7.62x39mm accuracy/bullet size


PDA






just_another_citizen
January 29, 2003, 11:12 PM
Some 7.62x39mm ammo has a .308 bullet diameter, some a .311 bullet diameter.

My barrel is .311 internal diameter, wondering how firing the smaller bullet might affect accuracy. [rattling around]

Or vice versa, firing the .311 bullet through a .308 bore. [squeeze]

I thought the external dimensions of commercial ammo were standardized... it seems like a different bullet diameter would be a different "caliber".

Anybody know why this discrepancy exists?

But that's just me. I wonder if this is one of those cases where "that's the great thing about standards, there are so many of them !!"

If you enjoyed reading about "7.62x39mm accuracy/bullet size" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!
Smokey Joe
January 30, 2003, 02:33 AM
I've just done the math, and 7.62mm does not equal .308". Nor does it equal .311". These designations are done arbitrarily, for a variety of reasons, and make a fascinating historical study, if you have the time and the inclination. But your question was, why have 2 different calibers designated 7.62x39mm.

Russian military designers thoughtÑfor whatever reasonÑthat .311" was a nice diameter for their 7.62 rifle barrels when they designed the so-called 7.62x39mm round. (They whould have used a metric measurement for this however.) That round went through the various SKS models, and the various AK models, the latest of which are still in use. The same standard was used by the Chinese, and the other nations to which the USSR/Russia exported weapons-building technology, from the 1950's through the 1990's. So there are lots and lots of old military weapons designated 7.62x39mm, with this bbl diameter.

When Ruger subsequently decided to chamber their Mini 30 in this round, in their infinite wisdom, they chose to make the bbl. diameter .308", for whatever reason. Perhaps because other cartridges popular in this country, which are called 7.62mm elsewhere, are .308" diameter. Notably the .308 win, aka the 7.62 NATO. I'm not representing this as good logic, you understand, but it's what Ruger did.

So from two different sources, you have the same round with 2 different diameters. :mad: A potentially dangerous situation.

If you had a .308" diam. 7.62x39mm bbl, and fired the .311" diam ammo in it, the best you could hope for would be a ferocious kick and lousy accuracy, as the large bullet is violently forced to conform to the smaller bbl. Internal pressures would be I think, dangerously high. Gun damage and damage to shooter or bystanders are worse case scenarios. So you would be well advised to stick with domestic American sporting rounds, which are .308" diam.

If, OTOH, as you say you have, a .311 diam bbl, you should be seeking and using .311" diam bullets. The .308 diam bullets will probably upset (flatten their back ends) in the barrel and seal the bore, but they will probably NOT do so pointing straight down the bore, which means they will be headed God-knows-where when they exit the muzzle. Not a dangerous situation, but highly inaccurate, and not predictably so. If the bullets always went left of point of aim for example, you could adjust your point of aim, but when they upset in the bore they may be pointing left, right, up, down, or straight ahead. If the bullets don't upset, they'll just rattle down the bbl, with pretty much the same result as above, except with less velocity due to blow-by of some of the powder gases.

Bullets of both diameters can be had easily by reloaders, so there is no excuse in either case not to have high quality ammo for your weapon. Accurate Arms 1680 powder was designed specifically for this round, and usually works well. It seems to be the logical place to start in load development for a particular weapon.

IMHO, you have hit the proverbial nail on the head. But that's just me. I wonder if this is one of those cases where "that's the great thing about standards, there are so many of them !!" Nice way of putting it.

BTW, since you have a .311 "7.62x39mm", I hope you enjoy shooting your milsurp. :)

yzguy
January 31, 2003, 12:55 PM
I had never heard that...

so 2 boxes of ammo marked 7.62X39 may have different size bullets???

I have an SAR-1 (Rom AK-47) and am shooting wolf through it. I'm pretty sure they match in size, but which size would that be??

Duke of Lawnchair
January 31, 2003, 02:51 PM
Smokey is pretty much on par.

I'd also like to say that circa 1994, Ruger mfg'd their Mini30s to allow them to be more combloc 7.62x39 "friendly". There are some lots of 7.62x39 that are .310 OR .311. If I'm not mistaken, the .310 slugs are Czech in origin. Not that you couldn't shoot the combloc ammo through older mini30s.

