7.62 X 54R Improved?


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230RN
December 21, 2007, 12:08 PM
Ok, so I've got a mild case of Mosinitis and didn't go in to work today.

So I just bought one of those Mosin Nagants for US$89.95 from Big5 sporting goods and I'm eyeballing the cartridge and I'm lookin' at that loooong neck of about .370 inches and I'm sayin' to myself, "Self, this looks like it's a great candidate for blowing out the shoulder about 0.100 inches and maybe even 'un-tapering' the shoulder."

Sort of like a 7.62 X 54R Improved.

And you could still fire factory ammo in it.

Anyone done this?

Tell you the truth, if I still had my machine shop, I'd be cutting a reamer right now to open up the chamber and try it out.

Anyone? Do I see any hands?

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JesseL
December 21, 2007, 12:43 PM
I asked the very same question a little over a year ago. (http://thehighroad.org/showthread.php?t=218714)

230RN
December 21, 2007, 01:28 PM
Huh. Thanks. Not much info there except the Scandinavians have "probably" done it, but not much is known about it outside of those northern latitudes. I'll check Clymer later.

I surmise, but do not know for sure, that there wouldn't be much need for it for the lack of big game there. Militarily, I don't think there's much need for an "Improved" M-N round, but I'm thinking along the lines of a big (big) game cartridge and long-range high-power target shooting or even long-range sheep hunting.

I've been told that cartridges which headspace on the rim or belt are a little more inherently accurate than shoulder-headspaced cartridges. I can't document this --maybe some gun writer said it long ago because he wished it were so, but it seems reasonable to me.

Hatcher noted that headspace on the .30 Service Cartridge varied quite a bit depending on how fast you closed the bolt on a Springfield. Garands were not so susceptible to this "resizing" of the case since the bolt-lug to the stopping point on the barrel tolerances were much tighter.

And with the fast twist of the M-N (9.5"), it would seem to be well-suited for boat-tailed bullets of around 180 grains or more. And of course, with the M-N, there's that long 26.5" barrel. (Compare with 24" for the Springfield.)

Just skylarkin', I guess, but if I ever get my hands on a lathe again, the first thing I'm going to do is cut a D-reamer for it.

Well, thanks! Not much info there.

Anyone else? Anyone?

Cosmoline
December 21, 2007, 01:46 PM
What would you be trying to accomplish? More power? Better accuracy?

Remember old Russian proverb--the best is enemy of good enough!

If you want more accuracy, follow the Finnish example and load for the 7.62x53R with a .308" bore and match bullets. This is the one they use for competition over there as I understand it.

But I may not be understanding it. Can you draw out your plan using this as the base?

http://www.stevespages.com/jpg/cd762x54rrussian.jpg

silverlance
December 21, 2007, 02:26 PM
cosmo, as i understand it the finn guns are about .311, just like the russians. are you saying that there is a separate breed of finn MNs that are 308 barreled?

according to the load books, many companies insist that MNs are 308 "but are often .310 to .312" which means you usually have to slug the bore.

i reload using .311 (303 brit) bullets.

fireflyfather
December 21, 2007, 03:59 PM
Silverlance: All mosins need to be slugged, but the Finn's are MUCH more likely to be at .308 or thereabouts than any other mosin.

Cosmoline
December 21, 2007, 04:13 PM
cosmo, as i understand it the finn guns are about .311, just like the russians. are you saying that there is a separate breed of finn MNs that are 308 barreled?

The bulk of post-Winter War Finnish rifles had .310" bores, particularly due to the massive amounts of captured 54R from the Soviets loaded with .311" bullets. They also had modifications to their chambers, indicated by a "D" stamp on some, that allowed for chambering of heavy ball. Before that they varied, but in the case of M28/30's they were as tight as .3085" or so. There is a seperate "subspecies" of match rifles bored in that same tightness that they use, and some consider these the true x53R's.

ALmost all Mosins on the market today are set at .310" to 311", with some getting wider because they were rebored by the Soviets. The pre-Winter War Finns are a rarity.

