Powder residue on cases bad

[eric32]

Can you post some pictures of the soot marks on the case from both powders

 

[Laurie]

Anybody with experience of loading and shooting the 6.5X55mm knows all about this issue, so it might be worth looking at this design for pointers. Since the problem is endemic in this cartridge with new high quality brass and factory cartridges, also neck-sized cases with a tight fit to the chamber shoulder have no apparent effect on the phenomenon, this suggests that that while mechanical chamber case / chamber issues are possible causes, they are unlikely. The answer there (6.5X55mm) is to increase the charge with this inherently lower pressure number, and/or change to a hotter primer. If all else fails, the powder grade is changed. A primer change usually cures the problem

Since this is no mild starting / low-pressure load, increasing charge weight and pressures doesn't look at all appropriate, so look at ignition. Since you're running small primer brass, your ignition may be marginal. We see ignition problems, serious enough to produce hangfires, in the UK with this cartridge's parent 6.5mm version with SP brass and some powders. As the 6mm version has a considerably higher case capacity to bore-area ratio (1,130 v 973) that usually decreases cartridge load-tolerance further and makes life harder in this and other respects. What are your ES numbers like as large values are often the first sign of ignition problems?

Try some other primers, but you may have to switch to large primer brass or another powder.

 

[whatsupdoc]

Stop with the load is too lite, 3150 FPS in a 6mmCreedmoor is a FULL POWER LOAD PERIOD, it is faster
than a factory load.

There is nothing wrong with the OP's choice of components as a matter of fact that combination is probably
the most common combination for the 6mm creed.

His issue lies elsewhere.

 

[DiffEQ]

When I have experienced powder burns back to the case head, it was due to either the case needing to be annealed or my chamber being bad.
Seems to me, this is a new occurrence, yes? i.e. you have fired many rounds without the powder residue, and now the last 50 or so now have the markings? If so, ask yourself, "what has changed"?
New Powder? * New lot of bullets? * New primer batch? * X number of firings since last anneal? * Big change in leade since you last measured?

• Inspect your chamber with a FO camera. Clean that sucker if it's got gunk.
• Anneal all your brass so you're starting with a base condition.
• A test I would run would be to make two batches, ten rounds each, starting at 40 gr. of powder and increasing by 0.3gr each round. The first batch is normal neck tension (i.e. you do the same loading), the second batch is either tighter neck tension or you crimp.

 

[Matt_3479]

@Matt_3479

Any lucky with the cases or a repeatable soot pattern?

I had some similarities but not a bunch. Some had more soot on the base, some the neck and shoulder was covered, some the body was just black and others it was light residue.
As far as being crooked I couldn’t distinguish if they were. I tried my best but didn’t seem to be the issue.

 

[Matt_3479]

No. Don't do that.

Low pressure would be an obvious cause of your problem. But that would also be seen very clearly in your velocity. You mentioned in your first post you were getting 3150 fps. Low pressure is not your problem.

I mean obviously work up until pressure. Cause at that speed there is 0 pressure signs. Primers look perfect, bolt lift is totally normal.

Low pressure is the problem, but not from the amount of the powder charge.
The output of the primer firing is moving the bullet out of the case mouth to soon. Low neck tension/bullet hold.
A long free bore/throat adds to the problem.

On firing, the bullet needs to be in contact with the rifling , while the full diameter bullet shank is still in contact with the case mouth. (Bullet jam)

The start pressure may be low because of the small rifle primer & tiny flash hole (if brass has it?) https://forum.accurateshooter.com/threads/flash-hole-size.3966076/#:~:text=The standard dimension for Lapua,0590″.


My best guess, from what i have seen online.

I had the bullet jammed on a few and they still showed the same thing. And worked backwards. There was still plenty of bullet in the neck too.

 

[eric32]

Yea they look straight and the pattern doesn't seem to be consistent.

Next find some factory ammo and shoot it and see how they come out if you get the same result. I would send it back to get inspected.

 

[Matt_3479]

Are you removing the primers on a fired case when you check the base-datum line?

Honestly, it just looks like the powder is too slow. -Al

yes always do. Any measurements I take are without primers.

I know why your saying that but don’t you think it would be a more occurring problem then amoungst other shooters running any form of creedmoor. I mean it’s the most popular powder run in the creedmoor, 260/243 case, even smaller cases like the 6.5/6x47, and xc cases and I’ve never seen smaller cases have this problem

 

[eric32]

Also it could just be a shit lot of brass.

Another course of action is if the factory ammo shows no soot. Reload it with the same load data and test again.

That will isolate either the chamber or brass.

 

[Matt_3479]

Stop with the load is too lite, 3150 FPS in a 6mmCreedmoor is a FULL POWER LOAD PERIOD, it is faster
than a factory load.

There is nothing wrong with the OP's choice of components as a matter of fact that combination is probably
the most common combination for the 6mm creed.

His issue lies elsewhere.

That’s kind of my thought too. Like that’s fast, but i have no problem increasing powder charge slowly until signs of pressure but I can’t imagine that being the case.

When I have experienced powder burns back to the case head, it was due to either the case needing to be annealed or my chamber being bad.
Seems to me, this is a new occurrence, yes? i.e. you have fired many rounds without the powder residue, and now the last 50 or so now have the markings? If so, ask yourself, "what has changed"?
New Powder? * New lot of bullets? * New primer batch? * X number of firings since last anneal? * Big change in leade since you last measured?

