beeman 400 was the lowly Meisterkugeln Rifle (8.2 gr).

    Since your Beeman 400 is shooting a little slow it might explain why the lighter pellets (around 7 gr) are doing best in your gun. I know you tried the Meisterkugeln Rifle pellets (8.2 gr) in part 3 of your accuracy testing but it might be worth trying the Meisterkugeln Pistol pellets (7 gr).

    • Kevin and BB,

      All of my 400/75s would agree with the Meister comments. For whatever reason, the Meisterkuglen pellets seem to shoot best that I bought back in the late 70’s to early 80’s. I still have about a dozen tins of them and they shoot just like always. I would agree to try a lighter Meister pellet for accuracy. Beeman Laser’s also shot well although I only have a tin or two of them left.

      My general observation is that your rifle may need to just break in more. You are doing everything right for best accuracy as best I can tell, so either the pellets are not matching well or the rifle has not settled yet.

      I am looking forward to your 400/300s shoot out. I bought some 300s rifles for the same purpose. I immediately found I can shoot a 400 better than a 300s as the 400 is just bigger and fits me better.

  7. Completely off topic: This question may have been covered earlier this year.

    Now that I have all the disclaimers out of the way, are there going to be any airgun shows this year? Malvern, AR? Findlay, OH? Columbus, OH? Texas?

    Motorman
    St. Louis, MO

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