7.62x39 question

hutchster

hutchster

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my rcbs die set for 7.62x39 comes with an expander for .311 installed and an extra expander for .308 diameter bullets.

i will be loading for a cz 858 chambered in the 7.62x39.

can i load with the .308 bullets or will they be to small to contact the rifling properly?

is this extra for another caliber or something?

thanks
hutchster
 
you would be better to load 311 bullets. i found some of the 308 sized didn't shoot well. noz 150 bt were good in my ruger. you will have to try a few bullets to see what your rifle likes.
 
American made ammo and rifles use .308" bullets and bore diameter(Mini-30). Warsaw Pact rifles use .331". Don't know what CZ uses. I'd slug the bore.
 
sunray said:
American made ammo and rifles use .308" bullets and bore diameter(Mini-30). Warsaw Pact rifles use .331". Don't know what CZ uses. I'd slug the bore.
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when you say .331, do you mean .311?

from what i can gather, the 7.62x39 russian cartridge is chambered for a .311 bullet, but there is only 1 bullet i can find in that diameter and it is the hornady SP 123 grn.

ideally i would like to try some different bullet weights to see which shoot best.

included in the rcbs die box is a note and an expander for .308.

the note says:

the 7.62x39 die set is assembled to use .311 bullets. if you intend to use .308 bullets, a .30 caliber expander ball is furnished and must be installed on the expander-decapping unit.

basically, i'm looking for confirmation that .308 bullets will stabilize fine even though they are 2 thou smaller, and that they won't damage my rifle due to its gas system.
 
Sierra makes 125's, 150's, and 180's. Anything you can load in a .303 will fire from a .311 bore 7.62x39mm. Heck, I have even loaded 220gr .308 and fired them nicely both sub and supersonic. Matching up a 180 to the SKS puts it right there with the .30-30 loaded with a 170 gr. Have fun.
 
Ok. This Is another 7.62 question. Why do some people say you can shoot a 308 out of a 7.62 and 223 out of a 5.56 but not the other way around. Is it because of the .311 dia in a 308 barrel (For the 7.62). I have always wanted to know the answer wether it be that it does not matter at all or what the reasons are as why not to shoot 7.62 out of a .308.
 
You need to start by slugging the bore to find out what land and groove diameter you are working with.

I just bought a Bailkal single shot rifle in 7.62 X 54. I slugged the bore about an hour ago and found the land diameter to be .301" and the groove diameter to be .312.

What I take from this is that if I shoot .308 bullets thru this barrel the rifling will be "biting" the bullet by .004" all around, the same as a .308 win, 30-06, 30-30, etc. So I think I could shoot .311 (303 Br), .308 or cast .310 bullets equally well.

When I can get to the range I guess I'll find out!
 
cdnredneck_t3 said:
Ok. This Is another 7.62 question. Why do some people say you can shoot a 308 out of a 7.62 and 223 out of a 5.56 but not the other way around. Is it because of the .311 dia in a 308 barrel (For the 7.62). I have always wanted to know the answer wether it be that it does not matter at all or what the reasons are as why not to shoot 7.62 out of a .308.
Click to expand...
The reason for this is that the chamber spec are different. (I will use the .308 as an example. Everything pertains to the .223 as well).
It is not that you cannot fire factory .308 Winchester in a 7.62X51, or that you cannot fire factory 7.62x51 in a .308 Winchester/Rem700, etc, because you can.
What matters is that you cannot fire reloaded cases (not that you are allowed to have them) fired from a 7.62x51 in a commercial rifle chambered for the .308 Winchester WITHOUT F/L resizing.
Specs for the .308 are
308 Winchester (SAAMI) Gauges
GO - 1.6300"
NOGO - 1.6340"
FIELD - 1.6380"

Specs for the 7.62x51 are
Shop (Military) Gauges
GO - 1.6350"
NOGO - 1.6405"
FIELD - 1.6455"

