Accuracy loss at 400 rounds.

[Southern Custom]

• #1

I have some questions for the guys who have been through all of this and come out the other end. I’m not new to reloading but I’m only a year in to seriously loading for a precision rifle.
So here’s my story. I have a 6mm Creedmoor Bergara HMR pro rifle that has been shooting under .5 without effort and .3 all day as long as I’m on my game. That’s the best I could hope for out of a factory Bergara and I’m happy with it. At the 400 round mark I suddenly started getting accuracy issues. 3/4”-1” groups. Best I could do yesterday was .5. I was just about to start shooting 600yd field precision matches and 1” won’t cut it.
I’m looking for advice on how to proceed. I’ve ruled out gun/scope torque etc. I’m fairly certain this is a powder/barrel issue.
Ive been shooting IMR 4350, Peterson brass, Hornady 108 ELDM. The node I’ve been at was around 2950fps with 40.4g. Gun liked bullets seated 15thou off lands. I have 2thou of throat erosion so far.
At around 400 I suddenly jumped 100fps to 3050. This also came when I started a new 8lb jug of IMR 4350 so there’s that. Last week I blew 1 primer and started getting occasional sticky bolt. Also Ejector marks on brass at 3100.
Just spitballing I switched to H4350 at the same 40.4 which I’ve done before with only 25fps speed increase. Now that same load gives me 3100fps and minor pressure signs. That’s nearly 100-125 faster than that powder switch used to give me. And this in mild 80deg temperatures.
Barrel was cleaned of copper at around 250 and again at around 450. I’m at 500 rounds Last 100 rounds have me totally scratching my head. At 400 rounds and shooting well, I had just decided to do a ladder test with seating depth to see if I was in the best place. This was when things started going south and nothing, even my go to load, seems to work.
Barrel was cleaned using Barnes to remove copper. Wet patches run through and left for 10min twice. Bergara barrels are lapped and I never seem to get any copper buildup but without a bore scope I’m going on my patches for signs.
So my questions are, can I have a serious carbon ring at 400 rounds? With a new jug of IMR 4350 should I be redoing a ladder test from say 39g to 40.4. (First work up showed 3 nodes at 39.6, 40.4 and 41.5) there’s no way I could even shoot 41.5 now considering I’ve sped up 100fps. If the gun seems to like 2950 should I try and get back to that speed? Can there be that big of a discrepancy between powder lots?
I have a bore scope on the way so I’ll be able to get a better look at the bore. It’s possible my barrel is not as clean as I think it is given my fairly gentle cleaning regimen.
Just trying to get some confirmation I’m approaching this from the right direction so far. I have a new Brux barrel waiting in the wings bu I’d planned to milk this factory barrel for all it was worth while I learn.

 

[straightshooter1]

• #1

I have some questions for the guys who have been through all of this and come out the other end. I’m not new to reloading but I’m only a year in to seriously loading for a precision rifle.
So here’s my story. I have a 6mm Creedmoor Bergara HMR pro rifle that has been shooting under .5 without effort and .3 all day as long as I’m on my game. That’s the best I could hope for out of a factory Bergara and I’m happy with it. At the 400 round mark I suddenly started getting accuracy issues. 3/4”-1” groups. Best I could do yesterday was .5. I was just about to start shooting 600yd field precision matches and 1” won’t cut it.
I’m looking for advice on how to proceed. I’ve ruled out gun/scope torque etc. I’m fairly certain this is a powder/barrel issue.
Ive been shooting IMR 4350, Peterson brass, Hornady 108 ELDM. The node I’ve been at was around 2950fps with 40.4g. Gun liked bullets seated 15thou off lands. I have 2thou of throat erosion so far.
At around 400 I suddenly jumped 100fps to 3050. This also came when I started a new 8lb jug of IMR 4350 so there’s that. Last week I blew 1 primer and started getting occasional sticky bolt. Also Ejector marks on brass at 3100.
Just spitballing I switched to H4350 at the same 40.4 which I’ve done before with only 25fps speed increase. Now that same load gives me 3100fps and minor pressure signs. That’s nearly 100-125 faster than that powder switch used to give me. And this in mild 80deg temperatures.
Barrel was cleaned of copper at around 250 and again at around 450. I’m at 500 rounds Last 100 rounds have me totally scratching my head. At 400 rounds and shooting well, I had just decided to do a ladder test with seating depth to see if I was in the best place. This was when things started going south and nothing, even my go to load, seems to work.
Barrel was cleaned using Barnes to remove copper. Wet patches run through and left for 10min twice. Bergara barrels are lapped and I never seem to get any copper buildup but without a bore scope I’m going on my patches for signs.
So my questions are, can I have a serious carbon ring at 400 rounds? With a new jug of IMR 4350 should I be redoing a ladder test from say 39g to 40.4. (First work up showed 3 nodes at 39.6, 40.4 and 41.5) there’s no way I could even shoot 41.5 now considering I’ve sped up 100fps. If the gun seems to like 2950 should I try and get back to that speed? Can there be that big of a discrepancy between powder lots?
I have a bore scope on the way so I’ll be able to get a better look at the bore. It’s possible my barrel is not as clean as I think it is given my fairly gentle cleaning regimen.
Just trying to get some confirmation I’m approaching this from the right direction so far. I have a new Brux barrel waiting in the wings bu I’d planned to milk this factory barrel for all it was worth while I learn.

