Re-seating bullets and chamber pressure

blue 7 · June 6, 2008, 09:34 AM

I am a new poster here, however I have been reading the post for several months.
My question is chamber pressures in re-seating some ammunition (Wolf) will not feed properly from the magazine in my AR-16. The first round or two will feed and extract however the remaining rounds will not feed.
I measured the C.O.A.L against ammunition that would feed properly and the Wolf ammunition was slightly longer. I also observed the Wolf seemed to be hanging up in the forward part of the magazine. Several different makes of magazine were tried with the same results, hang ups and failure to feed.
Is there any chamber pressure problems in re-seating the bullet a few thousands of an inch.
Thanks in advance for any and all advice.

blue 7

SL1 · June 6, 2008, 11:13 AM

If you are talking aobut RIFLE rounds, such as the .223 or .308, then seating the bullets a few thousandths deeper should not cause any pressure problems, probably even a slight decrease.

BUT, if talking about SHORT, SMALL-CASED rounds like 9mm or 40 S&W (in carbines or pistols) seeting deeper CAN make a much larger pressure difference, and it would be an INCREASE. For example, on page 349 of Speer manual #10, there is a warning in the 9mm section:

Quote:

... loads that produced 28,000 CUP went to 62,000 CUP when bullets were purposely seated 0.030" deeper!"

That was probably the worst-case powder and bullet combination that they ever found, but it should serve as a warning not to do it until you have figured-out what the effects will be in YOUR case.

SL1

ryalred · June 7, 2008, 10:09 AM

I doubt it will make a significant difference in the pressure. To be sure, you could seat them to the new dept in steps--very little at a time and shoot them and look for pressure signs.

totalloser · June 10, 2008, 02:53 PM

I would say that in certain circumstances this could be dangerous. But the main issue to consider is the possibility of a compressed load. Most commercial ammo uses finer powders for economic reasons, so the powder has more airspace. The pressure really climbs when the bullet compresses the powder. This is to be avoided. If you push the bullet back, and you can shake it and still hear the powder shaking around, it is obvious you don't have a compressed load. I can't say it won't raise the pressure, but in my OPINION, the pressure will not raise significantly as long as you still hear/feel the powder moving around.

June 7, 2008, 10:09 AM	#3
ryalred Senior Member Join Date: March 24, 2008 Location: SE Oklahoma Posts: 491	I doubt it will make a significant difference in the pressure. To be sure, you could seat them to the new dept in steps--very little at a time and shoot them and look for pressure signs. __________________ ryalred rifle & muzzleloader -- exhilarating bowhunting -- obsession reloading -- addicted

June 6, 2008, 09:34 AM	#1
blue 7 Junior Member Join Date: June 6, 2008 Location: half way between DEN and SLC Posts: 4	Re-seating bullets and chamber pressure I am a new poster here, however I have been reading the post for several months. My question is chamber pressures in re-seating some ammunition (Wolf) will not feed properly from the magazine in my AR-16. The first round or two will feed and extract however the remaining rounds will not feed. I measured the C.O.A.L against ammunition that would feed properly and the Wolf ammunition was slightly longer. I also observed the Wolf seemed to be hanging up in the forward part of the magazine. Several different makes of magazine were tried with the same results, hang ups and failure to feed. Is there any chamber pressure problems in re-seating the bullet a few thousands of an inch. Thanks in advance for any and all advice. blue 7

June 10, 2008, 02:53 PM	#4
totalloser Senior Member Join Date: October 19, 2007 Location: Fort Bragg, CA Posts: 679	I would say that in certain circumstances this could be dangerous. But the main issue to consider is the possibility of a compressed load. Most commercial ammo uses finer powders for economic reasons, so the powder has more airspace. The pressure really climbs when the bullet compresses the powder. This is to be avoided. If you push the bullet back, and you can shake it and still hear the powder shaking around, it is obvious you don't have a compressed load. I can't say it won't raise the pressure, but in my OPINION, the pressure will not raise significantly as long as you still hear/feel the powder moving around.