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hwingo
01-05-2010, 08:46 AM
Hi David (and others),

I rarely participate in this part of the forum but on occasions I have a few questions that need answers.

You and I (as well as Reid) have talked on more than just several occasions in the early 80's when you worked at Brownells. I was quite active in the 80's building Bench Rest rifles. I valued your opinion at that time; nothing has changed as you still have my ear.

Regarding "birth" of the PPC and its celebration for accuracy, there seemed to be several attributes of the parent case that significantly contributed to the success of the PPC. For starters, the 220 Russian had a small primer pocket when compared to the AK round. More than several tried using the 7.62 X 39 case when 220 Russian brass began to disappear. The AK parent case didn't do so well. Many were of the opinion that the small primer pocket was one of the contributing factors to the success of the PPC.

No less was the fact that Ferris and Lou changed the shoulder angle from 16 degrees to 33 degrees and I *think* the wall of the case, when fire-formed, had less of a taper (straighter walls) all of which increased internal capacity of the case.

Aside from the fact that internal capacity increased, some were of the opinion (e.g. Boyer, Fowler, et al) that shoulder angle, in and of itself, contributed significantly to accuracy. I would like to hear your view on this matter.

I have been playing with the idea of building a 416 using the 50 BMG as the parent case. Length of the case would not change (as it did with Barrett's). Rather than shortening the case, I was considering changing the shoulder angle from 16 deg to 33 deg and possibly giving the case a wee more straighter wall. Using a bullet with a high BC and a twist rate of 1:12, I was hoping for a faster .... more accurate round with changes as mentioned above. Do you think that these changes would improve accuracy as it did with the PPC?

Harold

38_Cal
01-05-2010, 09:30 PM
Hey, Harold. Long time since we spoke last. I've been gone from the B Co. for over two years now...not by my choice!

I'm really not the best guy to discuss internal ballistics with. Gun building, stock making, repairs, cast bullets, Schuetzen shooting, traditional muzzleloading, yep. Case design...not much to go on in my background, but your idea sounds reasonable. One thought, though. Have you sectioned any .50 BMG cases, to see what you would be up against in blowing out the shoulder? I know that the neck wall thickness is somewhere around .025" per side, and I would guess that the shoulder/body is correspondingly thicker as well. You may want to see about building a tool to hydraulically "pre-expand" the shoulder area after necking the brass down, might be easier on the cases.

Best of luck on the project. Keep us informed!

David