Impact M3 Accuracy Question

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Zach

Member
Jul 18, 2022
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Mishawaka Indiana USA
I’m having accuracy issues with my M3. It’s a .22 with a 700 mm superior heavy barrel shooting NSA 27.5 grain slugs in .218 diameter at about 970 fps with an ES of 15fps. I’ve tried a number of different slugs and it seems to like these best.

My question is that I can get it tuned in so that at 40 yards I can shoot 5 shots that I can cover with my thumb nail. I then go to 65 yards and can get it to do about the same for a group or two. After that the groups open up at random and it tends to spray them around. Often times if I keep shooting it will get better for awhile and then worse again. I’ve shot some pellets with the regular liner with a little of the same problem only usually not as extreme. I’ve tried shooting at 100 yards with slugs and pellets and sometimes I can get three shots touching but the next two or three will be an 1” or 2” off any given direction at random.

My question is does the gun have an issue or is something else going on? I’ve tried cleaning the barrel and it’s the same thing. What I consider great accuracy for a few groups and then it falls apart again. Any help or advice would be appreciated.
 
The thing I've found as far as slug accuracy is once you find the size and speed your barrel likes, it's the fit of the slug into the breech that makes for consistent accuracy, discrepancies in weight for slugs out of same box, not as much. Remember, a slugs accuracy is dependent on spin and speed in tandem not just one or the other. Measure some out and see how each different sizes group, that's why you get some good groups and some bad with slugs str8 out of the box.....some.barrels are less fussy than others. Sounds like you are close to having consistent great groups! I shoot NSA from my RAW and when I feel a slug load too easily into the breech, I know it usually will not shoot as accurately as a snug loaded slug. So, get out the calipers....LOL!
 
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Zach said:
I’m having accuracy issues with my M3. It’s a .22 with a 700 mm superior heavy barrel shooting NSA 27.5 grain slugs in .218 diameter at about 970 fps with an ES of 15fps. I’ve tried a number of different slugs and it seems to like these best.

My question is that I can get it tuned in so that at 40 yards I can shoot 5 shots that I can cover with my thumb nail. I then go to 65 yards and can get it to do about the same for a group or two. After that the groups open up at random and it tends to spray them around. Often times if I keep shooting it will get better for awhile and then worse again. I’ve shot some pellets with the regular liner with a little of the same problem only usually not as extreme. I’ve tried shooting at 100 yards with slugs and pellets and sometimes I can get three shots touching but the next two or three will be an 1” or 2” off any given direction at random.

My question is does the gun have an issue or is something else going on? I’ve tried cleaning the barrel and it’s the same thing. What I consider great accuracy for a few groups and then it falls apart again. Any help or advice would be appreciated.
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Well, I hate to say it, but first we have to eliminate the shooter as the cause of the problem. Most people have difficulty shooting multiple consistent MOA groups at 100 yards with ANY gun (Airgun or Firearm), and shooter fatigue and inattention is a very real issue.

Basically what I read into what you wrote is that at 40 yards you get consistent groups of thumbnail size or approx 1 MOA And that out beyond 60 yards these become more difficult. I can tell you that just that statement alone is probably true of everyone and every air gun.

As outlined by you, your accuracy sounds decent, maybe even quite good (forget the nonsense that you see from people who claim that they always shoot one ragged hole at 50 yards, every day and every time, and time after time. It’s just not true.)

So, first see if other, competent, shooters have the same issue, in the same way (because everyone will suffer to some extent). If other people shoot the gun well, then maybe it is you and you need to work on your technique, or perhaps, just take a break after shooting a couple of groups then start again.

Only after you’ve eliminated the shooter variable is it really worth going down the rabbit hole of even better, and more consistent, accuracy. Now you’ve started on a a never ending journey. You first need to chronograph your gun and ensure that you are getting consistent speeds, since dramatic changes in speed can lead to fliers etc. Generally we’re talking about +/- 20 FPS though. Frankly I wouldn’t sweat anything under about 2% of your average.

You will also need to see if the issue is inconsistent ammo. Good luck with that as it has its own rabbit hole, and may end up with you washing, lubing, weighing, measuring diameters, and then sorting by these parameters, of all your pellets and slugs!

You may also consider (after the Chrono work and possibly the ammo stuff) using a Carbon Fiber liner sleeve, epoxied or not, as well as a harmonic tuner, barrel stiffener and barrel support, AirMarksman backbone/rail to reduce flex, etc., etc…

Then again, your accuracy doesn’t sound that bad. Maybe just practice a bit more and take some breaks to smell the roses along the way.
 
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Oh I’m more than willing to believe at least part of it is me. I’m not after one hole groups really. I shoot pest birds starlings and sparrows mostly. My thing is that it seems to go from being able to hit a sparrow consistently at 40 yards to not being able to hit them at all in a couple shots. There’re times while I’m target practicing I can see POI literally jump an 1” or more.
 
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Try just shooting at 90 yards untill your groups are acceptable. Then shooting at 30 hards will be easy cake.

Remember that if you could see the center of earth rotating at the size of a wrist watch you would see that is moves at half the speed of the hours clck hand (a full round in 24 hours). But of you see it at the Ecuador it rotates at 1,375 kms/hr.

A tight group at 40 yards is a wide group at 100 yards and a super wide group at 300.

That one is the must common error in sighting powder burners. Many people think that if they sight the rifle at 33 yards, the rifle will be sight at 150 or 200..... That is false. You can make a first try at 33, but you need to make the fine tunning at the distance you want your rifle to be zeroed 200 or 300 yards.
 
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Zach said:
Oh I’m more than willing to believe at least part of it is me. I’m not after one hole groups really. I shoot pest birds starlings and sparrows mostly. My thing is that it seems to go from being able to hit a sparrow consistently at 40 yards to not being able to hit them at all in a couple shots. There’re times while I’m target practicing I can see POI literally jump an 1” or more.
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Depending on the wind, at your position, and at the target. 40 yard sparrows are quite “missable“🤓 Do like the FT shooters do and hang a wind indicator off your muzzle…
 
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As many have mentioned there are a lot of variables for why shots may be on and then off. It could be:

Shooter

Scope mounting issues like screws not torqued properly or loose.

Internal scope issues like tracking issues

Slugs being slightly off in dimensions from the previous

Something loose on the mounting rail/frame of the gun

Regulator inconsistency

Dwell time of the valve

Seating depth inconsistencies

Oring inside breach/barrel issue

Stiction on the valve rod

Etc....

It is basically endless and can be frustrating to find at times. It looks like you are close. One question I pondef is do you have to readjust your scope everytime or does it fall back in line on its own?
 
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I really appreciate all information from everyone. I talked to Utah Airguns yesterday and the tech I talked to was very helpful. He told me some tuning numbers and I was really close. I had my valve at line 4 which is the last line but he told me that I could go the equivalent of 6 lines. (I wasn’t sure if I could do that safely) I opened it slowly until about line 5 or so and I suddenly seemed to get better groups and consistency than I’ve been able to for a long time at least out to 65 yards. I ran out of time and daylight so I’ll see if it’s still there this evening if I get time.
 
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Bigragu said:
Also- are you allowing the plenum to fully recharge?

I was a victim of the “count to 12 before the next shot” thing for s long time, and that all went away when I switched out the reg piston to the new brass one. The 720 plenum fills fast
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Where does one get this "new brass" reg piston? Are you switching out just the piston or the whole reg assembly as well?
 
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