Soot on shoulder and pressure signs(?)

[dgeesaman]

0.011 per side (+/- 0.2655) or 0.268" loaded?

Barrel length?
Bore Diameter?
Shoulder set back by die clicking or measured bolt drop on sized brass?

Charge seems appropriate for those velocities, but the speed is comparably low.

The explanation of not sealing fast enough sounds reasonable enough, but not sure how useful it is if you're already wearing out primer pockets with little room to explore higher charges.

Where you live (altitude, humidity, etc.) can influence where your gun will run comfortably and tune. A good example of "what one famous guy did at a specific location with a specific powder and bullet" not being applicable everywhere.

You caught my math error and I do get .268/.2685 loaded diameter (standard micrometer) and .0120/.0125 per side (tubing micrometer with a pin anvil). I measure .2433 at the pressure ring.

Barrel is 26" long, .236 / 5R. Shoulder bump is set by bolt close with no resistance plus .0015". I have no idea how many "turns" the die is set to but I have the lock ring set to produce that comparator length consistently.

I suppose the mystery still boils down to why the neck isn't sealing, and what I can do about it as I'm now planning to back down charges further. Mr Glantz is suggesting more aggressive annealing and leaving a bit of unsize neck length.

My non-expert but experienced mind says:

1. stop jamming them, go to .020 jump and test, see what you get. I never jam unless I absolutely have to, it's nothing but problems. Betcha your primer pockets stop loosening up if you go to a short jump from the jam and I'll bet your sooting issue moves to the necks from the shoulder.
2. Sooting to me suggests that the necks aren't expanding quick enough to seal the chamber so might want to anneal every time too.

I spent first few hundred rounds (I see you cringing, and I understand) playing with jump, mostly .015 but also a few of the "Berger" seating length tests with lots of jump. Jam is only on very recent tests, and is shooting substantially better than jump right now.

 

[Lone Hunter]

Try a different powder. As has been said about H4895 it has a lot of variance between lots. I use it in my .308 and it performs well. Try Varget or something close to it's burn rate. I tried H4895 in my 6BR but the accuracy just wasn't there. Varget, IMR4064 , SW Precision, and IMR 8208 did well. Good luck and hope you figure it out.

 

[Webster]

You caught my math error and I do get .268/.2685 loaded diameter (standard micrometer) and .0120/.0125 per side (tubing micrometer with a pin anvil). I measure .2433 at the pressure ring.

Barrel is 26" long, .236 / 5R. Shoulder bump is set by bolt close with no resistance plus .0015". I have no idea how many "turns" the die is set to but I have the lock ring set to produce that comparator length consistently.

I suppose the mystery still boils down to why the neck isn't sealing, and what I can do about it as I'm now planning to back down charges further. Mike E Glantz is suggesting more aggressive annealing and leaving a bit of unsize neck length.


I spent first few hundred rounds (I see you cringing, and I understand) playing with jump, mostly .015 but also a few of the "Berger" seating length tests with lots of jump. Jam is only on very recent tests, and is shooting substantially better than jump right now.

I don't know if neck sealing is a real problem or imaginary. I have had it for years on many cases without any problem that I know of. My guess is it leaks a little then seals. It does not allow erosion in the chamber.

 

[dgeesaman]

Try a different powder. As has been said about H4895 it has a lot of variance between lots. I use it in my .308 and it performs well. Try Varget or something close to it's burn rate. I tried H4895 in my 6BR but the accuracy just wasn't there. Varget, IMR4064 , SW Precision, and IMR 8208 did well. Good luck and hope you figure it out.

I've tried H4895 (have an 8 pounder), AR-Comp, XBR8208, and Reloder 15. None were clear winners with what I'm doing. It stings a bit to consider I have 7 lb of H4895 that might be useless. I'd at least like to get a useful load from the H4895, even if it's slow.

 

[mikecr]

How far have you trimmed from chamber end (end clearance)?

 

[searcher]

Simply jamming bullets as you did will not likely be the source of the soot problem. Only time I ever had soot was with underpowered loads. Using powder that does not fill the case adds to the problem, creating "pre-detonation". Sometimes, you can tell that is what it is simply because of a detectable delay in trigger snap and bang.

