Dual purpose 338

[mtang45]

I have been noodling the possibilty of building a rifle with a 16 inch barrel, that has both good subsonic and good supersonic performance out of the same cartridge; but different loads. I think I have finally narrowed down the choices to a 338 Federal. I can get decent full power performance out for several hundred yards and also good subsonic performance with bulky pistol powders, for quiet close range stuff. It also has the benefit of commercial loadings and an easy neck up of a .308.

My only remaining question before launching this project is that at subsonic speeds the 300gr pills pretty much require a 7 twist barrel to stabilize it. Is this twist too fast for the full power 300gr bullets?

 

[bohem]

Re: Dual purpose 338

Nope, you'll be OK there with that case capacity.

 

[mtang45]

Re: Dual purpose 338

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bohem</div><div class="ubbcode-body">Nope, you'll be OK there with that case capacity. </div></div>

Thanks bohem. So the velocity out of the 338 Federal is not fast enough to be concerned?

 

[bohem]

Re: Dual purpose 338

Nope, not enough "oomph" to make those 300SMK's come apart.

There are guys shooting 9tw 338SnipeTac chambers with 300 SMK's over 3300fps and the bullets stay together. I'd be surprised if you can get the 250 SMK's over 2500fps, let alone the 300s at 2500fps.

Checking the exit RPM's you get

Snipetac:
3300*720/9 = 264 krpm


338 Federal
250's @ 2500 2500*720/7 = 257.1 krpm
300's @ 2400 2400*720/7 = 246.9 krpm