Cosmoline: Body taper the same, just move the shoulder forward about 0.100 inches, and maybe increase the shoulder angle to about 30 degrees. Actually, looking at the drawing, I guess moving the shoulder forward 0.086" would be about right, and changing the dimension (1.56 39.62) to (1.646 41.81). Smaller shoulder, but you're not headspacing on the shoulder, so who cares?
W.E.G.
What, the recoil isn't already enough for you?
Recoil, schmecoil. Having never fired a Mosin Nagant, I can't imagine the recoil
in the rifle with the military load being worse than a Springfield. I'm wondering if all the tales about recoil and muzzle blast and flash aren't with respect to the carbine only. However, once again, I have never fired either a Mosin Nagant rifle
or carbine. Of course, there will be more recoil in any "Improved" M-N round, but how bad can it be? In the
rifle, I emphasize.
Cracked Butt:
Doing an AI treatment means more case capacity so that you can use more powder without raising pressures.
Thank you for pointing that out. I rather thought that was common knowledge. (I presume by "AI" you mean "Ackley Improved?"
It should work, but the only question is why bother?
I don't understand the question... Oh, wait a minute... I guess for the Sake of Pure Science and for Improving the Health, Benefit and Welfare of the People of the State of Colorado.
And for the same reason people stroke and bore big block Chevy 454 CID engines. Actually, as I mentioned, it would be so that while you could fire standard factory loads in it (with somewhat reduced velocities), you could use the Improved version for long range sheep shootin' and big (big) game.
rcmodel: Roy Weatherby used to be called the High Priest of High Velocity, and that's all he was going for. Numbers.
And,
But after folks started using strain guages on them it was learned that they were off the charts pressure-wise in order to get those eye-opening velocities!
Yes, if you wanted to "marketeer" your particular Improved cartridge, you'd cram as much powder in as you could and let fly. But I point out that a lot of Palma Match loads overfilled the case and you had to dribble the powder in slowly so it would settle right and take up less volume. And many Palma loads had another primer sitting on top of all this powder to enhance ignition.
I suppose so many designers of the Improved cartridges went wrong there. They weren't either paying attention to or didn't care about the
peak pressures. Bear in mind that, given the same rifle and primers, a common practice was to watch for excessive "Primer Units of Pressure" when working up loads. A cratered primer was well beyond the point at which you should've quit adding more powduh. If enough is good, more is superber.
And you (rcmodel) added, quite appropriately,
Some of the newer powder available now is quite dense, and a lot of it would fit in a standard case.
When I was loading extensively, IMR 4350 was about the slowest canister powder (meaning stuff you could buy over the counter) available.
Cosmoline's and JesseL's points should be noted here... If you can lengthen out the pressure drop-off as the bullet goes down the bore, you
do get higher velocities without increasing the
peak pressure, especially if you use slow powder and a longer barrel.
And the barrel on the M-N is a whole
twenty-six and one half inches long.
The point I was trying to make was that on eyeballing that long neck on the M-N case, it looked like it would be a good Improved cartridge for long range shooting, and wondered if anyone had tried it.
I would have liked to have heard from some of our Norwegian, Swedish, and Finnish members on this matter of building a 7.62 X 54R Improved cartridge, since apparently, according to the link in Post 2, they've done a lot of 'sperimenting with that cartridge.
