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470 - I am very much aware of the difference in pressure generated between the old, virtually obsolete DR rounds and the more modern bolt action rounds. Have been since 1968 when I started loading and making a study of rifle and ctg. ballistics.

My point was the .500/416 is a low pressure round designed for the old school DR shooter - and as such, it is surprising it didn't become more popular than it has - amongst the low pressure DR crowd, that is. Seems to me, that's pretty much what my first post said initially.

High pressure rounds rare in a DR? - yes, I guess, but still there somtimes - seems to me I've seen Rigby's or maybe W.Richards DR's for sale, chambered for the .375H&H (not the low pressure flanged version). Now, the .375H&H a 60,000psi range ctg. with a .532" rim and the .458 Win Mag. same rim diameter, but lower pressure, but still a firm 55,000psi round, I think.

I wonder about a cordite round that produced 40,000
psi 'at home' then fired in rifle which was originally regulated in Merry old damp England, but after being carried in "the front of a shirt pocket" or ctg. loop was then thrust into a blued/blacked rifle that had been carried in the 120F heat under a blazing sun, barrels so hot they couldn't be touched, let alone held.

How much pressure did that cordite loaded round produce?

Did anything happen to the regulation, so painstakenly adjusted for bullet weight, pressure, velocity and recoil at 60F - maybe 70F or perhaps 55F or even colder - what time of year were the barrels regulated? - how did that round so carefully regulated shoot, after being bounced up in pressure an incredible amount by the heat of the sun and sitting in the tubes (or even freshout of the pocket - almost instantly taking on the temp of the tubes) - how did it shoot, accuracy wise?

Care to guess how much pressure those guns are actually handling or have handled, shot after shot?

We all know why those old ctgs. were loaded a low a pressure. It was because of African heat & cordite.

What about using modern powders that are not heat sensitive at all - or at least very much less senstive.

Thus, the .375H&H and .458's become viable DR ctgs. as they did or have.

Incidently, the Hodgdon Extreme (ADI) powders, perhaps the least heat/cold sensitive that are avilable, are fairly recent additions to those available, yet the .375H&H and .458 mags pre-date those 'best' powders. This says modern DR's can be chambered easily for more efficient rounds, that develope slightly better ballistics than the old ones - is all- which of course, has nothing to do with this thread.

edited to correct this spelling mistake:(not the low pressure flanged version).

Edited by Daryl_S (11/04/11 01:59 AM)

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