Vepr accuracy degradation, seemingly from bore fouling

[MeatAxe556]

Although most of my AKs have consistent decent to mediocre accuracy, at least they are consistent no matter how many rounds I shoot through them between cleanings.

My 16" bbl. 7.62x39 Vepr is different: with a clean bore I have no problem putting 3 rounds in a 1/2" or less group with Hornady SST at 50 yards (using a scope). However, I'm noticing the accuracy degrade rapidly after 20 rounds or so to @ 3" groups or worse. This barrel probably has 500 to 1,000 rounds through it. However, this accuracy degradation after the bore is cleaned and relatively few rounds are fired is a consistent problem.

Anybody else have that happen?

I'm using Patch Out brushless bore cleaner, which has done a great job cleaning my other rifles, as it chemically removes powder, carbon & copper overnight without scrubbing the bore with wire brushes. Most of the fouling coming out of the barrel is powder residue.

Any suggestions?

Thanks!

 

[PiggiePluggin]

Leave the copper and only clean carbon when you plan on letting it sit for a long time.

 

[BCP]

Say it starts shooting 3" after a 20 shot string, you set it down for awhile and try again - what do you get?

 

[MeatAxe556]

Say it starts shooting 3" after a 20 shot string, you set it down for awhile and try again - what do you get?

After the first 20 or so shots, accuracy stays at 3"+ groups @ 50 yards whether it sits for 20 minutes or several weeks.

Veprs have among the thickest AK barrels available (chrome lined), and for stamped AKs have among the stoutest (RPK type) receivers, so I don't think it's a temperature issue. They're built to shoot and shoot and shoot and shoot (full auto) without much in the way of maintenance.

What's puzzling to me is how it can have some pretty decent accuracy after the bore has been cleaned and then fall off to poor / mediocre accuracy after relatively few shots and stay that way.

I'm wondering if it might have some burr in the bore that's accumulating fouling...very strange. I know AKs aren't tack-drivers, but every one I've shot is at least consistent.

 

[BCP]

For starters I would quit throwing dollars downrange in the form of hornady SSTs. I'd blast away with wolf steel case and iron sights. Second of all check the crown and if it has a muzzle device make sure that the bullets aren't hitting it on the way out. Thirdly you could try bore scoping it but honestly....it's an AK. They are bullet hoses. My zastava PAP is the most accurate X39 AK I've ever shot and it's still about 3MOA.

 

[PiggiePluggin]

Use Google to look up why cleaning copper out of your barrel is bad. I agree, it's an ak and not a precision rifle, but if you are trying to get the most out of it accuracy wise, leave the copper in the barrel. Shoot a hundred rounds or so and see if it tightens up.

 

[MeatAxe556]

For starters I would quit throwing dollars downrange in the form of hornady SSTs. I'd blast away with wolf steel case and iron sights. Second of all check the crown and if it has a muzzle device make sure that the bullets aren't hitting it on the way out. Thirdly you could try bore scoping it but honestly....it's an AK. They are bullet hoses. My zastava PAP is the most accurate X39 AK I've ever shot and it's still about 3MOA.

Oh yeah, the SST is just my "go to" ammo for hunting and SD and it does achieve @ 1 MOA with SST for the first several rounds.

I shoot just about every brand of 7.62x39 from surplus on up. I did several 30 round mag dumps with Tula/Wolf/GT to test some new surplus mags and to test the integrity of the bullet guide I installed. No failures to fire at all, just the aggravating loss of accuracy after relatively few rounds. It's the same with a muzzle brake (Bulgarian 2 slot - no bullet strikes) or without. The muzzle crown "appears" to be fine.

 

[MeatAxe556]

Use Google to look up why cleaning copper out of your barrel is bad. I agree, it's an ak and not a precision rifle, but if you are trying to get the most out of it accuracy wise, leave the copper in the barrel. Shoot a hundred rounds or so and see if it tightens up.

Thanks, I will give that a try. Does it matter that it's a chrome-lined bore?

Patch Out does a good job of taking everything out of the bore. Will try some Carb Out and see if that changes anything, as nasty as that stuff is to handle.

 

[PiggiePluggin]