• Inspect your chamber with a FO camera. Clean that sucker if it's got gunk.
• Anneal all your brass so you're starting with a base condition.
• A test I would run would be to make two batches, ten rounds each, starting at 40 gr. of powder and increasing by 0.3gr each round. The first batch is normal neck tension (i.e. you do the same loading), the second batch is either tighter neck tension or you crimp.

honestly I don’t think it’s a new occurrence. I recall it happening pretty much from the second firing. Unfortunately I had a few guns finished up so fast back to back I haven’t shot it in a while and recently I wanted to spend more time with it and get all my rifles lined up for load work and it just reminded me. I asked locals the first time it bothered me but now I’m not sure what’s going on as I thought I had tried everything the first time around, put it away and forgot about it.

i did an extremely thorough clean with a bore scope handy. Will pick up a box of factory to try to eliminate my chamber or my reloads. If it doesn’t happen I’ll anneal regardless and try again. If not I might start with a new batch of brass

 

[Matt_3479]

Also it could just be a shit lot of brass.

Another course of action is if the factory ammo shows no soot. Reload it with the same load data and test again.

That will isolate either the chamber or brass.

im starting to wonder the same thing! I hope not, alpha brass is 160 bucks for 100 in Canada lol.

im going clean the rifle again, clean brass and anneal. Pick up a box of factory this week, and test it. If all comes back clean; then I’ll load the factory brass and my alpha brass with same load and go shoot. If one comes back clean and the other covered in soot I’ll throw out the alpha and start with a fresh brass of brass. If both come back dirty, guns going back to the smith

 

[eric32]

Yup solid plan, I would contact alpha and send it to them for inspection or at least a replacement lot

 

[AlNyhus]

yes always do. Any measurements I take are without primers.

I know why your saying that but don’t you think it would be a more occurring problem then amoungst other shooters running any form of creedmoor. I mean it’s the most popular powder run in the creedmoor, 260/243 case, even smaller cases like the 6.5/6x47, and xc cases and I’ve never seen smaller cases have this problem

It certainly could be brass that's so hard, thick....or both....that it won't seal correctly. That will give the same 'look'....sooty cases. If the factory ammo cures the 'sooty' case problem, you know it's the brass. -Al

 

[searcher]

so your saying to keep ramping up powder charge until i hit signs of pressure and hopefully this goes away! If it doesn’t, then look at other avenues. But as far as your concerned I should overly worry about it as long as I’ve checked the number of things off the list;

- light load
- head space
- neck tension
- work hardened brass
- annealing.

and if it still happens the just shoot it as it is and run with dirty brass. I mean if it’s not causing harm, and I’ve done everything I know of correctly I’m okay with it. I just want to make sure I’m not missing something and if I am to fix the issue.

I mean out of small chance this barrel is insanely fast and I am below pressure I’ll ramp it up. But 105’s at 3200-3250 sounds insane

As I said - you are getting pretty high velocity for this to be considered a 'light load" normally - but you are getting signs that it is not burning hot for that powder/bullet combo in your particular barrel. Others might suggest differently, but, lacking any signs of high pressure on your brass (ie; expanded bases, flattened or pierced primers, difficult bolt lift, etc.), I'd continue up the powder column in 3/10th max increments, watching for signs of pressure all along the way. Even if the powder residue disappears, I'd continue up the ladder at least another 1 1/2 grains, just so you know that after you back it off at least 1 1/2 grains - you are not finding yourself in the danger zone on a much hotter day in the field. I sincerely doubt the residue has anything to do with your annealing or brass hardness. if you over-anneal, your brass is extra soft - and will easily seal the gasses. If the brass is so hard that it won't seal, you will likely be getting cracked necks on many pieces of brass - a good indicator of brittle brass. The lack of seal with hard brass would also be contributed by a light load. At 30,000 PSI, it doesn't take THAT much to make that little brass neck expand. Neck tension will also likely have nothing to do with it. Some guys leave their powder in the powder measure and find, after even a short time (several days), their powder burns much slower after absorbing some humidity. It can also cause this condition to the point where you can't get enough powder in the case to make it burn as hot as it should. If you have an unopened container of powder, you can switch powder just to eliminate that as a possible source or contributor to the problem. As for trimming your brass length - you can usually over-trim your brass by quite a bit (at least .010") before gas leakage would ever be an issue - but if you don't chamfer the inside and outside of the brass - that can cause gas leakage. If your brass overall length is within .010" or so of trim length as published - that won't be the problem - assuming your brass is not much longer than it should be. Good Luck!

 

[okie]

Can you post some pictures of the soot marks on the case from both powders

Me? I can try. I handled them quite a bit...

 

[243winxb]

Matt_3479

Fired Case neck outside diameter should not be larger then .279" by the SAAMI drawing.
What does your fired brass necks measure?

Compare factory to reloads.

 

[243winxb]

https://apps.dtic.mil/docs/citations/ADA622138

The primer is capable of producing enough force to
debullet the projectile and begin the engraving process prior to any significant propellant burning.

Im running cci 450 primers

Increase neck tension/bullet hold, so bullets don't move to soon.