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7.62X54R


rivitir

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I'm having some trouble understanding something I hope you guys can help me clear up. I have been doing a lot of research on Mosin Nagants and the 7.62x54r round and I found that their are a couple of different diameter bullets for this rifle but all are named as 7.62x54r (am I crazy?). I have not checked my barrel yet but I know of others that have found they have either a 7.62 (.308) or 7.92 (.311) and I also heard of .310! When I've looked at various reloading sites and other sites they are all different but mostly reference 7.62 (.308) or the 7.92 (.311) bullets.

 

Why are their different diameters? Does one shoot better then the other?

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I just found this conversion calculator http://www.worldwidemetric.com/metcal.htm

and 7.92mm is .311 inches!

 

ROFL!

 

Google can do conversions for you as well, just search for "7.92mm to inches" and it will say:

7.92 millimeters = 0.311811024 inches

 

Here is a shortcut to Google calculator:

http://www.google.com/intl/en/help/features.html#calculator

 

So does one diameter shoot better then the other? Is their a reason why their are different diameters?

FYI... I also heard that their is a 6.5x54r, its a wildcat round. Something that would be fun to try, that and maybe a 7mm.

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Is it that folks on that side of the Atlantic Ocean refer to land diameter and we refer to groove diameter?

 

Speaking of 7.92MM.....

That is how the '8MM Mauser' (.323 groove) is referred to sometimes and as it works out the land diameter is .311.

 

I always thought that 7.62X54R was a .311 bullet ( groove diameter). I haven't measured it but I'd guess that the land

diameter is just about .308.

 

Tinker :blink:

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I think the metric conversion of .311 would be 7.7 mm like the Jap round.

From my machinist reference book:

 

.303"=7.7mm (actually 7.6962) = bore size

 

.312"=7.9248 = groove size

 

I think the Russian's measurements were a little off when they called it a 7.62.

 

With the 8mm mauser (JS) the bore size was .312" (7.92mm) and the groove size was.323" (8.2042mm)

 

The original 8mm mauser groove was .318" or 8.0772mm

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From my machinist reference book:

 

.303"=7.7mm (actually 7.6962) = bore size

 

.312"=7.9248 = groove size

 

I think the Russian's measurements were a little off when they called it a 7.62.

 

With the 8mm mauser (JS) the bore size was .312" (7.92mm) and the groove size was.323" (8.2042mm)

 

The original 8mm mauser groove was .318" or 8.0772mm

 

I'm sure I'm not understanding this correctly, so please correct me if I'm wrong.

 

Bore size refers to the actual inside diameter of the barrel this includes the rifling?

Groove size is the diameter of the barrel not including the rifling?

 

So for the Mosin, if your bore size is .310 then you would want to shoot a bullet through it sized .311 or maybe .312 in order for it to grab rifling? And I would assume it would not be safe to fire anything larger (ie: .323) nor smaller (ie: .308)?

 

And if your Mosin has a .307 bore then you would want to shoot a .308 through it?

 

Sorry for all the questions. I just want to make sure I understand this correctly.

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Much of this confusion arises from the fact that different folks are all describing the same thing differently.

 

First of all, 1 inch = 25.4 millimeters EXACTLY.

 

Secondly, as stated, European countries tend to use "land" diameter, and the US tends to use "groove".

 

Rifling averages around 0.004", so factoring both sides, that's ABOUT 0.008"

 

Some European numbers, ideally representing LANDS:

 

7.62mm / 25.4 = 0.300" (add 0.008 to get 0.308) Ex: .300 H&H Magnum

 

7mm / 25.4 = 0.2755" (add 0.008 to get 0.2835 or 0.284) Ex: .276 Rigby

 

7.92mm / 25.4 = 0.3112" (add 0.008 to get 0.320)

 

7.65mm / 25.4 = 0.301" (add 0.008 to get 0.309)

 

6.5mm / 25.4 = 0.256" (add 0.008 to get 0.264) Ex: 256 Newton (yeah, it was really a .264)

 

6mm / 25.4 = 0.236" (add 0.008 to get 0.244)

 

All of the above seem to fall in line (the 7.65 seems a little low, but I wasn't there when they named it).

 

The British seemed to use both land and groove measurements depending on the phase of the moon; the .300 H&H uses .308", but the .375 H&H uses .375".

 

9.3mm fails the above tests, as it converts to 0.366", which would be grove, not land. Perhaps the Germans liked to play a little loose with numbers for marketing...

 

I think another issue, and that is one that affects the 7.62X54R, is the term "caliber". Caliber is usually written and spoken to two significant figures. Both the .303 British and .308 Win are "30 caliber", despite using different diameter bullets. My guess is that the Russians were thinking this as well, or they translated it as such. So 7.62mm is "30 caliber" rather than ".300 land diameter".

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Since we're on the subject, why does the 44 special and the 44 mag use .429 bullets?

Doesn't that make it a 42 caliber or 43 at best?

Also the .38 special uses .357 bullets, isn't that a 35 cal, not a 38?

