Comments about shooting .303 ammo through a .308 bore

[ireload2]

Not trying to stir the pot. The commenter used to work for Ruger and comments on some of the testing that he did along with observing the statistics on the resulting pressure.

http://www.castbulletassoc.org/forum...10&forum_id=65

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[Sentryduty]

Posting in case the link goes dead:

QUOTING USER "Ed Harris"
When I was with the company in the middle 1980s they made a small run of less than a hundred No.3 carbines chambered in .303 Brit. These guns had plain varnished birch stocks and dull matte finish for a Canadian distributor who sold them to Indians and eskimos. They had 20 inch normal .30 cal. barrels on them and shot really well with 180-grain CIL softpoints.

Last edited on Tue Apr 27th, 2010 08:35 am by Ed Harris

Actually Jeff, when I was at Ruger I had pressure barrels made with the standard .312 groove and also with .308 groove diameter and tested them extensively with a variety of UK, Cdn. and US .303 military and sporting ammunition.

Using the SAAMI and CIP dimensioned sporting chambers, NOT the sloppy WWII military "trench" chamber, the pressure rise with the tighter groove diameter did not appreciably exceed the sample pressure standard deviation, the difference was about +2,500-3,000 cup. While the reference ammunition used for the pressure test calibration was somewhat higher than normal, the differences observed were within permitted statistical limits. The corrected sample averages were in the upper range of Cdn. military standards and well within the design limits of the Ruger No. 1 and of sound No. 4 rifles which are properly set up.

My Cdn. Long Branch custom No. 4 has a hammer forged Heym barrel having the normal 7.62 NATO rifling form and dimensions, but was chambered with a .303 British pressure barrel reamer. It handles ordinary UK and Cdn. .303 Mk.VII ball and MkVIIIz ammunition just fine, as well as the Privi Paritsan with no hard bolt opening or high pressure signs. Reloading case life is also quite good. The rifle has about 3,500 rounds on it and headspace has been maintained, I haven't had to swap a bolt head.

In my handloads I use published data from the Speer No. 13 and normal Remington, Sierra or Speer .303 bullets and velocities agree with published data. Several friends had similar custom No.4s made on Long Branch or Savage actions about the same time and there have been no pleasant surprises.
Last edited on Thu Apr 29th, 2010 09:04 am by Ed Harris

Notable quote of the quote:

These guns had plain varnished birch stocks and dull matte finish for a Canadian distributor who sold them to Indians and eskimos.

I am not sure if the fellow is uninformed, or intentionally crass, but that is not a statement I would make on the internet with my name attached to it.

Now about the bore discussion, people have squeezed normal .311/.312 7.62x54R out of .308 bore Mosin Nagant (Sako barrels I think) rifles, however I lack the expertise to decide if this is safe or foolhardy, but it has been done.

[browningautorifle]

If I recall correctly though, .303 barrels can run from .308 to .318 at extreme...usually only to .311 though. I've shot .308 FMJ loaded in .303 cases and 220 gr soft point .308 bullets too. That was all from a #4 sporter. I think you could easily get away with the other way around. I've used bullets pulled from 7.62X39 in .308 as well. No ill effects...they weren't 180s though. And they were using their own powder charges, so it was light.

[Eaglelord17]

I am not sure if the fellow is uninformed, or intentionally crass, but that is not a statement I would make on the internet with my name attached to it.

You also have to remember that is how they were referred to until very recently. I suspect it is likely a older guy (makes sense if he was working in the middle 80s), and that is likely how they have always been referred to in his life. Not saying it is right or wrong, just that historically that is what the native populations were called (and technically according to the Indian Act, still what they are).

[newcastle]

I concur. Political correctness shouldn't rear its head in these places and unless there is clear evidence of ill intent we should assume the opposite.

[Bruce_in_Oz]

.308 bullets vs .311 bullets; a whole 0.003"

With a standard lead core and gilding metal jacket, being kicked up the backside by 40,000 + psi.........

I've seen several No.4s that have been re-barreled using .308" groove, 1:12 twist barrels and then chambered for "standard" (Mk7 ball compatible), .303, using a .299" pilot. All seem to work fine with Mil-spec ball and a wide variety of hand-loads. NOT intended for 1000yd bench-rest matches, such conversions are basically a "workaround" to deal with the dire shortage of "proper" .303 ammo in quality and quantity. It also allows the use of a HUGE range of .308" bullet types, as long as you don't want to shoot LONG heavy, (168gn VLD to 220gn+) types. If you do, simply use a 1:10" twist as per the original spec.

There is one of these "hybrid" rifles in my safe right now and it was "test-fired" with Mk7 ball to no obvious ill effect to the cartridge cases or to the rifle. Its normal diet is 155gn BJD / HBC .308 projectiles, though Sierra 155gn Palmas work well, too..

As specified on the factory drawings, MIL SPEC .303" rifle barrels can run out to .320" groove diameter and still pass gauging. BORE diameter tolerance is a LOT tighter.

[CINDERS]

All we need now is a backyarder getting the idea and putting a 303 reamer into a 308 bored barrel toddling off to the range with an unknown load with a not so "sound No.4" and not getting away with it.

Also whats gives with his statement

custom No.4s made on Long Branch or Savage actions about the same time and there have been no pleasant surprises.

where there unpleasant surprises for them. I do not own a lab nor the resources to try such a novelty may be a grand thing in theory but not for CINDERS as if he is saying it is getting to 2,000 - 3000 CUP above a normal round I will pass.

[Bindi2]

There are more than a few 7.62x39 rifles around with 308 barrels. I have a AIA 7.62x39 with a mini gun barrel from the factory. So do you use standard 7.62x39 ammo or is it only a reloading project using .308 projectiles .

[Sentryduty]

You also have to remember that is how they were referred to until very recently

Let me say I don't want to derail this any further, but I would like to be clear about my small comment. The issue I caution of is not the exact terminology of the (any) groups, they change very frequently and keeping up would be a job in itself. My point raises from the comment that the original author supposed the construction and sale of a particular product to a specific ethnic group, that is the dodgy bit of ground that I wouldn't cross. The rifle could be better described as for Canadian wilderness use, for example. Targeting a product to a specific ethnic group in your marketing has been seen in a negative light for a very long time.

As I said, I personally would not express myself, especially identifying as a employee or former employee of a company in that manner.

All good conversation though, just had to clear up my thoughts is all.

Shifting the topic back on rudder, with a .311 down a .308 bore, has anyone observed shedding of jackets or other projectile issues at either service or higher velocities? How does accuracy compare, is there any benefit to the tighter bore in that regard, or is it a complete wash?

[browningautorifle]

I've had no problems, jacket shedding or accuracy...or pressure issues like pierced or simple primers. As Cinders states though, I don't have a lab to test in so those are only thumbnail measures for pressure.