Interesting differences in the 7.62 (.30) caliber bullet...

[SteelCore]

Hey, after shooting this weekend, a buddy of mine and I kicked back with some cleaning products and some Bourbon. He had the calipers out, and we were talking about the .30 caliber bullet, and how many of them had a slightly different diameter..."What?!?" the buddy said..."No Way."

So, I says, heres three diff .30 cals I have right here, lets measure the projectile diameter. Here were our findings:

Argentininan (CAVIM) 762NATO:____.306"
Russian (Wolf black box) 762x39:___.308"
Bulgy 762x54R:__________________.310"

Then, we thought, hey, let's measure that last number in the equation, the millimeters for case length:

Argentininan (CAVIM) 762NATO:____51mm
Russian (Wolf black box) 762x39:___38.5mm
Bulgy 762x54R:__________________53mm

So the Wolf was dead nutz .308cal, but the CAVIM was right on the money for case length of 51mm.

Sorry, just some things that make the drink-riddled shooter's mind go "Hmmmmm..." :beer: or mebbe it was the fumes from our gun cleaning solvents:crazyeyes2: ...the world may never know.

[Private Fuzzy]

Interesting. I have heard of 7.62x54R being different sizes such as .311 or .310.

[Genocide]

Interesting. I have heard of 7.62x54R being different sizes such as .311 or .310.

I believe your thinking of x54R/x39 rifle barrel diameter being .311/310. (don't quote me):toothless:

[Private Fuzzy]

I believe your thinking of x54R/x39 rifle barrel diameter being .311/310. (don't quote me):toothless:

That may have been it. Oops, I just quoted you.:1087:

[Geilt]

My understanding was that these rounds were all in the .30 caliber family but not necessarily dead on .30 caliber diameter. The number after the 7.62 is the actual bullet diameter in milimeters. This would go along with the 7.62x51 (51mm diameter), 7.62x39 (39mm diameter) and 7.62 x 54R (54mm'ish diameter) designations.

In the case of 7.62x54R the bullets may be 53.5mm but rounded up to 54mm for ease of referrence or the inability to consistantly attain that level of precision. This was Soviet era Russian after all and not known for it's ability to achieve exacting precision mass produced materials.

[okie shooter]

One other thought, is some calibers are denoted by diameter of the lands vs others by diameter of the grooves.

[cma g21]

So, I says, heres three diff .30 cals I have right here, lets measure the projectile diameter. Here were our findings:

Argentininan (CAVIM) 762NATO:____.306"
Russian (Wolf black box) 762x39:___.308"
Bulgy 762x54R:__________________.3085"

You got me curious, so I just measured some of mine:

Venezuelan (C.A.V.I.M.) 7.62x51mm NATO: - .308" *
Russian (Wolf military classic) 7.62x39mm: - .310"
(don't have any 7.62x54r).

*= average found one at .307", one at .309:, four at .308"

[MID]

My understanding was that these rounds were all in the .30 caliber family but not necessarily dead on .30 caliber diameter. The number after the 7.62 is the actual bullet diameter in milimeters. This would go along with the 7.62x51 (51mm diameter), 7.62x39 (39mm diameter) and 7.62 x 54R (54mm'ish diameter) designations.

In the case of 7.62x54R the bullets may be 53.5mm but rounded up to 54mm for ease of referrence or the inability to consistantly attain that level of precision. This was Soviet era Russian after all and not known for it's ability to achieve exacting precision mass produced materials.

7.62 is the diameter of the bullet in mm.

7.62 coverts to around .30 cal or .300"
The bullets have to be bigger then the barrel. They have a slight press fit for better sealing and stablization.

The second number x39 x 51 x54r.
Is the case lenght in mm.
The "R" in 54r stands for rimed. The case is rimmed on the bottom for extraction, the other ones are grooved..

Like a 7.62x39 and a 5.45x39mm
7.62 is a 30 cal bullet. And the 5.45x39 is 215 cal bullet with a 39mm case.
In fact the 5.45 case is a necked down 7.62x39 case.

.380 is a 9mm bullet.
Its kinda close to the 9x18.
The cases are just a tad different.

[okie shooter]

If you want better, .357 .38 and dont forget 9mm are considered the same family.

[Geilt]

7.62 is the diameter of the bullet in mm.

7.62 coverts to around .30 cal or .300"
The bullets have to be bigger then the barrel. They have a slight press fit for better sealing and stablization.

The second number x39 x 51 x54r.
Is the case lenght in mm.
The "R" in 54r stands for rimed. The case is rimmed on the bottom for extraction, the other ones are grooved..

Like a 7.62x39 and a 5.45x39mm
7.62 is a 30 cal bullet. And the 5.45x39 is 215 cal bullet with a 39mm case.
In fact the 5.45 case is a necked down 7.62x39 case.



Classic example of "Open mouth, insert foot". I need to stop and read the posts slower and think about what I am saying before I respond. I knew 7.62x(case length) and R standing for Rimmed. For some reason I just had diarehea of the brain when I posted my response.

[SteelCore]

Right, I made a correction. the measurement was actually .310" for the 54R..just typed wrong.

"...rounded up to 54mm for ease of referrence or the inability to consistantly attain that level of precision. This was Soviet era Russian after all and not known for it's ability to achieve exacting precision mass produced materials."

