Please help me solve 6 Creedmoor Velocity drop. UPDATE

[KMart]

I ran every test I could think of. When I tried new brass again then velocity on it also dropped.

Every 10-15 rounds I’m losing more velocity. I believe it has something to do with the barrel. This showed up shortly after cleaning. Use coated cleaning rods, bore guide, patch out/wipeout and their accelerator and a little Montana extreme copper remover with nylon brush. I’ve used this method on many barrels with no issues.

I sent barrel to Proof to check it out.

On another note I just spun a 24” Proof pre fit 7 Rem and after cleaning with above process at 57 rounds, it has lost 100 fps and continues to loose velocity the more I shoot.

I’ve only shot 20 since cleaning, will shoot few more and see if I can get velocity back if I foul the barrel.

Bit nervous about cleaning anymore proof pre fits until I figure this out

Unless I am completely wrong, Proof sells barrels that are carbon wrapped and a solid SS barrel.

Which barrel do you have?

 

[Doom]

I used nylon brush (no brass) wipe on patch out, their accelerator and Montana copper remover.

I can't say this is the issue but I am always suspicious of mixing products in a cleaning session. This is especially true of copper removers.

 

[dellet]

Measure both your bullets, and your bore. Bullets are easy, bore is more difficult. Not sure if you ever slugged a bore, but some thoughts.

An indicator of a bad bore, would be a loose spot in the barrel that you can feel while cleaning. Where you have constant pressure, and you feel the rod jump forward. Easy to think that it is rough/smooth spots in the new bore.

Not uncommon for a hand lapped barrel to be tight on both ends and be loose in the middle. The employment situation where Proof is located sucks, hopefully not a new guy causing some issues.

Sounds like you have a lot on your plate with the boys, but some things that might help figure it out.

Pushing a lead slug down a well oiled bore is not real difficult, as long as it’s only .001-2” over size. Trouble can be finding something. Splitshot fishing weights can work. Measure before and after.

If you can capture a fired bullet, one from a loose bore, will be black on the bearing surface like the outside of a case neck on a low pressure load.

 

[Unknown Marksman]

Unless I am completely wrong, Proof sells barrels that are carbon wrapped and a solid SS barrel.

Which barrel do you have?

I have 8 carbon and 2 steel. I’m having issues with 2 of the carbon. Haven’t tried to clean a steel on yet.

 

[Unknown Marksman]

I can't say this is the issue but I am always suspicious of mixing products in a cleaning session. This is especially true of copper removers.

It hasn’t been an issue in the past. But I will never mix different products in the future. Just for piece of mind if nothing else.

 

[Idaho-Lefty]

Might try, Peterson, Norma or, Starline, 6 Creed,.. LARGE Rifle Primer, Brass.
F-210M Primers and, a Lite JAM, on that, Bullet ( nice Square, .010- .015 marks, all around the Bullet ).
I have had, NO such, Velocity consistency, "Problems", in my 6 XC using,.. the above

 

[Unknown Marksman]

Measure both your bullets, and your bore. Bullets are easy, bore is more difficult. Not sure if you ever slugged a bore, but some thoughts.

An indicator of a bad bore, would be a loose spot in the barrel that you can feel while cleaning. Where you have constant pressure, and you feel the rod jump forward. Easy to think that it is rough/smooth spots in the new bore.

Not uncommon for a hand lapped barrel to be tight on both ends and be loose in the middle. The employment situation where Proof is located sucks, hopefully not a new guy causing some issues.

Sounds like you have a lot on your plate with the boys, but some things that might help figure it out.

Pushing a lead slug down a well oiled bore is not real difficult, as long as it’s only .001-2” over size. Trouble can be finding something. Splitshot fishing weights can work. Measure before and after.

If you can capture a fired bullet, one from a loose bore, will be black on the bearing surface like the outside of a case neck on a low pressure load.

I don’t want to mess with the barrel and cause any damage. I am going to Let proof look and see what they come up with.

Seems like the barrel is eroding with every shot. With 7 Rem pre cleaning 67.9 H1000 3 shot average 2948- after cleaning 2832.

After cleaning shot groups of 3 in this order
67.77 / 2860
67.89 / 2832
68.05 / 2817
69.96 / 2855

Going to shoot few today and see if fouling barrel helps. If not I’ll table it and wait until I hear back from Proof

 

[358WCF]

I haven't read the whole thread for detail, but it sounds a lot like different lot #s of H4350. In early 2020 I had 2 pounds of this powder bought about a month apart register 250fps difference on the same day. Identical charge weights loaded at the same sitting with all other components being from the same boxes.

 

[drop_point]

A couple things here:

That is an EXTREMELY low charge weight. Are you sure your numbers aren't off?

BR-4 primers are typically also slow in 6mm Creedmoor.

Chronographs can crap out on you or give bad readings. Did your trajectory change?

I thought I'd quote myself again because I never saw these answered.

 

[big5ifty]

Seems like the barrel is eroding with every shot. With 7 Rem pre cleaning 67.9 H1000 3 shot average 2948- after cleaning 2832.

That rate of barrel wear is impossible.

A barrel does wear after every shot, but it takes hundreds of rounds to be noticeable, and is definitely not noticeable shot to shot.

After cleaning shot groups of 3 in this order
67.77 / 2860
67.89 / 2832
68.05 / 2817
69.96 / 2855

I assume the preceding number is powder charge.

That is telling me you're past the maximum of slow burning powder that can burn in the barrel. The extra powder is leaving the barrel as muzzle flash.

As for the OP on 6CM, This is my opinion too :

I haven't read the whole thread for detail, but it sounds a lot like different lot #s of H4350. In early 2020 I had 2 pounds of this powder bought about a month apart register 250fps difference on the same day. Identical charge weights loaded at the same sitting with all other components being from the same boxes.

 

[Unknown Marksman]

I thought I'd quote myself again because I never saw these answered.

Chronograph is dead on. Confirmed not only with previous loads , but yesterday (5/6/2023) quickly worked up a load for a new barrel and shot an 600 yard F-class today. Drop was exactly 10.1 MOA.

Powder was dropped with SuperTrickler +/- .02 and only couple grains below listed max 42.2. Off the top of my head, Before I cleaned I was getting 2930 ish. After it dropped to 2578 over a 5-shot string.

I’ve sent it to Proof to see if it’s the barrel and if I might have been part of the problem

 

[drop_point]

Here is what you said before:

"On third firing of brass with 39.3 grain H4350 Velocity drops from 2900 to 2550. And there is carbon from the neck all the way to the end of the shoulder. Obviously I’m not getting a seal and loosing pressure."

Are you sure you didn't screw up in your notes somewhere?