.30/338 Project

gablues · December 6, 2006, 04:42 PM

I am very new to this and just had some questions. To build a .30/338 rifle what caliber would I need to have the barrel chambered for? What action should I use (Considering Winchester Model 70) and what Barrel/barrel length? Told you I was new. Thanks.

Harry Bonar · December 6, 2006, 05:18 PM

Sir:
That would be the 338 Win Mag. case necked DOWN to 30 (308). There are dies made for this and are sold by most die mfgrs.
It is an overbore cartridge, not very efficient, and drives heavy bullets very far, very fast to quote one manual, the 300 win mag gives velocities virtually identical to this.
Any modern long action will be fine on strength. We must understand that virtually all high intensity cartridges operate at the same pressures (In the 54,000 cup. range) PSI is very different - don't try to extrapolate psi into cup!
Brass starts to flow at about 70,000 cup. Rifle bbls and actions (modern) now, even the Mausers off WWII vintage were designed to handle almost twice these pressures - the case is the weak link.
Headspace, and head-thrust are important considerations as well as chamber finish and case design.
Even large anti-ordinance rounds, tank rounds run at approximately these pressures.
Harry B. Some of these wildcats are much trouble and no better than are our factory cartridges ( they were once wilcats themselves).

December 6, 2006, 04:42 PM	#1
gablues Junior Member Join Date: October 5, 2006 Posts: 4	.30/338 Project I am very new to this and just had some questions. To build a .30/338 rifle what caliber would I need to have the barrel chambered for? What action should I use (Considering Winchester Model 70) and what Barrel/barrel length? Told you I was new. Thanks.

December 6, 2006, 05:18 PM	#2
Harry Bonar Senior Member Join Date: December 5, 2004 Location: In the Vincent, Ohio general area. Posts: 1,804	30-338 Sir: That would be the 338 Win Mag. case necked DOWN to 30 (308). There are dies made for this and are sold by most die mfgrs. It is an overbore cartridge, not very efficient, and drives heavy bullets very far, very fast to quote one manual, the 300 win mag gives velocities virtually identical to this. Any modern long action will be fine on strength. We must understand that virtually all high intensity cartridges operate at the same pressures (In the 54,000 cup. range) PSI is very different - don't try to extrapolate psi into cup! Brass starts to flow at about 70,000 cup. Rifle bbls and actions (modern) now, even the Mausers off WWII vintage were designed to handle almost twice these pressures - the case is the weak link. Headspace, and head-thrust are important considerations as well as chamber finish and case design. Even large anti-ordinance rounds, tank rounds run at approximately these pressures. Harry B. Some of these wildcats are much trouble and no better than are our factory cartridges ( they were once wilcats themselves). Last edited by Harry Bonar; December 6, 2006 at 05:26 PM. Reason: spelling and info addition.