This report covers:
- Accuracy
- Workaround?
- Ring height versus zero?
- What to do
- Rant over
- Scope ring height
- Clearance
- What does scope height affect?
- Summary
Today we’re going to get into scope rings pretty deep. And right off the bat I have the subject for you. The report on scoping the Gamo Arrow brought up some interesting things that we need to consider before we begin. The first is accuracy.
Accuracy
Putting the pellets in one hole is the definition of accuracy. Where those pellets land is a different issue that we are considering in this report.
The Gamo Arrow that I scoped was shooting too low. It was putting them all into the same hole but the hole was in the wrong place. What needs to be done now is to adjust that scope to hit the target at which I aim — to hit the aim point (or close to it, so the aim point isn’t destroyed, making me guess where it was). The Gamo Arrow rifle is already accurate, because it shoots all its pellets to the same place.
Workaround?
When I said “workaround” in that report I wasn’t talking what you do about scopes that can’t be zeroed. I was referring to the things I do so I can complete a test. Rain or shine, everyone expects a new report on this blog every working day of the week. So I often don’t waste my time trying to do all things right. I WORK AROUND the problem, if I encounter one, knowing that the next time I test that rifle there is an issue to be resolved.
Ring height versus zero?
Does the height of the scope rings determine the zero of the scope? NO! NO! NO! Ring height has very little to do with the scope’s zero. Low rings are not what are needed when a scope shoots too low. A downward angle on the scope is what we need. And we can get that regardless of the ring height.
And here is a comment to that report that I have to address.
“I sincerely think, and I hope Gamo read BBs great posts and our comments. If they can get these [barrel droop] issues solved, they truly have a great beginner rifle at hand which will probably also be bought by more seasoned shooters.”
Resolve the barrel droop issue? If Gamo ever could do that they would be the first company to do so. Winchester, Mauser, Weihrauch, BSA, Remington and all the AR-15 makers haven’t resolved it. Perhaps Whiscombe made air rifles without droop and I may have seen a couple TX200s that didn’t droop, but darn few other makers of firearms or airguns make rifles that don’t droop.
What to do
The thing for you to do, instead of looking for that unicorn air rifle that doesn’t droop, is to plan what you will do when you discover how much droop your air rifle has. Or, you can just show up at the range and let BB Pelletier fix it for you, as I already have done many times. Guys — THIS is why I always shim the lower ring saddle under the rear scope tube.
I have been trying to get this point across in this series. Please reread the following text from Part 2:
… nearly all firearm rifles shoot low! Yes, they do. And, because of that, they need scope mounts (rings) that have some rear elevation to get them up on target. When gunsmiths were mounting scope rings by hand they were taking care of this in the job they did. They lapped the rings after mounting them so they put the scope on target at a specified distance that was usually 100 yards.
The worst firearms with a down angle are the AR-15 platforms that actually have scope rings that produce X number of minutes of down angle. They sell them for long-range shooting, but most ARs need them to keep the scope in adjustment at 100 yards. Without them the scope either has to be shimmed in the rear or it gets adjusted so high that the erector tube return spring relaxes too much and the scope won’t hold zero. Shooters blame the scope when it’s the rings that are at fault. I will say that premium scopes can be adjusted higher than cheaper scopes, so the cheap scopes get the rap for not doing the job when all along it’s the rings.
Rant over
BB doesn’t get on his soapbox very often, but this subject is one that puts him there. When I worked at AirForce I took all the technical calls, and the two questions that were the most common were, 1. Why can’t I pressurize my AirForce Condor air rifle tank to 3,000 psi and get decent velocity? and 2. I have tried three scopes on your rifle (at this point the rifle was always OUR rifle) and it still won’t shoot a group.
For question number one after a half hour conversation they either understood that their power curve happened between two numbers that did not start at 3,000 psi or else they sent the rifle back. The funny thing is, if their power curve came on at 2,700 psi on their Condor and gave them the 20 powerful shots that we advertised (.22 caliber Crosman Premier pellets going out at over 1,200 f.p.s.) some people were still not satisfied. In essence they said, “I paid a lot of money for a powerful air rifle that gets pressurized to 3,000 psi and this one doesn’t! I want my money back!” That’s like getting angry because your speedometer says you are going 100 kilometers per hour when you know darn good and well you aren’t going any faster than 62 miles per hour. Look it up.