-->I think they rounded up. I would not knock soviet or russian weapons and ammo variances as being a QA issue, I just think that when you up reliability for a weapon system, you loosen tolerances to get that.(Also accuracy for the weapon may go down as a result).
[Case in point: I used the think the baltic states produced corrosive primered ammo because it was cheaper, easier, or lo-tek. After a bit of research, I founsd out that it was on purpose--the salts in the primers enable the round to be ultra-reliable in the adverse condisions it was used in....whether it is 80below or +120 degrees, wet or dry, 1year or 100years after the round was made, that thang will fire.]

"not known for it's ability to achieve exacting precision mass produced materials"
-->What, you mean like millions of milled AKs? Tens of millions of Mosins? All of which you could swap parts at random, and get the thing to work? Again, I must disagree. (I once thought like this, tho). Exacting, maybe not. Acceptable, definitely.

Okay, OKIE

So, would you class the .270Winchester as a large 20cal or a small 30cal? It is a pretty long and big bullet, with grain weights running equal or greater than a number of 30 cal loads and bullet weights.... ;)

[drhall762]

And speaking of the .30 caliber family, let's not forget the .303 Brit.

Dave :sniper:

[jfowl31]

How about the 7.5x55 swiss round? The bullet measures .308...... but the number 7.5 is given to it because thats the measurement of the lands, and about 308 is the measurement of the grooves.

calling them all 30 calibers or 7.62 is just to put them into a family... they're all a little different. You wont hurt anything shooting .308 diameter bullets through any of those bores if you reload, but the pressures will go up if you shoot 310 bullets through a 308 bore.

Ive never understood the designation of .357, and .38, and .380 auto........... thats a much bigger difference than a couple thousandths.

I was once told that the Russians used the bigger bullets so that others couldnt use them, but that sounds like total BS to me.

[nevada]

My Lyman reloading manual says the 7.62 x 39 bullet diameter should be .311" I just measured my bullets, bought before I ever thought of a caliper. and they are all .308". I know I ordered .311". They were advertised as .311". I guess now I have to slug the barrel on the MAK90. At 139gr maybe I'll try them in .308 brass.

[okie shooter]

Just remember, dont forget, they were 32 caliber bullets for the petterson device too.

[bullseye]

My Lyman reloading manual says the 7.62 x 39 bullet diameter should be .311" I just measured my bullets, bought before I ever thought of a caliper. and they are all .308". I know I ordered .311". They were advertised as .311". I guess now I have to slug the barrel on the MAK90. At 139gr maybe I'll try them in .308 brass.


Have no fear with the AK or SKS, I load and shoot 125 gr nosler ballistic tips in both with exceptional accuracy. And yes, they are .308 bullets.

[SteelCore]

"told that the Russians used the bigger bullets so that others couldnt use them, but that sounds like total BS to me."

That does sound like BS, since about 6+ countries use the exact same round in PKMs, RomakIIIs, Dragunovs, SVTs, Mosins, RPKs, etc that you see in countries that used to be Comm-bloc (Romania, Finland, Ukraine, Yugoslavia, Etc)

[Geilt]

-->I think they rounded up. I would not knock soviet or russian weapons and ammo variances as being a QA issue, I just think that when you up reliability for a weapon system, you loosen tolerances to get that.(Also accuracy for the weapon may go down as a result).
[Case in point: I used the think the baltic states produced corrosive primered ammo because it was cheaper, easier, or lo-tek. After a bit of research, I founsd out that it was on purpose--the salts in the primers enable the round to be ultra-reliable in the adverse condisions it was used in....whether it is 80below or +120 degrees, wet or dry, 1year or 100years after the round was made, that thang will fire.]

"not known for it's ability to achieve exacting precision mass produced materials"
-->What, you mean like millions of milled AKs? Tens of millions of Mosins? All of which you could swap parts at random, and get the thing to work? Again, I must disagree. (I once thought like this, tho). Exacting, maybe not. Acceptable, definitely.


I don't want to go too far off topic so I'll make it quick (which is hard for me). As to my comment about exacting precision for mass produced firearms from Soviet era factories... IMO they are intentionally a bit looser in their specs so parts from different factories will work without question and repairs will be easier. I am in no way knocking the end results. Soviet era arms can normally take a much bigger punishment than arms made in other parts of the world. I would never expect a Vietnam era M16 to make it through the same punishment an AK could withstand.

[Hoot]

Okay, OKIE

So, would you class the .270Winchester as a large 20cal or a small 30cal? It is a pretty long and big bullet, with grain weights running equal or greater than a number of 30 cal loads and bullet weights.... ;)

Actually the .270 Winchester is a western adaptation of 7mm measured at the flutes

.236
6mm
.243

.256
6.5mm
.264

.277
7mm
.284

.296
7.5mm
.303

.300
7.62
.308

.311
8mm
.32

.338
8.5mm


.354
9mm


Hoot

[hunter_la5]

I was once told that the Russians used the bigger bullets so that others couldnt use them, but that sounds like total BS to me.

er, sort of. they made sure all of their guns (I'm talking pre warsaw pact here) were chambered in different calibers than the rest of the world so that enemies could capture their ammo and use it against them.

for example, the 7.62x25mm tokarev and the 7.63x25mm mauser round were for practical purposes the same round, only slightly different in dimensions, and therefore not interchangeable between weapons

furthermore, the 9mm mak was just slightly shorter than the 9mm luger and slightly longer than the .380 ACP, and slightly wider than both. they could have just as easily gone with either already existing western round when they dropped the tokarev round, but instead developed their own round to be used exclusively by the USSR and her allies.

at least that is my understanding, I could be wrong

[nevada]

The 9 mak has a larger diameter than the .380 / 9m, too.

Shoot 7.62 Tok in a Luger and you will eventualy destroy the Luger.