From: ian spruce, [EMAIL PROTECTED]
Your question about smokeless loads for the .577/450 Martini Henry
rang a distant bell in my cluttered brain and I recalled an article from
'Handloader Magazine' some time ago. A guy named Jim Jukes wrote a
comprehensive piece detailing a large variety of smokeless powders
suitable for bullet weights from 400 through to 500 gns.
After having dug out the article it seems that most of the Martini
Henry barrels slug out at .456/.457 with a twist of 22" or 33". This
suggests that an unpatched 45/70 bullet would be suitable.
The paper patched bullets made by Kynock until the plant closed in
the sixties measured .472 over the patch and .462 without the patch. The
writer indicates that versatility of the Henry polygonal seven or nine
groove rifling is capable of handling such a wide spread of diameters.
It is also stated as very important to roll TWO sheets of toilet
tissue into a ball and stuff this on top of the charge thus reducing
case space.
A few examples of recommended loads are as follows, with 400gn
bullet 16gns of Unique/Green Dot/Red dot (around 1,100fps). With a 475
gn bullet, 19gns Blue Dot (1,075fps), 22gns Blue Dot (1,220fps). With a
500 gn bullet there appears to be a degree of unreliable ignition
creeping into the test firings with only IMR 3031 (45gns) giving 1,582
fps and IMR 4759 (27gns) giving 1,170fps being the most reliable.
As you must appreciate these figures appeared in an American
Magazine some time ago and as such are for your academic study only. It
is certainly illegal to use nitro in a BP only proofed rifle.
Regards,
Ian
McLean-Spruce
Cybershooters website: http://www.cybershooters.org
List admin: [EMAIL PROTECTED]
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