Compressed load and OAL and Pressure


PDA






Afy
June 28, 2008, 03:14 PM
The Sierra Maunal lists 39.5 gr with a 120 gr SMK seated to a COAL of 2.785 inches as a copressed load.

However if I seat to a COAL of 2.91 inches, it is no longer a compressed load. Will pressure go up or down?

If you enjoyed reading about "Compressed load and OAL and Pressure" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!
FieroCDSP
June 28, 2008, 03:16 PM
Any time you increase the OAL on a given charge with the same bullet, your pressure will be lower. If you are using a different (longer) bullet, be careful, as you might seat too deep and spike the pressure.

rcmodel
June 28, 2008, 03:18 PM
It will go down slightly, because of the increased case capacity with the long seated bullets.

Compressing a charge has no effect on pressure one way or the other as long as it is a safe load to begin with.

rcmodel

Afy
June 28, 2008, 03:48 PM
Ok then a follow on...

the 120 GR SMK is 1.179 inches long.. seated at 2.910 COAL means there is only .297 inches actually in the neck/case... which is > caliber .260

What effect would the BT design have on this? Or should I just stop worring and obessing and go shoot the damn rifle already?

rcmodel
June 28, 2008, 03:58 PM
The only sure way to find out what you need to know, as far as load development, powder charge, seating depth, etc, is:

Go shoot the Damn Rifle Already!

You can stew & worry over all the minor details, and none of it does a bit of good until you start testing loads at the range!

rcmodel

Bullet
June 28, 2008, 04:57 PM
While this is not your cartridge it is still interesting , showing how pressure reacts to seating depth, see page 48. I believe this was used by Harold Vaughn. This link takes a minute to open -

http://deepblue.lib.umich.edu/bitstream/2027.42/3866/5/bac6873.0001.001.pdf



.

Afy
June 28, 2008, 05:01 PM
Ok... tomorrow morning I am off to the range to go shoot...

If you enjoyed reading about "Compressed load and OAL and Pressure" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!