Just get some of the mpro 7 carb cleaner with a jag and cotton patch. I don't use very abrasive stuff in my barrel everyday unless I plan on stripping the copper out every 1k rounds or so. Copper is just going to keep the consistentcy in the groups till it starts to spill out the front of the barrel. There are a lot of top shooters that condone not cleaning your barrel till accuracy starts to drop off again. I stay away from very abrasive stuff with ammonium in it. Mixing chemicals and possibly etching the barrel. In all honesty, most people wear barrels out quicker cleaning them than actually shooting them. Carbon isn't necessarily bad, it's just about finding that balance of good dirty and bad dirty and learning the gun. Literally knowing that (for example) at 500 rounds your zero starts to diminish and is time for a full bore clean. I know that my cold bore shot under 300 rounds of fouling will impact 0.25 high without fail. If you plan on letting it sit till next deer season, sure clean it. But a month of carbon isn't going to do anything, especially a chrome lined one. Copper will actually help preserve the life, by not allowing the rifling to wear away as quick. There are so many variables in this situation. Are you shooting with the scope maxed out? I try and group with my bushnell hdmr on about 8/21 power @ 100yds. Just enough to see the dot in the target. If I see the holes in my target, I start to get what archers like to call "target panic." I stress out and my groups start to get larger and often times I start to blame my gun. My suggestion would be rent a led sled from the range or borrow one from a buddy. If you can't do that, take the time to build your shooting position. Allow yourself the time to set up the sand bags and rear bag if you use one. Get the scope lined up and close your eyes for like 5 seconds. Open them and If the scope moved, that's on you. Line it up and practice closing your eyes and opening them ensuring the gun doesn't move from just sitting. If you want, back it out to 100 yds so you can't see the rounds impact the paper causing you to rush things. Are you shooting through scope barrel mirage? Look up pics of surpressors with shrouds over them and see why. There are so many factors that blaming the gun should be the last thing. How are your scope rings? Are they tight? Are you shooting from the prone unsupported? I'm not bashing you, just all things you need to look at. Consistent groups come from consistent shooters.

That's a pic of a freshly copper/carbon stripped barrel with roughly 8k rounds, below is a pic of the same barrel untouched about 100 rounds later. That went from a 1.25 group to a 1/2 moa group out of a gas gun which is bolt gun accuracy status.

Take pics of your groups for documentation if you are that worried about it. If you are concerned with groups and shooting sub to 1.50 moa groups, you are going to need to adjust your set up for doing so. For example, cheek weld the same every time, can you adjust for paralax in the scope? If not, rushing the shot to try and "get a better group" and not realizing your cheek to stock weld was different than the last group it could yield a 3 moa group.

For example, Top hole is cold/dirty bore. I now know I need to move it 0.1 mil down to get the most out of my cold/hot bore groups.

 

[MeatAxe556]

^ Thank you!

All good advice!

I do use a lead sled, so I can try to minimize my error input.

 

[MeatAxe556]

^ Thank you!

All good advice!

I do use a lead sled, so I can try to minimize my error input.

Also wondering if using some J B Bore Compound (on a chrome-lined bore) or similar would help smooth out the bore and and make it less susceptible to fouling so it groups more consistently?

Thanks!

 

[MeatAxe556]

Took the Vepr out shooting this weekend, using Hornady SST. After a thorough cleaning with Patch Out and Carb Out and a couple of fouling shots, I was getting good half-inch or less groups at 50 yards. I was giving the bore plenty of time to cool between 3 shot groups.

Then, sure enough, the groups started spreading after 15-20 shots. Cleaned the bore with Carb Out, which came out very dirty (carbon / powder fouling), especially considering this is high-end US ammo.

After I cleaned with Carb Out, the Vepr was shooting 1/2" groups again, only to open up again after 15 or so shots.

At this point, I'm guessing the bore is rough, which accounts for the excessive fouling leading to degraded accuracy. Will try some JB Bore Compound and see if that smooth things out.

Any other suggestions?

 

[dmike]

Any other suggestions?

Piggiepluggin suggested resisting the urge to clean for100 rds, you don't want to try that?

People talk about copper equilibrium and how copper acummulates on a clean barrel, it's dynamic so the properties can change with more shots. What's the most consecutive shots you've fired without cleaning, is it possible that the groups come back in at some point? Not dismissing the burr idea

 

[MeatAxe556]

Piggiepluggin suggested resisting the urge to clean for100 rds, you don't want to try that?

People talk about copper equilibrium and how copper acummulates on a clean barrel, it's dynamic so the properties can change with more shots. What's the most consecutive shots you've fired without cleaning, is it possible that the groups come back in at some point? Not dismissing the burr idea

I've probably fired at least 200-300 rounds between cleanings and the accuracy has never come back to the @ 1 moa it has when the bore is clean. Accuracy just gets worse and worse as the round count piles up, to the point that it doesn't really group., bullets are all over the place even with a scope.

Being an AK, I don't expect it to be a tack driver, but it should at least be consistent "minute of man." My other AKs are at least consistent, anywhere from @ 1 moa to 3-4 consistently.

 

[PiggiePluggin]

Are you shooting 2-300 rounds per range day? If so, fire 15 rounds, see what it's grouping like. Put the gun away. Go home and leave it alone. Go another day and shoot another 15, see what it's doing. I'd be very surprised if a barrel with over 300 rounds still has burrs. I'm more inclined to say it's shooter fatigue or something along those lines. I've also gone months and countless rounds before cleaning to see a noticeable change or degradation in accuracy.

You mention it being a scoped ak...how is the scope mounted? I know they are completely different guns but I see people running into the same issues when dealing with cheap mosin mounts.

