8mm in 30-06

[Grimstod]

Now before you think I am recommending you do this stop there. I think putting a 8mm bullet, that measures .323 into a bore that on the worn out side might be almost as big as 310, is totally stupid.
So here is my question. Just how oversized or tight can a bullet be? I would think that .001 might be ok but watch out for pressure signs. What about 0.002 or even 0.003ths oversized? I have friends that have rebareld their Mosins with 308 barrels and chambered them with 7.62x54r. They say that its ok. I don't think it is and I don't really have any evidence to prove it. Can you guys help me out.

Here is a photo of one experience of someone that put Russian Match surplus that measured 0.3095 into a 308 boar and it was blowing primers. He put a forcing koan into the freeboard and is back to shooting surplus through it.

 

[KMart]

Here is a thread on another site that did just that. They made bullets in .001 incriments from .300 to .315 and shot them.
Sounds a whole lot crazy, but to some degree, Saeed is.

http://forums.accuratereloading.com/eve/forums/a/tpc/f/3621043/m/8261079471

 

[jonbearman]

You might take into consideration that you have a very loose firing pin to the hole in the bolt head.I would have it bushed to be safe.

 

[Grimstod]

Thank you for the link Kmart. I read it all the way through. I noticed one thing and some one points this out in the end of the thread. The body of his bullets were never made big enough to touch the grooves of his rifle. Only the bands on the bullet were enlarged. Would this affect the test. Those bands on the bullet are rather thin and I would thing they would just get shaved off?

His revelation about how shooting a smaller bullets was also very interesting. To think he did not see any key holing till he hit .302 and he says that at .305 which is 3 thousandths smaller he saw no degradation in performance except for a small drop in muzzle velocity.

jon what does bushed mean? That is a new term for me. The bullets in the photo (first post) were shot in someone else's gun and not mine.

 

[bheadboy]

FWIW, I remember some decades ago reading and article where Colt pistols were discussed, in particular the 357m. as it was discovered by the magazine writer Colt in that time period of the 1930-1940's used 9mm barrels in a lot of their 357m pistols.

The point of the article was the accuracy would not equal the s&w 357m but it was otherwise ok. I had at that time a Colt which I slugged and found it to e 9mm .355. sold it and got a Smith.


Bob

 

[johnu]

I have a Tikka factory chambered in .308 that I have shot Lapua D-46 (nominally .309) from. Was assured by posters here that firing .309 projectiles from a .308 bore was not a problem, but I was seeing some pressure signs at somewhat moderate loads of Varget and a .01 jump. Could have been due to: 1) the profile of the D-46, which has a long bearing surface, 2) the barrel being a bit tighter than .308 (should slug it), 3) the Tikka having a short throat (need to do a chamber cast), 4) a tight neck re certain brass (Lapua) and a .309 projectile, 5) a combination of two or more of those.

BTW, it shoots 155g Scenars incredibly well.

John

 

[Grimstod]

I agree with you johnu. I now believe shooting a bullet that is a 0.001th oversized alone won't be the end of your gun but rather a combination of all five things you listed might be a problem.

Now I know that this product is intended for cast bullets but I have noted on other forums people say they use them with jacketed bullets with limited success. Most people say that you can't really size down a bullet with it more then .005ths or you get jacket separation or spring back because the brass tends to spring back to its originally size but the lead core does not.
http://leeprecision.com/bullet-casting/lube-and-sizing-kit/

Any thoughts?
Is pushing a bullet that .005th oversized going to make you bullet fly apart if you have a fast twist barrel?
Could the bullet completely separate from its jacket if you exceed .005ths?

 

[bigedp51]

In 2009 the British NRA issued a warning about custom tight bore .308/7.62 rifles used in competition. The British changed from 144 grain .3075 diameter bullets to 155 grain .3083 bullets in their military ammunition.

The new ammunition raised chamber pressure to far in excess of reasonable pressures in the tight bore custom barrels designed for the .3075 bullets. These barrels were banned from competition due to the dangerous pressures generated and all barrels were to be inspected and gauged before allowed on the firing line in national competition. I can't find the bore data but these tight bore rifles were approximately .3065 or .001 smaller than the .3075 bullets. Which made these custom barrels .0018 smaller than the new bullet diameter of .3083.

 

[Grimstod]

Thanks Bigedp this has opened up a hole new realm of spec knowledge for me. I did some searching based on your info and found a lot of articles to prove your right.

