.311 bullets in .308 bore?

[huntsman]

I am wondering about the ramifications of shooting .311 bullets of the 7.62x39 cartridge down a rifle with a .308 caliber bore. The owner of this rifle says factory ammo shoots fine, but I wonder if there may be more issues here that just a few rounds that fired "okay". My thoughts are that the bullets will probably sqeeze down the barrel, but that pressure will go up and velocity will suffer. Also I suspect this wouldn't be good for the bore after a while, either. Any thoughts?

[Mikey]

huntsman, I would agree with your concerns however, when Ruger first brought out the Mini-30 to fire that round, it came with a .308 bore, not the .311 the round normally takes.  I have heard that the Mini-30, and the couple I've shot, were capable of decent accuracy but I can't qualify that over long term use.

I would think that the continued use of larger than bore bullets would eventually take a toll on the rifling and would cost you accuracy but, I'm sure not the expert on this one.  Maybe some of the fellas who own one could help more.  Mikey.

[Robert]

Look at load data for 8mm Mausers....the older ones are .318 bore and most US ammo is loaded with .323 bullets but with lighter loads.  The modern .323 barrels can handle a very nice load that is right up there with .308 and almost 30-06 velocities.

[Robert]

I have heard just the opposite about the mini 30's....all I have ever heard is that they are HORRIBLE for accuracy.  On the other hand....what I HAVE heard is that people have acctually won competion with .308 caliber bullets in .311 bore.

[S.S.]

Match the bullet diameter to the bore or you are asking
for either pressure problems (Over sized bullets)
or poor accuracy (Under sized bullets).
The three hundredths of an inch does not sound like
a lot between the .308 an .311.  But I would not risk the
pressure build-up of using a .311 in a .308 bore.
And a .308 bullet in a .323 bore? I don't see how the projectile
even touched the rifling! I would not even attempt that.

[1911crazy]

I did a search for "reloading 7.62x39"  and here's what came up go to:

http://www.reloadbench.com/cartidges/762r.html

I remember looking into doing this for my sks and i found this info at MidwayUSA  in the rifle bullet section in the 303/7.7jap/7.62x39  .310 to .312 section there is Hornady bullets for reloading the 7.62x39 at .310 dia.

So one must becareful which gun your shooting Ruger ".308"  and SKS/AK47  ".310"   I guess if you have a newer bolt action rifle it would be 308 too if its made here.  Now i'm not sure what the imported bolt action rifles would be so slugging the bore may have to be done.  I wouldn't play around with the bore diameters with the sks/ak47 too because of the chrome lining, i wouldn't want to damage it.
                                                                           BigBill

[jgalar]

I don't own the Ruger, but to my understanding it has a nominal .310 bore. The idea was to have a bore somewhat in the middle so it could shoot .308 to .311-.312 bullets. Does any manufacturer actually load commercial rounds with .308 bullets? I am not aware of any.  I doubt Ruger, or any other gun maker, would put out a rifle that required a handloaded cartridge. The only way to determine is to slug the barrel.

[1911crazy]

At the reloadbench site it says the ruger is ".308" groove diameter but its made to handle both diameter bullets.  I'm guessing the throat is funneled so anything close work I guess.  

Bullet diameters of the ammo i have;

1. russian barnaul  123gr. HP   .308
2. russian XXXXX   123gr. HP   .307  (plain brown box no manufacturer)
3. wolf                   122gr. HP   .308
4. chinese norinco            FMJ   .309  (no bullet weight on box)
5. chinese military            FMJ   .307  (on 10rd strippers copper washed)
6. german              .123  FMJ    .310  
7. russian ulyanovsk machinery plant 124gr. HP  .311

This is why some ammo works better than others in accuracy.
Now i see why my sks is so accurate with the chinese nornico ammo.  The bullet diameters are all over the place.                           BigBill

Hey S.Sumner those 30-06 bullets sure went out of my 6,5 JAP Rifle ok till one got stuck in the bore for some reason?? Kidding but it was said right? Scary??  I guess we need armor plating between the shooting benches at the public range now.  If the shooter uses the wrong bullets the gun blows up to the sides right?  I'm talking a big difference in size not just .003 thousands in size.  The 7.62 is a lot different than 6.5?  I can't believe the first one went down the pipe and out?  Thats almost 1mm difference,  were talking .040"  thats 40 thousands!!!!!!  I wouldn't try it but i would sure like to see it done again.

[huntsman]

Intersting note on the different bullet diameters, BB. I had no idea they might be all different, but I guess it makes sense because of this whole issue. Looks like for most of the ammo, the .308 bore is actually better suited to the ammo than a .311 bore would be.

[1911crazy]

Most of the ammo is good for a 308 bore.  Interesting?  I never gave it any thought all the ammo would be so different in size.  I would surely check the imported ammo before shooting it now if i had a ruger "308 bore" to be safe.  As some of this stuff i have is older the newer lot may change in size again.  But hornady makes the ".310" diameter for those who want to reload for their sks/ak.                                         BigBill

Now I wonder what tolerances can a bore take?   Whats too big and whats too small for the 308 bore?  Don't for get .002 is the hair thickness on your head.  While it doesn't seem like much but just .002 difference in a diameter can be a big change in pressure like S.Sumner said.  I would think in my sks/ak the .311 would be max in size.  Now i wonder how accurate the .307 diameter is too.  My paratrooper sks w/16" barrel with the chinese norinco .309 dia. ammo is shooting 1 1/2" groups at 100yds benchresting it and thats down solid on the bench with no movement.