Yeah, if you're giving your barrel "fairly gentle cleaning regimen", I'd say it's time to be more rigorous and get it really clean. Depending on what the patches look like seldom give you a good idea of what's in the bore. I think once you see through a bore scope, you'll see just what's still there with your gentle cleaning. And most likely, you're going to have to work on the carbon ring. I'd recommend using Flitz Bore Cleaner and follow it's instructions. It does a very good job for me, especially if I feel I need to get my bore throat free of carbon and it actually does it relatively easy.

As you seem to be aware already, going to a new lot of powder is likely contributing to your issue also. So, you'll probably have to make some minor changes to your load, like . . . a little less powder like you're thinking to where you MV is about where you were (though I don't feel you need to change your seating depth).

 

[spife7980]

Yes and no to everything but it all sounds possible. Working it up and seeing where it’s at now is the only way to get actual answers to your questions.

 

[Southern Custom]

While I won’t have a bore scope till Thursday, I am a gun engraver and I do have a microscope. I yanked my brake and took a look down the muzzle and sure enough. Fairly heavy line of copper on the lands. Between that and the potential for a carbon ring and I may have found my issues. That’s the only thing that explains that big of a pressure spike with my old load. Most guys are running between 40 and 41.5 and I can’t even get close to that right now. I did a more thorough clean today and scoping it on Thursday should clue me in to how well I did.

 

[rancher5]

While I won’t have a bore scope till Thursday, I am a gun engraver and I do have a microscope. I yanked my brake and took a look down the muzzle and sure enough. Fairly heavy line of copper on the lands. Between that and the potential for a carbon ring and I may have found my issues. That’s the only thing that explains that big of a pressure spike with my old load. Most guys are running between 40 and 41.5 and I can’t even get close to that right now. I did a more thorough clean today and scoping it on Thursday should clue me in to how well I did.

I bet a taco you'll see plenty of shiny carbon in your barrel , once you bore sight it, 300-400 magic number for everything going to hell in that caliber, Good luck,

 

[Baron23]

While I won’t have a bore scope till Thursday, I am a gun engraver and I do have a microscope. I yanked my brake and took a look down the muzzle and sure enough. Fairly heavy line of copper on the lands. Between that and the potential for a carbon ring and I may have found my issues. That’s the only thing that explains that big of a pressure spike with my old load. Most guys are running between 40 and 41.5 and I can’t even get close to that right now. I did a more thorough clean today and scoping it on Thursday should clue me in to how well I did.

I really like Bore Tech Copper Remover or Patch Out to get copper out....works well and easy.

I have never used Barnes.

Just a thought

 

[supercorndogs]

Yes, you can have a serious carbon rings at 400rds. They can be a PIA. Makes @Dthomas3523 and his witch doctor cleaning methods seem pretty smart. What??? Clean before problems arise?!?!?! Just crazy enough to work.

If you don't get it scrubbed all the way out, it will come back faster than before. I wonder of it does it worse in hot rod calibers. I have never had a problem with them on 223 or .308.

 

[Southern Custom]

I bet a taco you'll see plenty of shiny carbon in your barrel , once you bore sight it, 300-400 magic number for everything going to hell in that caliber, Good luck,

No shit I measured to lands and got 2.350 a few days ago. Did a CLR job on the throat and just hit 2.365. Looks like that may have been the deal. We’ll see.

 

[rancher5]

No shit I measured to lands and got 2.350 a few days ago. Did a CLR job on the throat and just hit 2.365. Looks like that may have been the deal. We’ll see.

