Primers and Pressure

[JRLSH]

Hello all, and thanks for all the help in the past but I have a new problem however with some rounds I recently loaded. I had some pre primed brass that I reloaded with powder and bullets and some factory rounds. Shot them and the pics show the primers. #1 was the factory round and it looks to me like this one is normal. #2 was one of the reloaded rounds. Primer looks like it has flattened out somewhat. #3 was one of the reloaded rounds and looks worse than #2. Both the reloaded rounds were identical in powder charge, bullet weight, trim to length, seating depth, headspace was -.001, rounds chambered same as factory. I had load data for WC860 powder but the load was on the low end of the scale(minimum load). I've read that when pressures are high and the primers flatten out it could be that not enough powder was used but I am leary of using more powder to prove that the flattening of the primers was caused by loading on the light side of the starting load data. Any suggestions on bumping up the scale of more powder to see if the primers change behavior?

 

[Bart B.]

They all look OK to me. But primer deformation's not all that great in judging peak pressure from. They're not all made to the same metalurgy properties and dimensions so one will deform a lot with a given load and the other not much at all. And a tight bore rifle will cause more primer deformation with a given load than an oversize one.

 

[JRLSH]

Primers/Pressure

Thanks Bart. I have one reloading book that says the same thing, not to put too much stock in reading primers as signs of overpressure and then one reloading book that says to look at your primers as an indication of when overpressurization. Look at this one though and it looks very bad to me...First picture is a primed round, second one is a fired round with same load as the others but the headspace was out just a little more than the OP pics. Could that have made the difference?

 

[Slamfire]

Looks to me that your are shooting 223 ammunition and I am assuming that it is fired in a gas gun.

As Bart has said there are a lot of variables with primers. I have developed loads that gave no indication of high pressures till primers started leaking or were blown. Primers are an unreliable indication of pressure, but they are better than nothing.

 

[steve4102]

What are the details of your load and your rifle?

Picture #3 looks like high pressure to me. Not from the primer, but from the indent in the head at the 9 o'clock position.

WC860 is for the 50 BMG.

 

[JRLSH]

Pressure?

Slamfire/Steve,
The cartridge is .50BMG shot in a bolt gun. The load is WC860 powder, 210 gr. with M33 ball bullet, 650gr. Only variation was the headspace distance between the rounds. Range from -.001 to -.004 on the gauge. All the brass was trimmed to 3.900 and seated at 5.435.

 

[Slamfire]

A 50 BMG is outside of my experience and I have no idea if 50 Caliber primers act the same as small arm primers.

 

[JRLSH]

Thanks Slamfire, I appreciate your help and thank you for your time my shooting brother....