From Brownells:
------------------------------------------------------------------------------------
Ruger Mini Thirty Bore Specifications

This information pertains to:
Ruger

Answer:
This rifle is chambered for the 7.62 x 39mm cartridge. This cartridge, traditionally, uses a projectile with a nominal diameter of .311 to .312 inch.
At the time the Mini Thirty was introduced very few bullet makers where producing .311/.312 inch bullets for reloading in the light 125-130 grain weight required. Ruger initiated the use of barrels with a groove dimension of .308 inch and a long tapered throat. The throat allowed the use of ammunition with .311/.312 projectiles by gradually “squeezing” them to the .308 diameter. In addition, ammunition loaded with more commonly available .308 diameter bullets could also be used.
Commencing in 1992 Ruger initiated a change to using .311/.312 nominal groove diameter, 1-10 inch right hand twist barrels in all Mini Thirties. It was likely well into 1993 before all rifles coming of the production line incorporated the .311/.312 barrels.
------------------------------------------------------------------------------------

I have confirmed this with Ruger as well in regards to my very own Mini30, which unfortunately was mfg'd in '91. Bummer...

Jim

Smokey Joe
February 1, 2003, 10:35 PM
YzguyÑYour Romanian AK is a combloc gun (design of Russian origin). Wolf (Russian) is "modern" combloc ammo. Ergo, they match and can be used safely together. Enjoy.

FWIW, I don't think much of steel-cased ammo with Berdan primers. Inaccurate in my experience, hard on some guns (although combloc guns generally have no problem digesting it) and of course utterly non-reloadable. Cheap, sure. But if you do anything involved with shooting to save money, IMHO, you are in the wrong hobby area. We don't shoot to save money, we shoot to put the bullet in the target.

You can get a set of brass 7.62x39mm cases, primers, AA 1680 powder, 125 gr. .311 bullets (Hornadys work for me), and FL resize loading dies at the next gun show you go to. You can manufacture better ammo than Wolf on your first try. Get
The ABC's of Reloading and read it if you don't reloadÑReloading is part of the fun! Most any reloader, of your acquaintance or online, will be willing to help with problems or questions as they arise. Read and obey all the cautions. We are, after all, dealing with rather powerful chemicals and large forces, here. Not dangerous unless you do something stupid. You can beat the price of store ammo, over the life of your equipment, but you don't reload to save money, you do it to make better ammo for YOUR GUN than that of which any factory is capable.

BTW, there's one other 7.62x39mm complication: Remington brass for that case uses small rifle primers; the other manufacturers all use large rifle primers. So match the primers to the cases you buy. I don't know why SAAMI didn't get on Remington's a** about this; I thought that was what SAAMI was for, but there you are. Either use all Rem. cases for this cartridge, or no Rem. cases, and no further problem. Before I started loading for this caliber I never heard of such a thing. I hope I never do again. That comment above, about standards, comes to mind once again.

Sir Galahad
February 1, 2003, 10:50 PM
Who the hell wants (or needs) to reload for an AK-47? My SAR-1 ejects so far, I'd hate to be policing up brass and worrying about strays getting lost. Wolf ammo is cheap and runs great out of AKs. Wolf and Barnaul ammo is the way to go for AK owners.

Smokey Joe
February 1, 2003, 10:57 PM
I the hell want to. For the reasons stated above. If you don't want to, it's all right with me. But I promise I won't knock your decision in public.

Sir Galahad
February 1, 2003, 11:05 PM
I'm not knocking your decision. But I think most AK owners will agree that an AK shoots just fine with Russian ammo. Mine does. You can save money shooting. It doesn't have to be expensive. That's why Russian 7.62x39 Saiga rifles and Wolf ammo sells like so fast they never collect speck one of dust in many gun shops.

But when I really want to save money, I shoot my Martin recurve bow. I can reuse that ammo again and again. :D

benewton
February 2, 2003, 12:45 PM
Smokey:

Galahad has it about right in this case, I think.

I can't buy the bullets for the cost of the Wolf stuff, purchased in case lots.
Plus, I use a MAK 90, with new wood, for close in defence, so MOA accuracy isn't an issue.
Reliability isn't a problem, so I guess I got a good ($200) rifle, for the purpose that I intended, of course.

In any case, I can't buy the bullets for reloading for the cost of the Russian loaded rounds...

I like to think of it as a bigger .22 RF!

Besides, sometimes it's fun to shoot without worrying where the "brass" is flying.

Meanoldfart
February 2, 2003, 09:45 PM
You guys are getting exercised about nothing.
Practically since firearms have been made, the caliber designation has been the hole size drilled in the barrel.
I'll skip all of the OLD bore sizes and get to one we all recognize:
.30-06, a.300 hole drilled in the barrel in 1906, {7.62mm is exactly .300in.}
Enter the .30-54{or whatever year the .308 Winchester aka 7.62x51Nato was developed}which happens to have a hole drilled in the barrel of exactly .300in.
The reason it was called the .308 was that Winchester wanted to have a propietary name so they added the depth of the rifling which was .004 on each side or a total of .008in. so we have a hole .300in+grooves of .008={voila} .308.
Today, I slugged the barrel of one of my Chinese SKS's with soft lead{i'll measure it tommorrow when I get to the shop}, however, I did notice one strange thing that I had never seen before, the grooves are twice as wide as the lands.
All rifles I have slugged in the past, the lands and grooves are equal.
This means that with a hole of 7.62mm or .300in, if the grooves are twice as big as "normal" rifling, it will take more bullet{more diameter} to fill the grooves.
With out even taking this into consideration, I doubt that any of these military rifles have a barrel whose rifling is within .002in. or .003in. for it's entire length.
I suggest that you get a ruler that is measured off in 100ths of an inch and then imagine that the distance between each of those marks is divided into 10 to give you1/1000 of an inch.
I will assure you that a difference of .003in will make no measurable difference in accuracy or pressure.
MOF