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Since we're on the subject, why does the 44 special and the 44 mag use .429 bullets?

Doesn't that make it a 42 caliber or 43 at best?

Also the .38 special uses .357 bullets, isn't that a 35 cal, not a 38?

 

Good question. My understanding of the situation is thus:

 

Early cartridge bullets were "heeled"; i.e., the major diamater of the bullet was the same as the outside diameter of the case. The rear or base of the bullet was stepped-down to fit into the case.

 

At some point, someone figured that it would be easier or advantageous to eliminate the bullet heel. Unfortunately, they kept measuring the bullets by the outside diameter of the case, at least for a while.

 

The .44 (Russian, Special, Magnum) and .38 (Colt, S&W, Special) should be the only cartridges that fall under the older system and were "mis-named".

 

We still have "heeled" ammo today... it's called the .22 Long Rifle. The outside of the case is the same diameter as the bullet diameter. Talk about a throwback!

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My head is starting to hurt :( . I would just use .311-.312 diameter bullets in my Mosin Nagant and forget about it.

 

Do you reload for your Yugotine? If so, what bullets do you use?

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Good question. My understanding of the situation is thus:

 

Early cartridge bullets were "heeled"; i.e., the major diamater of the bullet was the same as the outside diameter of the case. The rear or base of the bullet was stepped-down to fit into the case.

 

At some point, someone figured that it would be easier or advantageous to eliminate the bullet heel. Unfortunately, they kept measuring the bullets by the outside diameter of the case, at least for a while.

 

The .44 (Russian, Special, Magnum) and .38 (Colt, S&W, Special) should be the only cartridges that fall under the older system and were "mis-named".

 

We still have "heeled" ammo today... it's called the .22 Long Rifle. The outside of the case is the same diameter as the bullet diameter. Talk about a throwback!

 

AH! Now that makes sense... I just measured one of my 7.62x54r bullets and it is .307 under the brass and .310 outside!

 

Thank you for the post gun nutty. Very helpful.

 

So if your "groove" (.008 smaller then the "land" diameter) is .310 do you want to use .310 bullets or should you use .311 or .312 for best accuracy?

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No, not with the 7.62x54R. It was NEVER a "heeled" bullet. The only modern rounds that fall in this category are .44 (Special, Magnum), .444 Marlin (because they like to regress), .38 (Special, Colt, S&W) and maybe .32 (Magnum, Long).

 

7.62x54R/7.62x53R bullets can vary anywhere from .307 to .313 depending on country, factory, or tide condition. It has nothing to do with the outside diameter of the case.

 

The Finns liked .308 bores, other countries liked them more open.

 

I'm adding this note:

 

The .44 Magnum, .44 Special, .38 Special, .444 Marlin, and other modern rounds were never actually heeled bullet ammunition. They are following the system implemented for naming the older cartridges.

Edited by gun nutty
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No, not with the 7.62x54R. It was NEVER a "heeled" bullet. The only modern rounds that fall in this category are .44 (Special, Magnum), .444 Marlin (because they like to regress), .38 (Special, Colt, S&W) and maybe .32 (Magnum, Long).

 

7.62x54R/7.62x53R bullets can vary anywhere from .307 to .313 depending on country, factory, or tide condition. It has nothing to do with the outside diameter of the case.

 

The Finns liked .308 bores, other countries liked them more open.

 

This is wolf ammo, I measured it right at the brass (steel case) and then a little farther up. Thats how I got the 2 measurements. It could be a crimp ring which may be the reason it is smaller.

 

Is their much difference in BC between .308, .310, & the .312 bullets?

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Is their much difference in BC between .308, .310, & the .312 bullets?

 

For similar bullets of similar weight, yes; i.e., a Hornady 180 gr SP bullet of the same style for .308 and .311 diameters should have a similar BC.

 

I wouldn't worry about BC as much as terminal performance. I've had hunting grade SP bullets outshoot glow-in-the-dark boattail bullets. How does the bullet group on paper? How is the expected performance on target (paper or a lung shot)?

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To add to the confusion!! Foreign mil-surp ammo projectile sizes vary as much as rifle bore sizes do. I haven't paid much attention to 762X54R but I've had mil-surp 762X39 ammo with projectiles as small as 308 and as large as 313. Best I recall most was 309-310 if the projectiles were magnetic and 311-312 if not.

 

Confused yet?? If the 44 is actually .429, why does a 44 cal cap and ball revolver use a 45 cal ball?? Unless the 44 cap and ball revolver is a Rugar then is uses a 46, well actually .456. Guess somebody used the same logic when they named the Maxi-ball.

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To add to the confusion!! Foreign mil-surp ammo projectile sizes vary as much as rifle bore sizes do. I haven't paid much attention to 762X54R but I've had mil-surp 762X39 ammo with projectiles as small as 308 and as large as 313. Best I recall most was 309-310 if the projectiles were magnetic and 311-312 if not.

...

 

Interesting. So could shooting a .308 or .312 bullet in your .310 bore cause you or your rifle damage? Ultimately I'm trying to avoid that in my hobby. :lol:

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