 

[JMayo]

My old 6bra barrel started getting the same rings on the shoulder.
I contributed it to case hardening and a worn neck/shoulder junction in the barrel. It was not jammed, it was a very worn barrel.
I changed barrels about that time.
The new reemer used is very exact for neck/shoulder.
This doesn't help anything I know. But it's interesting I had the exact experience on the weird, not precise ring on the shoulder.

 

[Dusty Stevens]

Dont waste your life on a schitty barrel. If its pressuring up at that velocity, replace it

 

[dgeesaman]

How far have you trimmed from chamber end (end clearance)?

I don't know how to measure it but I can see a gap with my borescope and a piece of fired brass.

Dont waste your life on a schitty barrel. If its pressuring up at that velocity, replace it

Noted. I have my concerns that my cleaning could be better and I'm going to give it a serious cleaning before I send it off to be re-barreled.

The fact you're using a bushing die, you cant size the entire neck anyways. I'm only sizing about .180" or so of the case. Just enough to hold the pressure ring.

In fact, with my Whidden die set with the bushing just barely free to move, I was sizing the entire neck. Or nearly all of it.

I tried backing it out a couple of turns so that it sized about 2/3 of the neck length. It sealed up much better.

David

 

[mikeeg02]

Good to hear. I'd also try that annealing setting like we talked about. The barrel I shot at gba with newer cases and the same bullets and powder gave false pressure signs early like yours did. I shot a test yesterday and went up to 3020 with the same bullets and powder without issue. I wouldn't get excited about it being a bad barrel.

 

[JMayo]

If you raised die dro to not size neck as much then you didn't set shoulder back as far ?

Setting shoulder back too much could be the deal.

 

[mikeeg02]

If you raised die dro to not size neck as much then you didn't set shoulder back as far ?

Setting shoulder back too much could be the deal.

You can adjust the bushing depth down the neck separate from shoulder bump on a bushing die

 

[mikecr]

The advantage here(bushing use) being that you DO NOT FL size necks, and can adjust tension with chosen length of neck sizing.

 

[dgeesaman]

You can adjust the bushing depth down the neck separate from shoulder bump on a bushing die

That is what I did: I backed the bushing away about .06” without changing the shoulder bump.

I will anneal more aggressively this time around.

On the pre-Aztec annealing codes: do they vary with the strain hardened state (number of firings since last anneal)?

 

[mikeeg02]

That is what I did: I backed the bushing away about .06” without changing the shoulder bump.

I will anneal more aggressively this time around.

On the pre-Aztec annealing codes: do they vary with the strain hardened state (number of firings since last anneal)?

I anneal every time at the setting we talked about, which is more aggressive than most, and looked to be a little more aggressive than aztec mode from what I could see in the picture. You will have to test on your own how many firings you can get, and achieve the results you want before re-annealing is needed again.

EDIT: I may have misunderstood your question,

If you meant the difference between the case having 1 or 10 firings on it since last anneal and using that value; In my testing the ones with several firings would require a higher number to achieve the same results as one with only 1 firing since last anneal.

 

[JMayo]

Ahh, mine is screwed down tight. Didn't realise to let it be lose would allow bushing to ride up = less neck resized.
Another learning curve established !

 

[mikeeg02]

Ahh, mine is screwed down tight. Didn't realise to let it be lose would allow bushing to ride up = less neck resized.
Another learning curve established !

I would suggest backing the jam off just a smidge at the minimum, allowing the bushing to "free float". Because of tolerances, the bushing can move from side to side slightly, and allowing it to free float helps keeps things centered, whereas a bushing locked down can induce issues, such as runout in the neck.

 

[JMayo]

I would suggest backing the jam off just a smidge at the minimum, allowing the bushing to "free float". Because of tolerances, the bushing can move from side to side slightly, and allowing it to free float helps keeps things centered, whereas a bushing locked down can induce issues, such as runout in the neck.

The bushing its self floats inside the die.
Loosening the screw on top where the bushing is put in allows it to rise even more ? I assumed this is what you were saying.

 

[mikeeg02]

The bushing its self floats inside the die.
Loosening the screw on top where the bushing is put in allows it to rise even more ? I assumed this is what you were saying.

Correct if I am understanding you. Previously you said screwed down tight, which made me thing tight as in jammed tight.

Ahh, mine is screwed down tight.

 

[Dusty Stevens]

Back off on the bushing til you can hear it move when you shake it