PDA

View Full Version : What are ARs max chamber pressure limit before kaboom?


mecam
04-30-2008, 8:31 PM
What are ARs max chamber pressure limit before kaboom?

762cavalier
04-30-2008, 8:49 PM
don't know about max but I think the AR is SAAMI rated at 50,000psi anything past that is in kaboom territory.

Ech0Sierra
04-30-2008, 8:49 PM
What range are you going to to test these loads? I'm scared to go now... I don't want aluminum chips in my body.

CSACANNONEER
04-30-2008, 8:57 PM
I guess it depends on what your upper is chambered for. I've got .22lr to 50BMG uppers. Are you talking .223, 5.56, 6.8, .458 socom, 9mm or?

MILLITIAof1
04-30-2008, 9:01 PM
I guess it depends on what your upper is chambered for. I've got .22lr to 50BMG uppers. Are you talking .223, 5.56, 6.8, .458 socom, 9mm or?

I think he is talking about 30mm:eek:

mecam
04-30-2008, 9:06 PM
This for a .223. I'm trying to accomplish 2900fps on 16" barrel with a 55gr. Based on my calculation with a varget powder, the pressure would be very near 50,000psi, I think. :shrug:

CSACANNONEER
04-30-2008, 9:11 PM
Is the barrel marked .223 or 5.56? There is a little difference in max pressure between the two.

mecam
04-30-2008, 9:13 PM
Is the barrel marked .223 or 5.56? There is a little difference in max pressure between the two.

It's marked 5.56. So is there some pressure relief there?

ar15barrels
04-30-2008, 10:11 PM
Military test acceptance is a 70,000PSI black pill load and THEN they inspect for cracks in the bolt and barrel.

http://ar15barrels.com/tech/hpt-specs.jpg

The USA spec is 55,000 PSI with an allowance above that for temperature effects.
Some of the European 5.56 ammo is loaded to near 62,000 PSI.

I generally recommend keeping 5.56 ammo at or under 60,000 PSI and 223 ammo at or under 55,000 PSI.

Kabooms are probably happening in excess of 100,000 PSI.

mecam
05-01-2008, 6:07 AM
Thanks Randall. Now I just gotta make sure I use only once fired brass if I'm gonna do hot loads. :)

Fjold
05-01-2008, 6:09 AM
Is the barrel marked .223 or 5.56? There is a little difference in max pressure between the two.

There is a difference in the cartridge max pressure but there is no difference in the upper assembly strength.

ar15barrels
05-01-2008, 6:12 PM
There is a difference in the cartridge max pressure but there is no difference in the upper assembly strength.

The larger/longer throat helps lower pressure too.