Defiantly buy a scope 40 bucks now, if you just did that at the throat, Hope your a strong dude, you'll be cleaning for a while, Good Luck.

 

[spife7980]

I will run wet patches down the barrel to get it soaking and softening for awhile the whole way but then I make sure a patch is super saturated and then leave it jammed in the throat ensuring that there is solvent wicking on to the whole area. Then after an hour or so a few spins of a brush or a super tight patch to really scrub it out.

I like wipe out for a good easy frequent clean every couple hundred and then I do a bore tech c4 and c2 solvent bath at every five hundred or so to make sure it gets good and clean. I say so long as you don’t have steel rod running against barrel steel that you can get pretty aggressive with your patches and brushes to dig that carbon out without hurting much with the listed cleaners. Well basically every popular cleaner aside from the abrasives.

 

[straightshooter1]

No shit I measured to lands and got 2.350 a few days ago. Did a CLR job on the throat and just hit 2.365. Looks like that may have been the deal. We’ll see.

My .308 currently has 4195 rounds through it and I've gone a couple times to nearly 600 firings (typically, it's about 200) before cleaning and not had the problem you've described. But, when I go that long without cleaning, there is definitely quite a carbon ring build up. Because I always trim by brass to the same length every time I size them, my carbon ring build up hasn't given me an problem except in trying to remove it when there's a heavy build up and I found the Flitz Bore Cleaner makes short work of it compared to may other things I've tried (including CLR).

Typically, when cleaning with 200 rounds or less, I don't try to remove all the copper fowling, but to get the carbon out (except some that's deep into the firecracking), which does help in not having to foul the bore before expecting to get my POI's where they're supposed to be. And in this case, the copper fowling left is mostly in the throat area and a little forward of it. Doing this, my first cold bore shots are on the money.


Let us know if cleaning that carbon out gets you back to where you were.

I still wonder if it'll get you all the way back given your new lot of powder. New lots of powder has made me make some adjustments either in how much powder or in my seating depth to get normal my results back.

 

[clcustom1911]

Yes, you can have a serious carbon rings at 400rds. They can be a PIA. Makes @Dthomas3523 and his witch doctor cleaning methods seem pretty smart. What??? Clean before problems arise?!?!?! Just crazy enough to work.

If you don't get it scrubbed all the way out, it will come back faster than before. I wonder of it does it worse in hot rod calibers. I have never had a problem with them on 223 or .308.

Yeah, the whole "dont clean until accuracy falls off" is like "dont change your engine serpentine belt until it shreds".

Preventive maintenance.... is a thing.

 

[Southern Custom]

Yeah, the whole "dont clean until accuracy falls off" is like "dont change your engine serpentine belt until it shreds".

Preventive maintenance.... is a thing.

I’m learning this the hard way. I’m looking more and more towards how F class shooters treat their rifles and amongst them, cleaning... is a thing. This whole treat your barrel like a baby and don’t touch it deal has bitten me in the rear big time. The serpentine belt broke and now I have bent rods to deal with. Hopefully this will be a lesson to other guys shooting barrel burners like mine.

 

[clcustom1911]

I’m learning this the hard way. I’m looking more and more towards how F class shooters treat their rifles and amongst them, cleaning... is a thing. This whole treat your barrel like a baby and don’t touch it deal has bitten me in the rear big time. The serpentine belt broke and now I have bent rods to deal with. Hopefully this will be a lesson to other guys shooting barrel burners like mine.

You did pick a barrel burner. I do 6.5 creed, so the issue isn't as bad, but it could be if I didn't clean. And, IMO, you don't need to go F-class level cleaning unless you're expecting FCalss performance out of an FClass gun. They clean constantly because that's how their loads were developed for maximum accuracy. So, they maintain that clean condition in their bore to maintain that consistency.

And for me, "cleaning" is running a bore snake 3-4 times soaked in Hoppes 9, then running a couple dry patches every 75-100 rounds or so. I have a bore scope and only use it to check for carbon ring shit. I could care less about anything else because it shoots consistently. I never fully clean everything out so my rifles are pretty much always "kinda dirty". I dont have a clean bore zero vs dirty bore zero, or seen the need to shoot a few rounds to dirty my bore. I dont shoot at that level of precision anyway. I'm a "minute-of-50% IPSC-plate angle" shooter. Which, I love shooting 50% IPSC plates out at like 900 because when you finally put full size out there, it looks like the side of a barn!

I digress...

But that's just me. I'm also the kind of guy that cleans my AR's once every 500-600 rounds... maybe... and with only a bore snake too LOL.