W.E.G.
December 21, 2007, 04:52 PM
What, the recoil isn't already enough for you?

rcmodel
December 21, 2007, 05:11 PM
Seems to me the only way "Improving" it would do anything useful was if you could run higher pressure with more powder.

And you can't.

The Mossy is a 45,000 - 49,000 PSI rated action no matter what you chamber it for.

Not to mention they are all getting really old!

http://i81.photobucket.com/albums/j219/rcmodel/KTOG/1224.gif
rcmodel

cracked butt
December 21, 2007, 05:17 PM
Seems to me the only way "Improving" it would do anything useful was if you could run higher pressure with more powder.

Doing an AI treatment means more case capacity so that you can use more powder without raising pressures.

It should work, but the only question is why bother?

rcmodel
December 21, 2007, 05:30 PM
I understand perfectly how "Improved" cartridges are "supposed" to work.
And they did back in Ackley's day, before pressure testing was so widely used.

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!

Burning more powder doesn't increase velocity significantly unless there is a corresponding increase in pressure.

When Ackley's "Improved" cartridges are held to the same pressure as the parent cartridges, the is little or no increase in velocity.

And with the Mossy's almost 30" barrel, and todays slow powders, I imagine there is more to be gained there then by blowing out the case.

Case in point: Is the .300 Weatherby faster then the .308 Winchester because it holds more powder?
Or because it operates at 13,000 PSI higher pressure?

http://i81.photobucket.com/albums/j219/rcmodel/KTOG/1224.gif
rcmodel

JesseL
December 21, 2007, 05:34 PM
Burning more powder doesn't increase velocity significantly unless there is a corresponding increase in pressure.

Unless you burn more of a slower powder to stretch out the pressure curve without making it any higher -- but I suspect you'd still only see significant gains if you're working with unusually long barrels.

rcmodel
December 21, 2007, 05:41 PM
Are you out of room for slower powder with the standard Mossy case?
That's what I was getting at.

Some of the newer powder available now is quite dense, and a lot of it would fit in a standard case.

http://i81.photobucket.com/albums/j219/rcmodel/KTOG/1224.gif
rcmodel

silverlance
December 21, 2007, 10:18 PM
thanks for the info guys. I've put .311 bullets down pre talvisota finns... I guess 308 is big enough for 311! =( yikes

hm.. how about raufuss for 7.62x53r?

230RN
December 21, 2007, 10:56 PM
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.

_N4Z_
December 21, 2007, 11:31 PM
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.

How long?

This round in it's maiden form was/is already capable of respectable distances. BC's on new factory and surplus ammo can be quite impressive. Even plain jane Brown Bear 185fmj runs with a bc of .516. Not too shabby.

As far as recoil - I say on par with 30-06. Some have told me they think it's a touch stouter.

Move away from the computer and go fire one for yourself. ;)

230RN
December 21, 2007, 11:57 PM
N4Z suggested,

Move away from the computer and go fire one for yourself.

Good advice. But can't take it for a while, and I know from experience that experience always trumps just noodling around with an idea.

Anyhow, as I said, I was just skylarkin', and the idea jumped out at me. And if you'll note in Post 2, JesseL suggested the same thing a year ago, so it's not a way out idea. I still can't see that the recoil would be worse than a Springfield, unless it's because of the shape of the stock/butt. I noticed that when I shoulder the rifle, it doesn't "sit" quite right on my shoulder without some fiddlin' and fussin' and squirmin' around a little.

TimboKhan
December 22, 2007, 02:03 AM
I'm wondering if all the tales about recoil and muzzle blast and flash aren't with respect to the carbine only.

They are not, but there is some hype related to both. Recoil being subjective, I don't find it that bad in either version, and I have a bad shoulder. The fireball is less in the rifle, but it is still pretty impressive. Personally, I find the Mosin pleasurable to shoot, although I will say it is freaking loud.

cracked butt
December 22, 2007, 03:05 AM
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.