Now they say an AK47 isn't as accurate as an SKS that could be a bore size to bullet diameter  problem too.  I think any gun that shoots close to 2" groups at 100yds is excellent "acceptable" accuracy.

For you EX Military guys how far did you shoot at the range(distance) and what kind of groups are acceptable?  Is printing in the black anywhere on a people target good enough?  Or are you looking for tight groups too.

[jgalar]

I just pulled some bullets from some of the foreign steel cased ammo that I have and got .310 for the old Chinese and Russian Wolf and .312 for another Russian unlabeled box. One thing that is consistant with chinese and old iron curtain products is their inconsistancy. :-)

[1911crazy]

I just pulled some bullets from some of the foreign steel cased ammo that I have and got .310 for the old Chinese and Russian Wolf and .312 for another Russian unlabeled box. One thing that is consistant with chinese and old iron curtain products is their inconsistancy. :-)

I'll bet the 7,62x54 ammo is the same way too??  Its all different diameters.  I did buy some 7.62x54 stuff that was suppose to be as good a quality as sniper stuff a while back.                     BigBill

[S.S.]

Hey BigBill,
  The kind of accuracy that was expected Kinda'
Depended on what branch of the military you were in.
For some of us, OK accuracy was not good enough.
I have worked with (not enlisted in) just about every branch
of the military except the Coast Guard, And Most of the folks
I worked with were very well trained in the use of their respective
weapons within 300 meters or so.
I was working with a Sniper from a Georgia Unit once,
and I have never seen his Equal for accuracy. He used a modified
M-14 and I never once saw him miss his target. He got a lot of
practice in Beiruit. "DINGING RAGHEADS" was what he
called it . I watched a SNIPER SHOOTING CONTEST on the History
Channel a few months back, and all of those shooters looked
like amateurs compared to this guy. I sometimes
wonder what happened to him?

[1911crazy]

Hey BigBill,
  The kind of accuracy that was expected Kinda'
Depended on what branch of the military you were in.
For some of us, OK accuracy was not good enough.
I have worked with (not enlisted in) just about every branch
of the military except the Coast Guard, And Most of the folks
I worked with were very well trained in the use of their respective
weapons within 300 meters or so.
I was working with a Sniper from a Georgia Unit once,
and I have never seen his Equal for accuracy. He used a modified
M-14 and I never once saw him miss his target. He got a lot of
practice in Beiruit. "DINGING RAGHEADS" was what he
called it . I watched a SNIPER SHOOTING CONTEST on the History
Channel a few months back, and all of those shooters looked
like amateurs compared to this guy. I sometimes
wonder what happened to him?

S.Sumner  I seen the show on the History Channel n "Snipers"  and they had a few shows running that day on Snipers they also had the Women Snipers of Russia too with excellent pictures of their SVT-40's and 91/30 sniper rifles too.  I was lucky to have an empty VCR tape and i pushed the record button and let it roll.  The civil war snipers were very impressive too.  I guess it comes down to how well you know your rifle too.  Hey its about "ONE SHOT ONE KILL"  and it can really demoralize the enemy too in the process.  I seen another show on the history channel too about the "US" snipers and how they build there own rifles.  There was an article about the Canadian Sniper team making a shot in afganistan at 2500 meters with a Barret 50cal.  they shot thru a piece of  tin roofing the bad guy was hiding behind taking him out.  I guess he had our guys pinned down for sometime while the sniper team moved into position.  I can't imagine that 50cal. 700gr bullet in a rifle.   Thats "GOD" right?  He sure must be a welcome sight when your in trouble.   BigBill

[Robert]

I was comparing the .318 and .323 for the 8's....and the .308 and .312.  What I meant to say is that people win matches with .308 in .311 bores...not .323.  Sorry.

[Robert357]

I am wondering about the ramifications of shooting .311 bullets of the 7.62x39 cartridge down a rifle with a .308 caliber bore. .....My thoughts are that the bullets will probably sqeeze down the barrel, but that pressure will go up and velocity will suffer. Also I suspect this wouldn't be good for the bore after a while, either. Any thoughts?

You understand things well.  I have a 32 ACP (0.312) Adapter to shoot inside a 30-06.  It works even with an light powered pistol cartridge.  I wouldn't do it much for fear of accelerating barrel wear and I would do it only with lead bullets in the 32 ACP.

As to the 7.62x39 that is really suppose to be a 0.310 cartridge.  I have measured several an all mine come out between 0.310 and 0.311.  I have also pulled a number of 7.62x54R bullets and they measure the same, although the .311 part (if present) is usually just a small ring near the base of the bullet, with the rest being .310.

The Ruger Mini-30 is suppose to have a .308 bore. My concerns over using mil-surp 7.62x39 ammo in a Mini-30 would be corrosion and barrel wear, especially if I had purchased some of those copper jacketed steel bullets that are out there, as there would not be much to "squish" down in the bullet to create grooves in the bullet from the rifling of the .308 Diameter bore.  

If that were to occurr, I would expect that your rifle would be copper fouled real quick.

Lots of good advice.   Good Luck

[Peddler Parsons]

I have both a 44 and a 91-30  7.62x54 and both mike at 310. My understanding of the issue is that they overbored them so they would not shoot the bore out so fast.  I have loaded 311 and have very good groups 1" at 100yds with the 91-30 better than the 308 bullet the 44 being shorter has more kick so I only get 2 1/2 to 3" groups with it.

[Robert]

I was told by an old gunsmith that used to deal with these, and is somewhat of a military historian....the 7.62 ammo was also used in a full-auto weapon that used the slightly larger ammo to increase operating pressure.  The bores in the M-44 were opened up to be able to use the same ammo.