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Terry Wieland in his book "Dangerous Game Rifles" points at the big difference between
the pronounced body taper of the original 375HH and almost parallel sides of the improved
version. The resulting increased case capacity he says allows higher velocity, but brings the danger of case-sticking because of higher pressures and almost parallel sides.
I think he has a point there.
Greetings,
Livinus

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: Improved cases extract effortlessly at pressure levels that would freeze the same action when shot with the tapered case chamber. This is due to the straighter sided cases reducing bolt thrust. I've been shooting improved cases for over 35 years so have some meager experience with them. In all ctgs. and case sizes, the improved designs extract without trouble from strong bolt actions.
: For a tapered case to stick in a bolt gun, one must be loading at too high a pressure for that gun and chambering.
: Many barrels can run higher pressures with published loads, than given by the test barrel. This is why one ALWAYS starts low and 'developes' one's own data for his/her paticular rifle.
: I have never had cases stick in an improved chamber, from the .17AH to the .375 Weatherby, nor have I ever had hard bolt lift with any of them. However, get pressures a bit too high with a tapered case and the bolt will get sticky.
: For expample, my .375/06IMP runs 2,845fps with 235gr. Speers and 2,875fps, same load, with 220 Hornady Spire points. Both are long range deer loads. For thumping bigger game the same rifle runs 2,675fps with 270's and 2,470fps with 300's. Cases have been loaded over 10 times with the same loads with primer pockets still factory tight. There has never been a bolt lift stickiness and I stopped load development merely due to having established safe maximums for that rifle giving all the performance needed for any game, anywhere. When my .257 AckIMP Roberts matched a friend's .257 Wheatherby wiht factory ammo, I stopped it's load development. One cannot argue with .999", 5 shot groups at 200 meters and 25 to 35 rounds per case in longevity. Good enough for a light #3 barrel, I think.
: Point is, Improved cases give less extraction problems in bolt guns than tapered ones. The 3,485fps loads from the .257 dropped from the chamber when the extractor was removed for a test.
: I would estimate these loads were on the hairy side of 65,000PSI, yet didn't expand the primer pockets or case any 'feel' in the bolt. Good brass is manditory. Some is softer than others and causes problems with top-end loads.
: Properly loaded brass shrinks .001" from the chamber walls, which results in perfect extraction, every time. If it doens't, you've exceeded the brass's elasticity point due to pressure that's too high for THAT brass.
: If one wants slightly greater ballistics than the .375H&H provides, then buy or chamber up a .375 Ruger.
: The standard .375 has all the power necessary and then some. It need not be loaded 'to the nuts' to take care of all game. One need only be a moderately good 'game' shot. Another 150fps won't kill game any faster or deader with the same hit. It is merely more difficult to shoot due to greater recoil.
: It's been said before and will be said again. The .375H&H gained it's reputation or being satisfactory for all African game with velocities 100fps to 150fps LOWER than current factory ammo and 200fps to 250fps lower than what one can handload that round today with modern powders. Need more? I hardly think so.
: Sorry if this offends anyone - you are too easily offended - get over it, in my MOST humble opinion, of course.

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Daryl


"a gun without hammers is like a Spaniel without ears" King George V

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