By the way, Americans, when you travel to Germany next year be sure to visit the city of Ausfahrt. It’s huge! You’ll find exits to it off the Autobahns all around the country.
For question number two, if the customers followed my instructions and dialed their scope’s elevation down 60-80 clicks, their rifles suddenly became “accurate.” The problem then was how to get those tight groups back up to their aim point. That problem took two half-hour conversations at different times, because they first had to do the scope adjustment thing that I told them (and you) about just now. Then they had to call me back after discovering that their rifle was accurate so I could tell them how to adjust their impact point up to hit the aim point. Either that or I was as dumb as a bag of hammers and they returned the rifle.
Scope ring height
What, then, does the height of the scope rings height affect? Why are there scope rings of different heights? Let’s start with the big one — clearance
Clearance
Before airguns were scoped there was a clearance problem with firearm rifles. The most common problem was the bolt handle came up so far that the scope prevented it from opening all the way. Anyone who has ever scoped a Russian Mosin Nagant rifle knows what I’m talking about. Their bolts open with a 90 degree turn to the left. That puts the bolt handle straight up.
When the Mosin Nagant bolt is opened (it’s closed in this picture) the handle comes straight up. If you don’t modify the handle , the scope has to be mounted ahead of the bolt for clearance. This is a UTG scout scope with an extra-long eye relief for exactly this problem.
The problem with mounting a scope high is your head then has to get high enough to see through it.
See how high my head has to be to see through that scope?
The Russians did not design the Mosin to be scoped. They designed it to accommodate the many different ethnic groups found in the Russian Army. One consequence of that is the buttstock drops more than any western military rifle. That exacerbates the high scope problem.
The Soviets solved the bolt issue for their sniper rifles by lowering the bolt handle. That allowed the scope to be mounted farther back and closer to the shooter’s eye.
This Hungarian Mosin sniper rifle has the lowered bolt handle so the 3.5-power sniper scope can be set back above the receiver.
Air rifles can have clearance issues as well. Many rifles that use a rotary magazine have the magazine sticking up above the top of the receiver. It has to be cleared by the scope and that often means using high rings.
This Air Arms S510 illustrates the problem of scoping a repeater very well. The scope has to clear the rotary magazine that can be seen sticking up above the flat receiver. The dimensions of this scope put its turret exactly over the magazine. This forces two things — high scope rings and two-piece scope rings.
So clearance is one big reason for high rings. Another reason is also a clearance issue, but it’s clearance for the shooter rather than for the scope. AirForce airguns illustrate this very well.
The straight line of the air tank on an AirForce air rifle that is also the rifle’s butt pushes the shooter’s face up high. Also, your sighting eye has to get around the round air tank in order to align with a scope that is centered on the rifle’s frame. A flat buttstock makes this easier.
I used to demonstrate to dealers at the SHOT Show how to hold AirForce rifles to handle the scope height issue. It takes a modified hold with the bottom tip of the buttplate in the top pocket of the shoulder, and once you have it, the rifle is as stable as any rifle ever is. Since there is little to no recoil, this isn’t a problem.
BB fatface sights an AirForce TexanSS. There is no scope mounted but look how high my sighting eye has gone. The scope has to be up there to meet me, and that means high mounts. And by the way, this picture illustrates why I bought a Labradar chronograph — so I don’t shoot it!
What does scope height affect?
A high-mounted scope is just as precise at all distances as one that’s mounted low. However, if you cant (tilt) the rifle at all, the high-mounted scope will be affected more than one that’s mounted lower. That is the major advantage of a low-mounted scope. You can read about this in my blog report called What cant does.
You can also fit a scoped rifle that has a low mount into a rifle carrying case easier. That’s a minor concern, but a very real one.