Here is an article by a british Magazine. Go to the 67th page. I skipped a few sections but they do mention that boars that were tight often caused pressure issues with later date ammo that was .3083 instead of the relier .3075 that you mentioned.
This is the hole magazine:
http://www.airguns.bg/files/akraba/TS/2009-11.pdf
This link has just that article in it that is relevant:
http://storage.dynamic-arms.com/t-class/forum/HANDLOADING_THE_.308_WIN_Laurie_Holland.pdf

 

[finnaddict]

Now before you think I am recommending you do this stop there. I think putting a 8mm bullet, that measures .323 into a bore that on the worn out side might be almost as big as 310, is totally stupid.
So here is my question. Just how oversized or tight can a bullet be? I would think that .001 might be ok but watch out for pressure signs. What about 0.002 or even 0.003ths oversized? I have friends that have rebareld their Mosins with 308 barrels and chambered them with 7.62x54r. They say that its ok. I don't think it is and I don't really have any evidence to prove it. Can you guys help me out.

Here is a photo of one experience of someone that put Russian Match surplus that measured 0.3095 into a 308 boar and it was blowing primers. He put a forcing koan into the freeboard and is back to shooting surplus through it.

That is surplus ammunition you have pictured and it is typically HOT from the get go. The primers can pop often even if used in the correct bore size not to mention splitting in the necks and case bodies. Storage and production year also has something to do with it. It is possible to use slightly larger projectiles however to overcome the pressure issue the throat should be widened and extended. This is how Finland solved the issue of using Soviet .310 bullets in their .308 bored rifles. Hence the "D" mark commonly found on Finn surplus rifles. I used Hornady .312 in a .310 bore to improve accuracy and it worked with no pressure issues. I only decreased the charge and worked it back up. I would use extreme caution if the ammunition you use is STEEL CORED. If oversized the rifling will dig thru the bullets jacket down to the steel core and you will have steel on steel.

What is the head stamp on those cases? 188? What is the projectile type?

 

[Grimstod]

Finnaddict its All brass berdan primed 180gr match Russian ammo. Comes in a blue box. Like the one next to this gun.

If your getting split necks or shoulders its probably steel cases with copper wash. As they age they get brittle even though they were annealed 40 years ago. hence the water line on them. My surplus will split in my shot out mosins cause the chamber is eroded and probably larger then it should be. With Smyert Mk2 (Shown above) it has virtually a new bore and chamber that was never fired so it never splits any cases.
I have never had a primer blow out on a mosin with proper boar diameter. But I have only shot about 400 rounds of various types of surplus. The Bulgarian stuff tends to be better quality (sorry I am getting off topic) but after pulling a bunch I found that even though the bulgarian shoots better the Russian surplus steel case 147gr was more consistently charged with only about 1.5gr +/-

I have some of this stuff and they are loaded rather hot. Most cases come out with primer flow and they push a 200gr bullet at about 2400fps in a 26in barrel. Haven't cronied them in a unmodified mosin yet.

This stuff is SUPPER consistent. Pulled a bunch and they are within .3grains. Both bullet weight and powder charge. The brass looks really good and maybe (If I ever get time and we have another ammo shortage) I will try to reload these.

Sorry, back on topic. Seams like any time you go tighter you will have greater pressure. If you have ever tried any of the machine gun 7.62x54r that is loaded REALLY HOT, shooting that through a finn with a tighter boar might be seriously dangerous.
Check this out. Especially the second shot! Smoke comes out the action! He is shooting PPU 311 through a 3095 bore.
[youtube]http://www.youtube.com/watch?v=Rz9UbVUzWGo[/youtube]

Just another reason to be very carful when shooting tight bullets.

 

[pdog2225]

A little story along the thread lines.
About 3yrs ago I was at the range and a fellow shooter sat down next to me. He had a mauser 98, 8mm, with ball ammo. And his other rifle was a springfield 03-A3 in 30-06. One of his shots sounded really loud so I looked over at the empty case and commented that I had never seen a case with a neck that short. He had fired a 8mm round in his 30-06! He said it really kicked, but he actually hit his target at 100yds. Needless to say he removed one rifle and its ammo from his bench. pdog2225

 

[Grimstod]

So he did it by mistake?

I have heard of this happening before. The. 8mm is shorter then a 30-06. Think it has about the same base size so it would fit in the chamber. But I think I would not do it for $$$$ :-[ call me chicken.