Bullit OVERSIZE

[1jonzmith]

Yes they make a 7.62x39 rifle that shoots .311 bullets well. That is because it HAS a .311 bore!


When I called Savage and spoke with their tech folks, they told me the Model 10 FCM Scout in 7.62x39 had a .308 bore. To be honest, I have not slugged my barrel to confirm or deny this.


Thank you Thomae,

You are at least the third person that has verified that about Savage and today I learned they have a cal adapter so it will shoot both rounds.

Please just stick a caliper into the muzzle (gently) and measure the groove and land diameter.

My Sierra rifle loading manual Fourth Edition, pp 385, says "rifles chambered for this round are readily available in two distinctly different bore sizes, 308 and the original 311.diameter. Reloading equip manufacturers recognized this and now supply their 7.62 X 39 dies with a expander ball for 308 and a separate one for 311."

This is the finale for me and I will order my chamber reamer for 7.62 X 39 with a 308 bore. Bet the barrel maker has a reamer on the shelf to handle it but I will do this more than once and I do have friends that will want to borrow it. Free bore and neck(unturned) diameter/clearance are now the questions to be answered. Reamer at Pac Tools always wants me to provide him with a unprimed round with the bullet of choice seated to the depth I want. S&B 123 grain SPBT gets the nod.

Thank you all. i will try to post a report on accuracy I get for the different diameter bullets. Not from the hospital, I hope. ??? ::) ;D

John

[thomae]

Yes they make a 7.62x39 rifle that shoots .311 bullets well. That is because it HAS a .311 bore!


When I called Savage and spoke with their tech folks, they told me the Model 10 FCM Scout in 7.62x39 had a .308 bore. To be honest, I have not slugged my barrel to confirm or deny this.


Thank you Thomae,

You are at least the third person that has verified that about Savage and today I learned they have a cal adapter so it will shoot both rounds.

Please just stick a caliper into the muzzle (gently) and measure the groove and land diameter.

My Sierra rifle loading manual Fourth Edition, pp 385, says "rifles chambered for this round are readily available in two distinctly different bore sizes, 308 and the original 311.diameter. Reloading equip manufacturers recognized this and now supply their 7.62 X 39 dies with a expander ball for 308 and a separate one for 311."

This is the finale for me and I will order my chamber reamer for 7.62 X 39 with a 308 bore. Bet the barrel maker has a reamer on the shelf to handle it but I will do this more than once and I do have friends that will want to borrow it. Free bore and neck(unturned) diameter/clearance are now the questions to be answered. Reamer at Pac Tools always wants me to provide him with a unprimed round with the bullet of choice seated to the depth I want. S&B 123 grain SPBT gets the nod.

Thank you all. i will try to post a report on accuracy I get for the different diameter bullets. Not from the hospital, I hope. ??? ::) ;D

John
I'd like to make sure that we are talking about the same thing here.
I have a Savage rifle chambered in 7.62mmx39mm Russian. I believe it has a bore diameter of 308/1000 of an inch. It is not chambered for the .308 Winchester round. When I get around to slugging the barrel with one of my .314 lead pistol bullets, I'll confirm the diameter.

I own a set of Lee dies for 7.62x39. They have two expander rods, one for a .308" bore the other for a .311" bore.

Adapters are commercially available to shoot 7.62x39 rounds out of rifles chambered in .308 Winchester.


You are at least the third person that has verified that about Savage and today I learned they have a cal adapter so it will shoot both rounds.
The above sentence is confusing. What I verified is that my rifle, chambered for 7.62mmx39mm Russian, has a bore diameter of .308 inches.
I do not understand what you mean by "both rounds."

Other data to consider:
The difference in chamber length length between 7.62x39 and .308 is about 12 mm or 1/2". The adapter takes up this space, but that's a long way to jump before hitting the lands and grooves. This may or may not affect the accuracy of rounds shot from a rifle with an adapter. Don't know, never tried it.

The two rounds have different rim diameters .308Winchester and 30-06 Springfield are .473", 7.62mmx39mm Russian is = .447".

Now, before this thread spins out into the weeds, I am going to back up and specifically address the OPs original question:
If I have a 308 barrel can I safely shoot 312 bullets? What about 309, 310 and 311? How would you expect the accuracy to be affected?
Thank you,
John
1. Background: Some people have been successfully shooting .311 bullets in a .308 bore (specifically in rifles chambered for the 7.62mmx39mm Russian cartridge.)
2. From his question, I know nothing about what rifle or cartridge 1jonzmith wishes to use to shoot .312 bullets through a .308 bore. I also don't know what kind of bullets he would use. I don't know anything about his level of expertise, knowledge of reloading, internal issues, and a whole bunch of other issues that might affect the safety of what he wishes to attempt. Therefore, (and I am not putting him down or casting aspersions in his direction), although there may be some situations where it would be reasonably safe to shoot a specific oversized bullet through a .308 bored rifle, I take the high road and recommend that he DOES NOT shoot oversize bullets through his bore.
3. ...So my answer to the OP about shooting .312" bullets through a .308" bore: I would not recommend it.
4. ...as to .309", .310" and .311" bullets? Not enough information, so I would not recommend it.
5. ...as to accuracy? I don't know. Accuracy depends on so many more factors than bore and projectile diameter.