 

[bfoosh006]

Sorry if I missed this....

How many times have the brass case been reloaded ?

And have the case necks been annealed recently ?

 

[Dthomas3523]

If anyone is wondering about cleaning and accuracy and such. Here is a pic of target after I took my dasher apart. Scope off action, action out of stock, barrel off action, brake off barrel. Then did my soak and brush method.

Put it all back together. The lower three shots are the first three out of a clean barrel. The rest are after those three. Didn’t touch the turrets. Just cleaned and bolted it all back together.

 

[Baron23]

So, for those of us who are not yet as competent at pulling actions and barrels as some of you folks, what is the best method to try to get at potential carbon ring.

Oversized brush, chucked in a drill, sacrifice a virgin (good luck finding one) to the gods and hope, or...???

 

[spife7980]

So, for those of us who are not yet as competent at pulling actions and barrels as some of you folks, what is the best method to try to get at potential carbon ring.

Oversized brush, chucked in a drill, sacrifice a virgin (good luck finding one) to the gods and hope, or...???

Soak it with a wet patch of a good solvent to get it weakened and then brush it out, yeah. Maybe do a couple cycles if its really bad.

 

[Baron23]

Soak it with a wet patch of a good solvent to get it weakened and then brush it out, yeah. Maybe do a couple cycles if its really bad.

Thanks. I do use Bore Tech Carbon Remover so hopefully I’m doing ok.

It certainly does seem that pulling the barrel is really the way to see if you have a ring and best way to get access to it.

Shotguns were so much easier. Chuck an oversized brush into a drill and wail away cleaning the chamber and forcing cones.

 

[TheOfficeT-Rex]

So, for those of us who are not yet as competent at pulling actions and barrels as some of you folks, what is the best method to try to get at potential carbon ring.

Boretech c4, sopping wet patch and let it sit. I find I do a lot less patching if I can loosely send 2-3 very wet patches through and let them soak for 10 minutes, then dry patch and repeat. Same for the ring, but use a mop or a patch on the outside of a brush to get the c4 to soak up there.

If it's really bad, I've plugged the muzzle with a piece of rubber, stood the rifle up inside of a garbage can, and filled the whole tube up to let it soak.

Oversized brush, chucked in a drill, sacrifice a virgin (good luck finding one) to the gods and hope, or...???

The virgin, while not strictly necessary, will reduce the amount of elbow grease required.


ETA: I know it's the new hotness, but I'm dubious about CLR. It's not safe on all finishes, nitride being one of them. YMMV.

 

[Southern Custom]

So while waiting on a bore scope I went through a CLR then Barnes CR10 routine to get the carbon and copper out. I really cleaned this time. Or so I thought. Afyer this I measured to the lands and Surprise! I thought I had only eroded 2 thou. After cleaning that number went from 2.350 up to 2.365. So yea as someone mentioned above, the carbon was giving me a false reading. I’ve eroded 18thou over the 400 rounds.
The borescope arrived today and I found I still had copper on the lands. Not a ton but leftover smears and flakes. Luckily my carbon ring was almost completely gone so I apparently did ok there.
I went through one more Barnes job to remove the rest of the copper, did a quick Semichrome patch to polish things upjust a touch and hereare the results along with the patches that came out from the second go around.
The first shot is the throat with ring gone. Second is midway up the bore. Lands are squeaky clean now. Also some groups from my last range trip. Not typical for this gun. We’ll see what she does in a few days. This has definitely been an eye opening experience. Hopefully she shoots and I can save that Brux barrel for another day.

 

[Dthomas3523]

Adjust your seating depth if it doesn’t go back to shooting.

 

[Baron23]

Same for the ring, but use a mop or a patch on the outside of a brush to get the c4 to soak up there.

Do you soak the mop, push it in just far enough to reach the throat, and then let it sit in there like that?

As for getting carbon out, yes...I use C4 on very wet patches and it works very well. But cleaning up carbon ring....eh, that's a little out outside of my experience so far so I do appreciate the tips.

Cheers

 

[TheOfficeT-Rex]

Do you soak the mop, push it in just far enough to reach the throat, and then let it sit in there like that?

I usually don't leave the mop in, but it probably wouldn't hurt. I think the key is getting the carbon wet, and letting it soak. Same as running a few wet patches and letting them sit when you clean the rest of the barrel, the chemical needs some amount of time to break down the carbon.

