416 Rigby Barrel Length

JerryM · July 13, 1999, 01:33 PM

What would the minimum barrel length required to burn 91.5 grains of H 4350 behind a 400 gr Barnes X bullet. I realize this can only be an estimate, but does anyone have a program that might give such info? Thanks. Jerry

bfoster · July 14, 1999, 10:45 PM

I don't have a program which will directly calculate this, but I do have a Oehler M43 and a 416 Rigby, and some experience with working up loads for this calibre. Typically, combustion of single base powders in the range of the H4350 is nearly complete by the time the pressure/time curve is 1/3 to 1/2 way back down from peak pressure. This doesn't mean that you won't have a fireball were you to cut the barrel to 18" as exit pressure & gas temperature is too high not to cause ignition of combustion byproducts upon contact with atmospheric oxygen (this is why there is usually a "pop" from an otherwise very effective silencer when the first round is fired). With this load I'd be reluctant to cut a barrel shorter than 21 to 22".

If you haven't tried IMR 7828 or RL 22, they both produced more consistent results in my rifle. The downside of this is that a 24" barrel is barely long enough.

July 13, 1999, 01:33 PM	#1
JerryM Senior Member Join Date: April 4, 1999 Location: New Mexico Posts: 1,889	What would the minimum barrel length required to burn 91.5 grains of H 4350 behind a 400 gr Barnes X bullet. I realize this can only be an estimate, but does anyone have a program that might give such info? Thanks. Jerry

July 14, 1999, 10:45 PM	#2
bfoster Senior Member Join Date: October 13, 1998 Location: N. of Fords Switch, OK, USA Posts: 297	I don't have a program which will directly calculate this, but I do have a Oehler M43 and a 416 Rigby, and some experience with working up loads for this calibre. Typically, combustion of single base powders in the range of the H4350 is nearly complete by the time the pressure/time curve is 1/3 to 1/2 way back down from peak pressure. This doesn't mean that you won't have a fireball were you to cut the barrel to 18" as exit pressure & gas temperature is too high not to cause ignition of combustion byproducts upon contact with atmospheric oxygen (this is why there is usually a "pop" from an otherwise very effective silencer when the first round is fired). With this load I'd be reluctant to cut a barrel shorter than 21 to 22". If you haven't tried IMR 7828 or RL 22, they both produced more consistent results in my rifle. The downside of this is that a 24" barrel is barely long enough.