Summary
I hadn’t initially planned on going into so much detail about ring height today, but as I wrote the subject just kept expanding. I decided to just run with it to the end instead of condensing things. I hope I have written it in a way that’s easy to understand.
B.B.
Scope rings lead right into cheek weld and line of sight. Glad you are calling attention to it. I see to many fellows smashing their cheek again the butt stock just to see through their scope. Next up will be length of pull?
One thing seem certain, we should all get drooper mounts!
-Y
Yogi,
Drooper mounts or adjustable rings. I have both. They come in real handy.
BB
When I was in Germany, I don’t know how many times that to get somewhere, I had to start a trip by going towards Eingang!
Is there a possibility of putting a ‘kink’ in the scope tube by having the rear mounting ring higher than the front ring? (thereby putting the scope tube on the ‘edges’ of the rings)
Thanks for having a blog that makes me consider things that are right in front of me, but I might not notice.
Bill
billj,
Indeed there is. Tightening the rings too much can cause such. Adjustable rings are expensive, but oh so nice.
“…THIS is why I always shim the lower ring saddle under the rear scope tube.”
B.B.,
I’m with you all the way; I HAVE paid attention to your reports, and that is why ALL my scopes have a shim under the rear scope tube…and it has worked out well…just as you said it would; thank you. 😉
Blessings to you,
dave
I have seen examples of guns that adjust to the scope whereby it’s typically the butt shape that can be altered. I wonder what efforts, if any, have been made to create a scope that adjusts to the gun?
Surely a scope doesn’t need to be mounted above the barrel. But if that were desired, then how about a porro prism style scope?
3hi,
There are such things. I have seen them.
I have also seen mounts that place the scope off to the side. The issue with such is that the further the ocular lens is from the barrel, the more error at various ranges are introduced. Look at it as with fighter planes that have machine guns in the wings. They are adjusted to have converging fire at a certain range.
A very high scope becomes a real issue when shooting at random short range distances.
Put a few targets at distances from 3 to 30 feet. Use a pellet rifle with high mounted scope, and another one with iron sights. See which one works better.
BB-
Errata-
Section- Accuracy- ‘Putting the pellets in one hole is the definition of accuracy.’
A group of pellets in one hole is the definition of precision. Aligning that group, or any size group, on target is the definition of accuracy.
To illustrate-Which would you prefer when shooting at a 1” diameter target?
A 1/2” group (precise), but it is centered 2”left of the target.
A 1” group that is centered (accurate) on the target.
I will willingly give up some precision in exchange for greater accuracy.
I looked up Auspahrt. Funny,….very funny. Oh, by the way, this is a much needed series for a first timer as well as a geeser like me.
rk
I am, as I age, becoming more familiar with the city of Branefarht.
Ed
BB
Is there really a cost advantage for rifle makers to intentionally manufacture droopers?
If not, they must all have eternal patents on all drooper mounts and adjustable rings.
Seriously I also shim the bottom (sometimes the right side for horizontal) of rear rings of most scopes. In addition I probably own more drooper mounts and adjustable rings than rifles to put them on. The reason is to be able to get maximum tension on that turret spring.
Deck
Deck,
It’s not intentional, but It does happen. I guess if they were all elevated too much that would be a different problem.
BB
Decksniper,
On air rifles most “droopers” are break barrels and that was not a problem until folks mounted scopes on the Reciever; as long as the sight system (front and rear if two of parts) are/is mounted on the barrel, shroud or handguard there is NO droop.
Typically it is caused by fat breech seals and the lock up latch. IF manufacturers built no droop into their barrels for scope mounting they would have many more returned rifles and a far more expensive fix.
On AR-15 “droopers” that B.B. is hot under the collar about it is typically the gas block and tube that cause the problem of depressed elevation.
shootski
BB,
Do you ever “dial-down” the scope elevation to setup a long range rifle? …I shoot a reference group at 25-30 yards, dial the scopes’ elevation down ( gently, to the physical minimum then up a turn or two to give me some low end adjustment) and then align the cross hairs to the reference group using the vertical adjustment in the (FX No-Limit) scope rings. This approach gives me the maximum elevation adjustment before I lose spring pressure on the erector tube.
