Gas marks on shoulder?

[wapiti6x6]

I've noticed this only recently. New brass that has been full lengthed, once, twice fired etc. All brass is being FL'd after firing and shows gas on shoulders part of the time, one's with no gas marks have different POI than one's showing gas on shoulder. I have backed my die off to keep from bumping shoulder and the problem is still there. The rifle: over the counter REM 700 in 7 rem mag. Brass: WIN Die: RCBS Bullet: 150g NOS PAR/ 160g ACC Bond Charge: 69.5g retumbo or 63g h4831 w/ NOS PAR and 67-68.5g retumbo with 160g accubond. Seating depths vary. No chrony to check speed. I know this has been posted before but it seems there is more to this. Any suggestions would be great. Thanks in advance, great board here, been viewing for a year or more and finally decided to ask some of the finest about my problem.

 

[rotorhead]

Try neck sizing your brass/ what kind of brass are you using?

 

[308sako]

I note that you are using Winchester brass which is quite good normally. Does this happen with factory virgin brass in reloads? If not, I would be inclined to think that the problem is in the sizing die, and do recomend trying to just neck size a few cases. I would add that if the brass neck thickness is under sized for the chamber that the relatively slow powders which you are using may not be sealing the case agaisnt the chamber as well as you might like. Hence the low by evidence. I use R22 with the 160 AB and love the results in a Ruger 77-2 SS. Good luck.

 

[wapiti6x6]

This is my first lot of Win brass and it started showing up with the first firing. The brass was FL sized and fired, normally I fire at least twice before I get too serious. After two and three the gas marks are still randomly showing. I haven't tried necking only. I have tried RL-22 with decent results but loads were seemingly slow, 61-62 grains. Would light charges cause the same scenario as slow powders? The Rem and FED brass doesn't seem to have any problems.

 

[Wild_Bill]

Hi the Win brass has more capacity than some other cases i would increase the loads slowly and i would bet that that will fix the problem. The problem usualy occours when the pressure inside the case is not enough to seal the case neck to the chamber wall. The WSSM cases are remoned for this as their necks are very thick. I have seen this with cases from 222 up to 375H&H. some cases end up with large dents in them around the neck junction when the gas comes back and colapses the shoulder.

Cheers Bill
Australia

 

[rotorhead]

I'm courious, What kind of dies are you using? What rifle are you using?

 

[Hired Gun]

From the original post.
[ QUOTE ]
The rifle: over the counter REM 700 in 7 rem mag. Brass: WIN Die: RCBS

[/ QUOTE ]

 

[Centre Punch]

Hi, I'm with wild bill on this one, i presume by gas marks you mean black deposits.
My buddy had the same problem with his 6.5 swede, as he increased the powder charge it disappeared.

Ian.

 

[wapiti6x6]

Thanks everyone for the input, I've gone back to Rem brass and haven't had any gas marks (black soot) on the shoulder. Also tried slightly hotter loads with the Win brass and accuracy fell off badly with the gas marks still showing up.

 

[Wild_Bill]

Hi yes with the black marks on the neck. Another thing you could do if you want to use up the Win Brass is anneal the cases it may not be worth it to you som eof the Win cases also have hard brass and if you anneal it it will seal at a lower pressure but like you i use Rem Brass over Win where i can.

Cheers Bill
Australia

 

[dbhostler]

You can also increase neck tension and/or seat the bullet deeper as well as add more powder or even use a hotter primer. /ubbthreads/images/graemlins/grin.gif
db