Gewehr98
February 4, 2003, 01:51 PM
In fact, save for about one magazine's worth of that green-lacquered Wolf stuff, the gun has never digested anything other than my handloads, and it's got about 5K rounds through it.

Funny thing is, I've gotten some witnessed groups out of the Bulgarian SLR-95 with my handloads that go inside 2" at 100 yards. Try that with Wolf ammo. Granted, the AK isn't intended to be a benchrest gun. But I can live with a 2 MOA AK, no problem!

I have confirmed this with Ruger as well in regards to my very own Mini30, which unfortunately was mfg'd in '91. Bummer...

Why is that a bummer? You've essentially got a 2-bore rifle there. You can shoot both the cheap milsurp ammo, and earlier domestic (Winchester, Federal, Remington) 7.62x39 fodder. If you were to handload for that throated Mini-30, say, using a .308" spitzer bullet, you could very well dispute the notion that all Mini-30's are inaccurate. That Ruger's tapered throat may surprise you. Weatherby did the same thing, but they call it free-boring, and use it to keep pressures down from those big belted magnum rounds.

Does that .003" difference in bullet diameter make a difference? Shoot a .308" bullet from a .303 British Lee-Enfield, or Arisaka, or AK. See what your groups do. Or should I say, see how your patterns do. Having thought the same thing as meanoldfart above, I ran some experiments. Been there, done that, got the t-shirt.

I even swage down .323" 8mm Mauser bullets to .321" for my .32 Remington Model 8 rifle, using a Corbin swage die. Maybe the safety and accuracy freak in me is showing, but if the barrel mikes out at a certain diameter, I go with bullets matching it, especially if it's not a throated barrel.

Several 7.62x39 Contenders, SSK Handcannons, and MOA Maximum pistols were built for the handgun silhouette game, where steel silhouettes out to 200 meters were toppled with surprising regularity using the cartridge. Neat thing was, domestic brass was used, but the barrels were true .308" bores. If you haven't noticed, there is a buttload more selection in the .308" bullet diameter than in the .311" flavor. When practicing for a local IHMSA match one afternoon, a friend turned a 100 meter silhouette sideways with his revolver, so the edge was facing him. He rather unceremoniously grabbed his scoped .308x39 SSK/Contender, and proceeded to hit the edgewise silhouette squarely.

Were I to build a 7.62x39 bolt gun, I'd probably use a .308" barrel, just so I could run decent bullets. ;)

Smokey Joe
February 6, 2003, 02:55 PM
GewehrÑOn the website, www.sixgunner.com Paco Kelley wrote of a 7.62x39 bolt gun, and was quite enthusiastic about it as a heavy varmint/light hunting/short range accurate cartridge. By short range he meant under 200 yd I believe. Paco called the round in this rifle "a .30-30 on steroids." I've never seen nor heard otherwise of a bolt gun in this cartridge. It certainly seems like a very interesting proposition.

Such a rifle could be quite accurate w/o being nearly as heavy as usual in an accurate hunting rifle.

zeke
February 10, 2003, 08:59 PM
Gewehr98-Am starting to reload for a Bulgarian, can you share your accuracy receipe? Am starting with Lapua brass, Speer softpoints (.311) and HDY's new plastic tips (.310). Any suggestions or tips would be appreciated.

Gewehr98
February 11, 2003, 09:05 AM
Accurate Arms 1680 is the best powder, bar none, for decent 7.62x39 handloads. Best velocity, lowest pressure signs, and clean burning. Problem is, I'm having trouble finding even a single pound of the stuff here in Spacecoast Florida. :(

If you can't find AA1680, Hodgdon's H335 will work until you can find AA1680.

I've used the Hornady 123gr FMJ bullets, as well as the Winchester bulk FMJ bullets. More recently, places like Wideners, Natchez, and MidwayUSA offer South African or Russian .311" 123gr FMJ bullets. Regardless of who made them, I do a cursory diameter check on the batch, as well as weight sort the surplus military bullets.

I have used the Speer softpoints, they shoot just fine. I didn't know there was a .311" plastic-tip bullet, that's another one I will have to try.

