There have been a variety of threads over the last 10 years about using 9mm brass to make .308 jackets. Most have been notional discussions; others have been the actual production of a set of dies and testing. Three of these can be found at the following links:
http://castboolits.gunloads.com/show...from-9mm-brass
http://castboolits.gunloads.com/show...to-308-jackets
http://castboolits.gunloads.com/show...-rifle-jackets
My wife wanted to know what I wanted for last Christmas; and Dave Corbin had a sale going on, so I ordered a set of .308 RBT Swage dies, and also his 9mm brass to .308 jacket dies. Last week I got a ROUND-TUIT and pulled out the 9mm to .308 die set. Sorted through a 5 gallon bucket of 9mm brass and picked out over a hundred “Blazer” 9mm Brass cases to use as donors for making .308 jackets. I annealed all of these 9mm cases by holding them in a 1lb propane burner flame, with the point of a 16d nail in the brass, and used a set of pliers to hold the nail until each case was a Bright Orange – then dropped it into a water pan to cool.
The Dave Corbin 9mm to .308 die set uses a tapered/rounded punch with a small tip on the end as a punch (the tip just sits in the flash hole, and the case totters on the tip) to push the 9mm case through the die. The tip on the end of the punch is used to support/center the brass case as it is pushed up and into the sizing die (Single die where several others have used multiple dies to size down in incremental steps) as it is reduced to .308 jacket size. Primers are removed before sizing (I removed them before annealing).
I initially sized about 15 cases to make .308 jackets just to explore the dies. Followed by swaging cores into the jackets, formed RBT bases, and pointed them up. Almost all of these had bases that were lopsided (one side longer than the other).
This morning I swaged an additional 20 jackets and about 1/3 had bases with one side severely elongated, 1/3 with minor elongation, and 1/3 that were flat or almost flat at the base. Careful attention to setting the 9mm onto the punch and steering it into the mouth of the die produces fewer dramatic “Cull’s”; but I am not confident that the bases are going to be acceptably “Flat” on the bases. I am not shooting any of these as I feel they will probably be poor performers and a waste of powder and primers with the current production results.
My current thoughts are that I may try using a Lee .357 (or .358) sizing die as an intermediate sizing operation. Thinking is that perhaps I can get a “Straight Entry” of the 9mm case into the Lee .357 sizing die (not skewed off line); then a run through the Dave Corbin 9mm to .308 die set. The Lee punch is flat so it may be that I can align the 9mm case more concentric to the sizing die. My speculation is that with the Dave Corbin die set, any blemish on the flash hole of the 9mm case is causing an off center entry into the sizing die. I do not fault the Corbin die set; after all Dave Corbin in his literature specifically calls out that the set will not produce “Match Jackets”; rather it is intended for making short range plinking/hunting/survival bullets.
Although there are differences in the dies and techniques; we do see dies available to reduce commercial .30 jackets to .285, 7 mm, etc.. Why can this be successful, yet reducing a 9mm to .308 is highly problematic.
Anyone getting “Fair” to “Good” accuracy out of .308 bullets made from 9mm to .308 Jackets? BTSniper seems to have settled on the 5.7 x 28 case for making jackets; but they are more difficult to come by compared to 9mm cases being everywhere on many ranges. May try some of the “Best” jacket bases to make up some .308 Winchester rounds and see if they can be kept on the paper.
It would really be nice if we as a community could improve this to the point where 147/150 grain .308/7.62x51 rounds for use in M1A (m14’s) were feasible with, accuracy rivaling milspec ball being achieved from home made swaged bullets. After all, tremendous improvements have been made in cast boolits, PC’d Boolits, and home Swaged bullets.
For Discussion in this Thread:
What ideas are out there on improving the base of jackets produced from 9mm brass?
How about ideas on how to “Iron Out” the off center/skewed jacket bases?
Anyone getting “Fair” to “Good” accuracy from incremental sizing (Multiple dies) of 9mm brass to .308 jackets?