That's my whole point about 'why bother'

Unless you have a finnish M-N, the typical 91/30 with its corn cob rough barrel isn't going to give you enough accuracy to take advantage of extended range from higher velocity beyond what the cartridge is already capable of.

Cosmoline
December 22, 2007, 03:17 AM
Actually the 54R, like the 8x57JS, is already pretty maxed out in its ball loading. You can squeeze a wee bit more out of them, but not much. The one from that era with real room for improvement and development as a longer range light magnum is the big old .30'06.

GD
December 22, 2007, 09:02 AM
The only Finn Mosin that I am aware that remained in .308 was the M28/30. If they are not D stamped, you should expect them to be .308. All the rest are .310-.311.

Langenator
December 22, 2007, 09:29 AM
If you really want to shoot long range from a Mosin action, you could go in a different direction, one also already taken by the Scandinavians, and neck it down to 7mm or 6.5mm, and get some really slick BCs.

230RN
December 22, 2007, 12:31 PM
Well, great!

At least there's a little more discussion about it this time around than appeared in the link JessL provided for the thread about this a year ago, which was:

http://thehighroad.org/showthread.php?t=218714

Apparently, though, my position on the recoil not being greater than in the Springfield is wrong. Many people seem to have observed a greater kick than in the Springfield.

Or at least "a lot" of kick. Maybe they just haven't fired a .30-06, or are just used to the military varmint round.

Interesting. One would expect it to be less because of the pressures, bullet weights, and barrel lengths involved, but of course there's a slightly greater exit area in the M-N than in the Springfield, roughly* .0745 sq in in the .308 diameter Springfield, versus .0759 sq in in the .311 diameter M-N.

Exit pressure on the 24 inch barreled Springfield is around 7000 psi. I don't know what it is for the M-N 26.5 inch barrel.

Of course, there's that buttstock on the M-N, which is smallish and just plain shaped "funny."

One of the most punishing guns I ever fired was a 69 caliber Zouave (BP). Its buttstock was obviously designed to punish the party in the rear as much as the party in the front.

OK. Not the worst idea I've had while just "skylarking," but not the best, either.

Thanks, all, and I guess I won't be cutting that D-reamer for a 7.62 X 54 R Improved after all.

------
* I'm neglecting bore diameter here, just for a rough calculation for a quick comparison.

benEzra
December 22, 2007, 01:32 PM
One other thought--how malleable are steel cases compared to brass cases? I'm wondering if you moved the shoulder forward, would a steel case fireform to the new dimensions when fired like a brass case would, or would the steel split, giving you case rupture problems?

I wonder that because a lot of the available ammunition for 7.62x54 is steel cased, and it would be easy to fire steel cased ammo by accident.

Langenator
December 22, 2007, 02:41 PM
Everything I've read has said that reloading steel cases is not something you really want to do.

JesseL
December 22, 2007, 02:47 PM
Everything I've read has said that reloading steel cases is not something you really want to do.

I think benEzra was just referring to firing standard surplus or russian commercial steel cased 7.62x54R ammo in a 7.62x54R Improved chamber; not necessarily reloading steel cases. One oft the oft mentioned advantages of an Ackley Improved type chamber is that they usually retain the ability to use standard factory ammo.

230RN
December 22, 2007, 08:03 PM
One of the oft mentioned advantages of an Ackley Improved type chamber is that they usually retain the ability to use standard factory ammo.

Thanks, JesseL, that's part of what I had in mind. But it's only true if you don't blow the taper out of the case walls of the Improved version. That's why I was thinking of just moving the shoulder forward and taking some of the taper out of the shoulder, not the whole case.

The business of necking up or down was not part of what I was thinking of doing. I was thinking of the possibility that for normal use, you could use the factory rounds (they'd get blown out, of course), and use the Improved version for longer range shooting.

Well, like I said, this was a fun lark, and I learned a lot. I'm still fascinated by what can be done with that nice, looooong 26.5" barrel. But if it ain't practical, it ain't practical.

I stuck the bayonet on it, and wow, is that one long heckova hunk of shootin' apparatus! LOA five feet, five and a half inches. En garde!

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