I use a pretty good crimp on my 7.62x39 handloads, just to keep a bullet from being pushed back into the case during the rifle's cycling. It's not really a problem, the bullets I use have the cannelure for that, and it's done with a Lee Factory Crimp die.

Poodleshooter
February 11, 2003, 04:10 PM
Gewehr, if you shoot enough of it, www.gibrass.com has the czech powder that AA imports as 1680, available in 8lb kegs for fairly cheap.

Gewehr98
February 11, 2003, 05:05 PM
I'd almost given up trying to find it, without resorting to buying a case of the stuff. The local reloading shop doesn't have much call for AA1680, and won't stock it if there's only one odd bird who needs it. (me) ;)

My current supply was bought in Wisconsin when I went home for Thanksgiving. Wife thought I was nuts to have a pickup box full of reloading supplies going from Wisconsin to Florida. :D

zeke
February 11, 2003, 07:47 PM
Gewehr98-Thanks much, it is appreciated. Graph and Sons lists AA 1680 in 1 and 8 lb jugs. They are also the only source (am aware of) for HDY's 123 gn V-Max bullets (advertised and measured .310 in dia.). They have significant savings for bulk orders.

Had to pass up a CZ carbine in 7.62x39, that had an absolutely beautiful stock and less than 1 in factory group (including a flyer). Was there when dealer unwrapped it, didn't have cash on hand before it was put away in the dealer's private collection.:banghead:

just_another_citizen
February 18, 2003, 12:34 AM
thanks to all for the info !

Jedi_7.62
February 18, 2003, 01:21 AM
I get 7.62 x 39 ammo sometimes wolf sometimes other surplus for about $100 for a 1,000 round case .10 per bullet and think they shoot fine I'm sure there is better stuff out there but my question is ..is reloading AK ammo worth it?

I don't reload but would like to get into it someday when I have time, money, and space.

How much money would you save and how long would it take to reload a case of ammo?

Oh and while on the subject how many times can brass be reloaded?

I've been on this forum about a month and learned more than a semester worth of College classes.

Dot_mdb
February 19, 2003, 02:52 PM
Jedi,

You won't save money by reloading 7.62x39. I just bought a couple of cases of Wolf ammo from Centerfire Systems for $80 each including delivery. That is 8 cents a round. If you reload for 7.62x39 the powder will cost you that much.

The only reason to reload 7.62x39 is to get a higher quality and more accurate round. You would save money compared to a high quality factory round which might cost you 50 cents each.

Bill

GooseGestapo
February 19, 2003, 04:19 PM
The original question was regarding the loading of .308 bullets in the 7.62x39.
My answer is that there is no problem with it and accuracy is not a concern. I've loaded 125gr Nosler BT's (.308's and other .308" dia. bullets) and gotten outstanding accuracy, best of ANY bullet of either .308, .310, .311, or .312. Admittedly, the .312's of jacketed construction had the poorest accuracy, but no pressure signs were encountered. Ed Harris had a column in the American Rifleman several years back and stated he had the same results. Curtis Shipley of Ga Arms/Master Cart. let me in on his load for the 7.62x39 and it worked for me too:
Commercial US brass (I prefer the R-P w/ Small rifle primer)
Federal 205 primer
Nosler 125gr Ballistic Tip
AA-1680 (I use 26.5gr)
Seat to fit Magazine (fairly deep)
My three Norinco SKS have given approximately 2"groups at 100yds. A friends early Mini-30 (with conical throat) would give 1.5" groups, and would give 1" (3-shot) groups with H-322 (lost data card with weight).
So, try the .308 bullets in your rifle.
For what its worth, my favorite load is a 153gr Cast Ptd GC Lee over 17.5gr H4227 for approx 2050fps. sized to .311". It too gives 1.5" groups @ 100yds (3-shots). This bullet gives 1.0" 5-shot groups out of my two .30/06 bolt actions @ 2100fps over 25.0gr of H4227 or Alliant 2400.
So much for bullet/barrel diameters !!!
What works....works. 1-2 thousanths dosen't make a world of difference.
Just don't try shooting .323 bullets through a .318 bore, or .308's through a .284" bore. And .25/06's aren't real accurate through a .30/06, watched a fella try to sight in his Rem 700 one day doing that. WOW what a pattern !!! 2ft at 25yds, all sideways !

SodaPop
February 19, 2003, 07:23 PM
I use to reload for the 7.62x39 before I was any good with a rifle. I used RX7 with Winchester 123gr bullets. I think consitant powder drops improved groups by 90%. I think thats the biggest problem with most 7.62x39 manufacturers. Most of them drink too much Vodka.

If you enjoyed reading about "7.62x39mm accuracy/bullet size" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!