Soot on neck and shoulder 6.5x47L

[Aroy87]

Hello Everyone;

I have a question regarding my cartridges having soot down even past the neck/should junction.

Here is some data for my rifle.

Savage SA, Criterion Barrel, 28", 1:8.
Forrester Bump Die.
I'm currently running 140gr Nosler RDF over 37.8gr of Varget, MV average is about 2835 at last range session (75-80 degrees F, 850 ft)

Brass: Lapua
Primers: CCI 450 Small Magnum

I've read in other places that brass may not be sealing properly due to a light load but this seems unlikely given the over max load.

I'm on my 3rd firing and did not seem to have as much of an issue with soot in the prior firings.

I have no pressure signs and liked the velocity but not my SD seems to be opening up and it appears to correlate with the soot on the shoulder.

My highest SD prior to my last shoot session was 7.2 for a 10 shot string, how it is hovering around 10 with a really large ES.

If anyone has experience with this particular issue feel free to share, if you need more information I can gladly give it.

Thanks

 

[DunInOne]

Mine do the same they've been annealed and es over 10 shots was 15fps... accuracy has been outstanding so not sure if it really matters but hope some others chime in

 

[DunInOne]

Also want to add I'm shooting suppressed!

 

[CavReconScout]

I anneal mine every third reload and I get soot after the third time. I anneal and then all is good until I hit three reloads again. I just thought it was my load but sounds like yours is doing the same thing. I am not seeing any increase in ES or SD though. Difference between our loads I am using 140 hybrids and H4350 running 2815fps.

 

[RampedRaptor]

I also am curious what may be causing increased soot. My 6 creed loads are covered with soot in the neck and shoulder junction. Lapua brass and I anneal every firing. Plenty of pressure and the loads are very accurate.

 

[Milo 2.5]

I also am curious what may be causing increased soot. My 6 creed loads are covered with soot in the neck and shoulder junction. Lapua brass and I anneal every firing. Plenty of pressure and the loads are very accurate.

Going out on a limb here, I'd bet the neck in your chamber slightly oversize, not getting a good seal, if everything else works it is a non issue.

 

[Milo 2.5]

Hello Everyone;

I have a question regarding my cartridges having soot down even past the neck/should junction.

Here is some data for my rifle.

Savage SA, Criterion Barrel, 28", 1:8.
Forrester Bump Die.
I'm currently running 140gr Nosler RDF over 37.8gr of Varget, MV average is about 2835 at last range session (75-80 degrees F, 850 ft)

Brass: Lapua
Primers: CCI 450 Small Magnum

I've read in other places that brass may not be sealing properly due to a light load but this seems unlikely given the over max load.

I'm on my 3rd firing and did not seem to have as much of an issue with soot in the prior firings.

I have no pressure signs and liked the velocity but not my SD seems to be opening up and it appears to correlate with the soot on the shoulder.

My highest SD prior to my last shoot session was 7.2 for a 10 shot string, how it is hovering around 10 with a really large ES.

If anyone has experience with this particular issue feel free to share, if you need more information I can gladly give it.

Thanks

Is the soot on your shoulder showing up as a full ring, or half moon shape?

 

[RampedRaptor]

Going out on a limb here, I'd bet the neck in your chamber slightly oversize, not getting a good seal, if everything else works it is a non issue.

Thats the only thing I thought to contribute it to also.

It's definitely not as tight as my previous chambers and I hate working my brass more than I have to. Fired brass vs sized and seated bullet = .005". Add .001 for brass springback and im working with a .006" chamber difference. This is with unturned Lapua.


op I didn't intend to make this thread about me. Do you know the difference in your neck OD on a fired round vs a sized and bullet seated round? Also have you tested if annealing every time eliminates the chrono findings you've identified?

 

[Aroy87]

I'll answer in the order I was asked:
1) I have no means of accurately the neck size unless I borrow some pin gauges from work use them for GO/NO check.
2) @Milo2.5: I am getting half moons and partials, never over the entire shoulder.
3) @RampedRaptor: I have not checked the difference between the fired rounds and the sized rounds, I will give it a shot when I get a chance (maybe in a week or so)
3.1) I have not annealed my brass as of yet, I'd prefer to make a machine to do it so it is a bit more consistent but I can try it manually and check results.

My most accurate firing was my first firing of any of the brass, I did not even size it, I just loaded them with powder, primer and projectile and went to town, my lowest SD was ~5.4 for 10 shots. It has been growing with nothing else changing.

I'll do a bit more digging, thanks for the suggestions.

 

[Milo 2.5]

I'll answer in the order I was asked:

2) @Milo2.5: I am getting half moons and partials, never over the entire shoulder.


I'll do a bit more digging, thanks for the suggestions.

Ok, I had this same issue on a 6x47, when I borescoped the barrel, it was apparent that the 45deg shoulder angle cut leading into the barrel was washed out for about a third of the way around.
But at the same time it became apparent I had issues, the gun dumped pressure and lost velocity and accuracy, there was no bringing mine back, barrel was tits up in about 800rds. I chalked it up to a softer barrel, or softer right in that area, this happened fast also.

 

[6.5x47 Guy]

I had the same issue, I increased neck tension to .003" and it mostly went away. Still light soot halfway down the neck but nothing near the shoulder anymore. More more neck tension allows the case to expand and start sealing sooner before the bullet is released.