Talking about accuracy, I thought I’d share one of those “lucky groups” I shot. When I get on a roll and start stacking pellets I try to see how long I can maintain the group until I blow it. Last night I was fine tuning my Impact and managed a 13 shot string to shoot a sub 1/4 inch group at 40 yards before I ran out of pellets, needed to refill the tank and had to go in for supper. Took that as a sign to leave well enough alone before I spoiled it. LOL! I was . 22 JSB Monster Redesigns at 950 fps.
Nice group, made me smile – but I won’t “belive it” until I can shoot five of them consecutively. 🙂
Hank
Hank
That is a truly impressive string of shots. Is this Impact modified in any way?
Ed
Ed,
I’m setting the Impact (MK2) for experimenting with slugs so I’ve changed to a “slug liner” (different twist rate than a pellet liner) installed a carbon fiber stiffer tube and increased the power a little bit.
The Impact was also shooting excellent groups with 18gr JSBs at 890 fps before I reconfigured it for slugs.
Once I’ve satisfied my curiosity on slugs I’ll be changing the Impact back to the 18s, they are much less expensive and I don’t need 50 + fpe LOL!
Hank
Thanks Hank. I was curious as to whether any stock guns other than the stuff they shoot at the olympics could produce that kind of precision. I know that those shooting at that level do tend to make an effort to improve their equipment,, but Anshutz or FWB both tend to “shoot in” by themselves without tinkering. I guess I should have known, as I HAVE read your comments before.
Ed
Hank,
Fantastic group, congrats. The ,22 JSB Redesigned pellets are by far the best long distance pellets I have tried in my RAW rifle.
Great report on barrel indexing. I was out of town just catching up on the blog. Both you and the gun were able to show the process very well. Most of my guns and myself would have too much scatter on the target to see the pattern.
Don
Thanks Don! …Wish I could shoot groups like that all the time 🙂
Glad you liked the indexing blog, I always have to wonder if there is enough interest in that kinda subject.
Hank
Vana2,
First things first! NICE GROUP!
Those paper hole reinforcers need to do a better job of keeping those pellets IN THE HOLE for you!
I have used the FX No Limit rings along with some others that adjust for the vertical. I have gone so far as to replace the Weaver Mounts on both my DAQ .58 caliber pistol/carbine and Short rifle with PICATINNY 25 and 30 MOA (about 7.3 and 8.8 MILRAD) rails. I shoot the Big Bores with an optically centered scope (I use the mirror method to overlay the crosshairs) then shoot a Tall Target at my near and far estimated zero points. That Tall Target gives me the approximate MOA/MILRAD value needed for the PICATINNY rail and also confirms the receiver/barrel/scope alignment.
None of that should be done until you have TOTALLY broken in and wrung out the DOPE on the platform as well as settled on your choice(s) of ammo. I have a Gunsmith that I trust do the drilling and tapping for larger screws for the PICATINNY rails. He was hesitant when I first asked him to do the work since he thought the DAQs were built like “regular” airguns without enough metal to work with.
As you know and folks really need to learn if they want to shoot beyond typical airgun distances not being close to optical center makes sub moa shooting almost impossible.
Shimming certainly works for B.B.’s needs but I would NOT like having a shim fall out and get lost while i’m many miles (kilometers) from my home, Skished, vehicle, or base camp,
shootski
.
“… managed a 13 shot string to shoot a sub 1/4 inch group at 40 yards before I ran out of pellets,”
Nice shootin’ there, Hank! 🙂
Off subject, a old time looker is back on PA! A Diana bb rifle (Yes Rifle). It has a rifled barrel?? Hmm. Lead bb’s maybe? Maybe BB will get his hands on one for us.
/product/diana-oktoberfest-bb-rifle?m=5710#11527
Doc
Doc,
Tomorrow.
BB
B.B.
Oh SWEET! Looking forward to it!!!
Doc
“Ausfahrt? Can you get from there to Barcelona?”
Hahahaha! 🙂
Manuel,
No, but you can have a hammer sandwich.