As you can see, the military chamber is sloppier to allow for dirt, mud, grease, other cr*p found in the field, and still be able to chamber and fire.
Because of this trying to chamber a round fired from the 7.62 and only re-sizing the neck would have the shoulder coming up before the bolt could close in a commercial rifle. In a semi-that would definitely cause stoppages and frustration.(but everyone knows that you ALWAYS F/L resize for semis)
However, if you F/L resize, then fire them, they will fireform to your chamber and then neck size til you drop! You'll be fine. Oh, one other thing, volume in military cases is normally less than commercial due to thicker brass. Not much but it can affect pressures at max commercial load data.
Enjoy!!
 
"...do you mean .311?..." DOH! Yes. Trying to type too fast. Friggin' key board doesn't type what I'm thinking.
"...the groove diameter to be .312..." That's the important measurement. The lands diameter is the nominal bore diameter. Your barrel is too big for .308" bullets. The gasses will zip past a jacketed bullet. Giving you poor accuracy.
Hornady makes a 150 grain .312" SP. They make a 174 grain RN that'd be fine out of a single shot too. Sierra makes a 174 grain .311" Matchking and several .311" hunting bullets. One thou won't matter.
"...why not to shoot 7.62 out of a .308..." It's an endless argument. Mostly on the Internet. The 7.62NATO case is a tiny bit different from a .308 Win. However, before there was an internet, lots of shooters used both interchangeably in both battle rifles and hunting rifles with no fuss. Ditto for a 5.56/.223.
For a 7.62 x 54R, the 7.62mm is the nominal bore diameter. That's the hole through the barrel measured across the lands. It's bore diameter is measured across the lands. So is a .303 British.
In North America, bullet diameters are measured and given across the grooves. The nominal bore diameter of a .308 Win is .300". So is a .30-06 and any other cartridge that uses a .308" bullet.
Don't even think about trying to figure out why a particular cartridge is called what it is. It'll give you brain damage. For example, a 7.5 x 55 Swiss uses a .308" bullet. And .308" doesn't convert to 7.62mm's. It converts to 7.82mm's. 7.5mm's does convert to .300".
 
rookie wildcat said:
Isn't this fun??!!:)
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i learned not to trust my big name gun shop catalogs, i always assumed that they listed all the bullet diameters in their component section, but alas, not for the .311 diameter:redface:

i will have to try out that slugging thing,and measure the rifling as well to see if the sierra 174 grn matchking will shoot or not.

hehe, a match bullet for my combloc semi-auto:D
 
rookie wildcat said:
Sierra makes 125's, 150's, and 180's. Anything you can load in a .303 will fire from a .311 bore 7.62x39mm. Heck, I have even loaded 220gr .308 and fired them nicely both sub and supersonic. Matching up a 180 to the SKS puts it right there with the .30-30 loaded with a 170 gr. Have fun.
Click to expand...
had to do some looking but I found old data (on a 5 1/4" floppy) Yes I still have a 386 that has my data on it. It is slow but it never seems to break down. However, I now think, since I had to look so hard and it was slow, it is time to put everything on my laptop.
7.62x39mm

Ballistics Table in Yards
Sierra 220gr RN .410 B.C.
Unique 4gr
Range (yards) Muzzle 50 100
Velocity (fps) 780 768 755
Energy (ft.-lb.) 297 288 279
Pressures didn't register as being worth the trouble..

Ballistics Table in Yards
Sierra RN ***180 gr., .378 B.C.
Hodgdon H335 25 gr
Range (yards) Muzzle 50 100
Velocity (fps) 1800 1696 1596
Energy (ft.-lb.) 1295 1149 1019
Pressure C.U.P. 29,000

As you can see, sufficient for bear defense or even close range hunting. Test done with an Oehler ballistics lab, including the gauge taped to the rifle action. I think it is fairly accurate. Wish we had a longer range as well. However, you can use that data to extrapolate further distances.
 
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