Sorry this is a long post, but I want to be as clear and specific as I can.

[Eric in NC]

You have a quote attributed to me that I did not say.

[thomae]

Eric,
Thanks for bringing that to my attention. I went back and corrected my post.
Sorry about that. I had edited out the extra stuff and cut and pasted incorrectly.

[1jonzmith]

Thomae,

You wrote:
"Adapters are commercially available to shoot 7.62x39 rounds out of rifles chambered in .308 Winchester."

That's what I meant by "both rounds" . I was quoting you.

I think your sharing that the die set comes with a 308 and 311 expander die, and others verifying that, as well as the advertisement of the die mfrs., I think this is settled. And, as always, advice to stick with the precise calibre is prudent and valid.

Thank you for all the info and your superb posts.

John

[thomae]

You are quite welcome. That's what this forum is for.
:D
I just wanted to make sure I was clear as to what I was saying, and that I really understood what you were saying so that I didn't accidentally pass any bad information.

I hope you are having a good weekend.

[Eric in NC]

"Adapters are commercially available to shoot 7.62x39 rounds out of rifles chambered in .308 Winchester."



I will point out that the LONG free bore created by such an adapter serves to significantly reduce pressures. 1/2" or more of oversized bore with no rifling before the bullet gets to the lands.

Use several adapters - never played with that one but 32 H&R mag out of a 7.62x54R or 303 Brit is fun.

[1jonzmith]

Yes they make a 7.62x39 rifle that shoots .311 bullets well. That is because it HAS a .311 bore!


Eric,

Where did you get your information?

Thanks,

John

[1jonzmith]

The gun I will be using is a CZ VZ 58. It is a AK like clone but the innards are far superior and it uses a completely different locking mechanism. It locks up like a Walther P38 or that famous German gun MG 42. The 42 is billed as the best Machine gun ever created and nobody makes it anymore so manufacturer pressure isn't a factor. The Walther mechanism is billed as an extremely "robust" mechanism. I only know for sure that they are really different in design....and that my Walther P38 had been ruined by a previous owner and his file rendered the "out of battery safety" inoperative. It blew up in my hand when it fired out of battery on one of my "semi" hot loads. I gathered up the pieces that were thrown 30 feet, reassembled the gun, and continued shooting for the rest of the day. Trust me when I say that every shot was prefixed with a careful visual of the bolt being in battery. That proves not a single thing. View the CZ VZ 58 on the Czeck Point site and the film is awesome.

The 58 comes with a .312 barrel. It is something less than pin point in it's accuracy. I own many Czeck weapons and all are standout examples of robust accuracy. I want the 58 to fall into that category but the facts are that a 309 bullet thru a 312 barrel yields 4-6 inch groups ...at best. That is acceptable Assault Rifle accuracy and typical of the AKs. The Czecks did this so their rifle would shoot "all" Soviet bloc 7.62 X 39 ammo and the standard there adds new definition to the term "loose". The vast majority of the stuff is held to the 309 spec but there simply is no telling what the Bulgarian and other factories might put out. The Czecks were forced to use the 7.62 ammo and the Soviets, ever resentful of the Czecks probably defined the "bore" dimension of the rifle as well as the cartridge profile. Putting a scope on this gun, and they make them, would be like putting rouge on a pig.

Soooooooo to satisfy my curiosity I bought a 58 "kit" and a new receiver and a bull barrel 308 and a 7.62 reamer in 308. My reamer guy says he does many of the reamers and that they shoot like a 30 CAL BR. I am not trying to make a BR rifle from a Assault Rifle but I expect 1 or maybe 2 MOA from the gun. Even at that I could justify having a scope or red dot on that bad girl. It's a toy folks, plain and simple, like all my guns including the one next to my bed. My heart burn is leaving behind, and at 70 that event must be getting close, a "Booby Trap" for the hapless enthusiast that comes to own my unique creation one day. At this point I am concluding that a 312 will go down a 308 barrel with at least marginal safety.

My problem at this point is the strength of the receiver. Complicating that is the fact that mine is made in the US and is not genuine Czeck. I can't see any way around this than to borrow a strain gauge and check for pressure in each calibre "case".

While my Bull barrel will be profiled it will be a lot thicker and a little longer than the original. In short, it will no longer meet the definition of an Assault Rifle and most certainly not that of a 58 as it will be a couple pound heavier. But I am not building a 58 clone so unique doesn't matter except that it is desirable. This will take a lot of time so don't look for a "final report" any time soon. So far I have all the parts except the chamber bore and that is on order so I am committed.

Thanks for all your help,

John