It will likely take a couple of soaks, as the outer layers of carbon is all that is wet at any one time, and you won't be leaving a large excess of solvent to carry away the carbon layers - It's going to be a lot slower than the fill the bore method.

To be honest, I have never had to use a drill either, just turning the brush on a cleaning rod has been enough after soaking a few times.

 

[Baddog 0302]

I usually take 3 rifles to the range to make the most of my time,when I'm through for the day with one rifle I give it a
shot of THIS, and repeat with following other rifles. And before putting them into their gun cases I cover the muzzles with a piece of pvc tubing with paper towels stuffed in. Really convient with the 308 AR's

 

[Dthomas3523]

I usually take 3 rifles to the range to make the most of my time,when I'm through for the day with one rifle I give it a
shot of THIS, and repeat with following other rifles. And before putting them into their gun cases I cover the muzzles with a piece of pvc tubing with paper towels stuffed in. Really convient with the 308 AR's

That better not be an affiliate ID at the end of that link.......

 

[Southern Custom]

Adjust your seating depth if it doesn’t go back to shooting.

I’m going to start 20 off and go from there. We’ll see. It always shot well pretty close.

 

[Baddog 0302]

That better not be an affiliate ID at the end of that link.......

IT IS NOT,
just the easiest way for me to add my $0.02. As soon as I use up my collection of 6MM bullets this Savage bbl. will become a tomato stake , and it will be replaced with a $$$ 308 Bbl. with a Palma chamber.

 

[Southern Custom]

Here’s an update for my 6mm. After a thorough deep cleaning, she’s back. Thanks to everyone who helped point me in the right direction. The simple fact is that while I’ve been reloading for over 20 years, I have just never shot enough center fire to have ever experienced an issue like this and has no clue what to look for.
The issue was indeed a carbon ring. Coupled with far more copper than I thought I actually had. The bore scope didn’t lie and was money well spent. Also a great learning experience. The main thing that I’ve learned is that all of this “don’t clean it, just shoot it” talk is very much caliber dependent. What you can get away with in a .308 is not the same by any stretch for a 6mm Creedmoor.
The rifle is back to shooting .3-.5moa. No more pressure signs and speed is back down in the normal range with consistent SD and ES. The only headache is that I’m having to redo all my load data for the gun. My old powder charges are a bit off and seating depth is certain a bit off as well. Normally this would just mean a lot of shooting and fun at the range. But in these times it means staring at my stock of primers and powder and thinking hard about how much I want to burn to get the consistency back that I had.

 

[Dthomas3523]

You said it went back to .3-.5 with stable velocity numbers. Then state you are having to redo your loads?

What isn’t working that makes you think you need to revisit load development?

 

[straightshooter1]

The main thing that I’ve learned is that all of this “don’t clean it, just shoot it” talk is very much caliber dependent. What you can get away with in a .308 is not the same by any stretch for a 6mm Creedmoor.
The rifle is back to shooting .3-.5moa. No more pressure signs and speed is back down in the normal range with consistent SD and ES.

It seems to me the only caliber that one might say “don’t clean it, just shoot it” would be the 22LR. But even then, one may not have clean the bore, but definitely need to keep an eye out for the carbon ring to maintain accuracy.

I've gone as much as 800 rounds on my .308 without cleaning the bore, without any effect on accuracy or change in velocity, BUT . . . I did clean the chamber and removed the carbon ring evey 150-200 rounds.

The only headache is that I’m having to redo all my load data for the gun. My old powder charges are a bit off and seating depth is certain a bit off as well. Normally this would just mean a lot of shooting and fun at the range. But in these times it means staring at my stock of primers and powder and thinking hard about how much I want to burn to get the consistency back that I had.

If the new powder isn't different by much, you should only have to make sum adjustments with seating depth . . . huh???

OR. . . if you have a tuner mounted then the adjustment is easy enough.

 

[Southern Custom]

You said it went back to .3-.5 with stable velocity numbers. Then state you are having to redo your loads?

What isn’t working that makes you think you need to revisit load development?

I loaded up a few different charges and guessed at seating depth. A couple of good groups doesn’t mean it’s dialed in. I need to find consistency in a good node.

 

[Dthomas3523]

I loaded up a few different charges and guessed at seating depth. A couple of good groups doesn’t mean it’s dialed in. I need to find consistency in a good node.

I’m still not following. You had the rifle dialed in before the cleaning correct?

If so, you shouldn’t need to be revisiting much more than seating depth.

There’s not much more to this stuff than stable velocity and acceptable groups. And you can tune them separately from one another if you choose to.