I also don't think a rough bore is going to account for excessive carbon or copper fouling. It's my understanding that when you do a barrel break in (take jp for example) you shoot 20 rounds, clean, another 20, clean till about 60 rounds, then again at 300. The reason for cleaning is to remove the copper to allow the rounds to actually smooth out the burrs. Think about it...a patch with jb vs a bullet? Bullet wins in knocking down burrs. I think you've cleaned it enough to safely say you have made bare bullet to bore contact to get rid of burrs.

Excessive carbon fouling is usually caused by an untuned gun, suppressor or crappy rounds. Do you have a gas reg? Are you putting lube down the barrel?

My suggestion would be, see if cleaning the rifle is giving you a false sense of equipment satisfaction/confidence. After you shoot 15 rounds, are you looking for the rifle to fail? Can you shoot out to 100 yds so you can't see the rounds impact? Seriously, 15 rounds isn't even a full mag unless you live somewhere like N.Y.

Also, you don't leave jb in the barrel when you shoot. You are supposed to get it all out. If you are leaving anything inside the bore when shooting besides what the bullet leaves behind, you are creating problems with pressure, the friction of the rounds etc, not to mention when you fire, the stuff you leave in the bore turns to carbon meaning the heavy fouling you are talking about.

 

[dmike]

+1 for scope mount, what are you using? I've got a MI on my vepr 54r and I have to really crank it. Are you removing/replacing it on every trip? If so maybe it's shaking loose after your first few shots?

You could also try a 10 shot group after cleaning instead of 5x3s. For me 3 shot groups can be misleading. A 10 shot group after cleaning and another 100 rds later would be interesting

 

[MeatAxe556]

I'm using a Midwest Industries mount and quality rings and either a compact Leupold or a Nikon scope, all tightened down well.

When I first started shooting this Vepr and getting these inconsistent results, I thought it was the Leupold scope, so I sent it back to Leupold for service. They sent it back saying it was all OK. I also use this same exact equipment on a .308 Vepr, which is consistently (if not pinpoint) accurate, unlike this particular 7.62x39 Vepr.

 

[PiggiePluggin]

So do you change scopes at the range?

 

[MeatAxe556]

So do you change scopes at the range?

Sometimes, sometimes not. But even if I do move the scope from the .308 to the 7.62x39, on either rifle it's bolted down tight. Side rails on both rifles seem secure.

The thing is, I'm not worried about hitting the bullseye. I'm just shooting for groups. The .308 will group consistently 2-3 moa. The 7.62x39 has the problems described above.

 

[PiggiePluggin]

So you are not taking the scope out of the rings? Jane you let somebody else shoot the rifle?

 

[MeatAxe556]

So you are not taking the scope out of the rings? Jane you let somebody else shoot the rifle?

No, the scope, rings and MI mount are transferred as a unit, from one rifle's side rail to another. Others shoot it with the same results: after 15 or so rounds accuracy goes from good to gone to hell.

Honestly, this is the only rifle I have that has this problem, other than a couple of finicky bolt action rifles that I use for hunting and only fire a few rounds a season out of.

Like the man said above, AKs are supposed to be bullet hoses, but you still need some reasonably consistent (if mediocre) accuracy. "Minute of Man" at least.

 

[PiggiePluggin]

Ya, I agree. I actually googled around to see if anybody else is having similar issues as you man. My last suggestion would be contact the company or take the gun to a gunsmith. There is only so much people can do on here for you man. Mostly just limited to suggestions.

I would say call the manufacturer and see what they say. If they stand by there product, you will be without the gun for a bit while they check it out. What's the worst they can say? If they won't, get the barrel scoped at a gunsmith.

Ib know the ak style weapon has a very strong following, but if you are truly interested in shooting groups maybe sell it and look.at a different style semi auto platform.

 

[MeatAxe556]

Ya, I agree. I actually googled around to see if anybody else is having similar issues as you man. My last suggestion would be contact the company or take the gun to a gunsmith. There is only so much people can do on here for you man. Mostly just limited to suggestions.

I would say call the manufacturer and see what they say. If they stand by there product, you will be without the gun for a bit while they check it out. What's the worst they can say? If they won't, get the barrel scoped at a gunsmith.

Ib know the ak style weapon has a very strong following, but if you are truly interested in shooting groups maybe sell it and look.at a different style semi auto platform.

Oh yeah, I'm pretty well acquainted with ARs, FALs, and a few other types. They each have their merits.

Over the years, I've gravitated to the AK as an all around "go to" weapon for self defense as well as a brush gun for hunting. They're extremely robust and very effective in 7.62x39, the ammo is cheap and they don't require much maintenance...and you're pretty much 100% certain it will go "bang" and cycle whenever the trigger is pulled. Accuracy in a good AK can be reasonable to good, enough to get consistent center mass shots at 200 yards and beyond with iron or red dot sights.

Honestly, this Vepr is the only AK I've had with problems holding what I'd call "reasonable" accuracy for the platform.

 

[K-tech]

Just a suggestion, try taking the scope out of the equation and use the iron sights. At least then you could rule out if the culprit is a scope issue.