BB
I love shooting targets with my TX200. A month or so ago I noticed pronounced tearing of my targets. The targets are set at 25 yards. Hummm . . . my pellets are entering the targets sideways. I’ve been shooting Air Arms Diablos, 16 gr. My groups are consistent. OK, next I purchased a chronograph (as you so recommend, BB). My TX200 is shooting at 640 fps. I’d expect this of my CO2 rifles, but of my TX? I need some help here guys. What am I doing wrong here? It’s just got to be me; my two and a half year old TX200 can’t be at fault, it’s me, right?
Hoppalong Doc
/blog/2021/12/tx200-mark-iii-part-1-2/
A good place to start.
shootski
Shootski: I truly appreciate your input. I have BB’s entire series on the TX200 on my bookmarks. My rifle Is a 22cal and from what I’m able to discern, it should be shooting in the neighborhood of 750 fps.. Due to it’s relative young age, I haven’t torn into it yet. I’ve used a few drops of Pellgun Oil on the appropriate moving parts and keep it shined with Balistrol following each day’s play (but then, I treat all of my guns in this manner). I have trouble imagining my TX needing a tune at this early stage of it’s life, but what?
How many shots do you have through it (approximately)? Did you buy it new? Would it be due for a drop or two of chamber oil then check velocity?
I’m sort of surprised that it is still shooting to point of aim when the velocity is so far off that pellets are not flying straight. Also, with diabolo pellets, it is surprising that they aren’t flying nose first at the end of a 25 yard flight just based on their shape. Does your gun have a moderator on it? Could there be anything obstructing the pellets’ exit from the muzzle?
Sorry, more questions than answes from me, but I am relatively new around here. Hope my questions lead you to the answer.
I appreciate your reply . . . I am really anxious to get to the bottom of this. I purchased the rifle new through Pyramyd in the Spring of 2020. Judging from the number of empty .22 cal tins, there have been somewhere between 4 & 5 thousand pellets shot through the barrel of my rifle. The gun is completely stock. Earlier this year I lubricated the seal with just a couple drops of silicone chamber oil. The rifle shoots quite smoothly, with just a barely noticeable “twang”. There is also a barely noticeable amount of “dieseling”, just as there has been since new. The tearing of the targets has only been noticeable to me in recent weeks. I really appreciate you guys helping me diagnose my favorite guns’ illness. At this point, my Dragonfly seems to have as much power as my TX. Thanks again, Orv.
Orv,
Check the breech seal. It’s out of sight and easy to overlook.
BB
Thank you. I’ll get on it tomorrow. Orv.
I was out at the range this afternoon and my chronograph averaged 617 fps on a 10 shot stri g. This is only getting worse. I’ll definitely be checking my breech seal tomorrow. Thanks again, Orv.
I suppose that I’m embarrassed here, but I don’t really know how to get to my breech seals. I don’t feel qualified to disassemble this rifle, and am concerned about voiding my warranty if I did. Tom, I find where you clearly demonstrate taking this rifle apart, but is this absolutely warranted? I’m not afraid of spending money here, but throwing good money after bad is foolish in my eyes. I’ll fix this problem myself if I can . . . but hey, I’m rambling here when all I need is the go light in the right direction. Please help, Orv.
Hoppalong Doc,
/product/air-arms-barrel-seals-fits-tx200-pro-sport-air-rifles?a=4078
I don’t own a TX 200 but this should not take any disassembly to instal them Orv.
I could be totally wrong but it would seem you can open the loading port and get to both of them.
/model-schematic/m/air-arms-tx200-mkiii-air-rifle/174#4078
shootski
PS: read the reviews to see how this pair of barrel O-Rings will in all probability fix your air rifle.
My first scoped Deer rifle was a M-1 Garand that I used a B-Square side mount on, it utilized the rear sight mount for installation. No “bubba” type harm came to it. I decided to not have it converging at a certain distance but knowing how far to the right it shot. If memory swerves it shot 2″ to the right and I lived with that. These days if given the option I install 20 MOA Picatinny rails as a rule..