23 January 2004, 04:12
Nishoba01Re: .408 Cheyenne Tactical
Thanks for your help guy's
23 January 2004, 14:25
ScottSWhat barrel length are you using? 2810 fps with a 400 gr VLD would generate ~ 60000 psi chamber pressures, according to my calculations, with a 27 in barrel. I admit that is only a educated guess, but I share you doubt at achieving 3000 fps, unless you have a long barrel.
Scott
23 January 2004, 14:57
Bwana-beI don't think it unreasonable for this sort of cartridge to be chambered in a 30" bbl. Given that, it seems easy to expect 3k. I beieve that 419g bullet is 2.2" long (BT=.28"x.35", 9 sec ogive, BC.940!), and the COL is around 5". Powley says 2950 fps <50k CUP with a 30".
If that BC is right, it's lost about 900 fps, where it doesn't even have a measely 4k ft lb ME.
24 January 2004, 06:21
ScottSBwana be,
Not starting a fight, but 50,000 CUP in a 505 Gibbs based cartridge necked down to .416 is well over 60,000 PSI and is closer to 70,000 psi.
I believe the reason that the web was so strongly reinforced in the 408 Chey Tac case was to allow for chamber pressures in the 70,000 psi range. The Gibbs,like the Rigby and 500 Jeffery, are good to around 60,000 psi. Above that the web begins to bulge and you will notice extractor marks and/or hard extraction in a Mauser actioned rifle.
Scott
24 January 2004, 08:27
GeorgeInNePaBefore you buy, go to
LongRangeHunting.com and ask there. There are guys who shoot this round in custom guns, and guys who have given up on the .408 altogether.
The CheyTac case is NOT just the .505 Gibbs. It has a thicker head and web.