Ruger # 1 in .303 British

[1Hawkeye]

Does anyone know what the bore diameter is in a Ruger #1 in .303 British?
Did Ruger do it right or are they .308 diameter?

[Ballistics in Scotland]

My guess is that they did it right, but you never know, as they gave the Mini-16 a tight bore for the 7.62x39, and insisted that it was all right for all conventional cartridges. I'm sure if the .303 is a Ruger product, they won't have made it dangerous with commercial or surplus ammunition. You should be able to load .308 bullets and get good brass life with standard dies, if you buy the right expander button or reduce the original one by spinning in a drill between pieces of abrasive paper. Either way it should be a fine cartridge for the Ruger No. 1.

I actually did this with a .303 P14 Enfield, just for a bit of experimentation before rebarreling it as a .300H&H, for which I didn't think it worth buying .312 bullets. It gave miserable results with Nosler solid based boat-tails, but with thin jacketed flat based bullets was as good as anybody dare expect of an unpitted but frosted bore. That isn't really relevant to your case, but what is, is that I did get .308-bullet cartridges which tested out well for bullet concentricity.

[1Hawkeye]

That's why I'm asking a couple of friends have rugers a mini 30 & a single six convertible in .32-20 both of them have.308 bores. The #1 is going to be a cast bullet gun so I was wondering if I need a .309 expander ball.

[Jeff Michel]

I have a current Mini 30 (tactical) it slugged at .311. I am assuming that the convertible Ruger you were referring to was the "Buckeye" model Blackhawk? .32-20/32 H&R Mag? if so, mine slugged at .312. I do not have the .303 but I have one of the 7.62x39 in a No 1 and it's right at .310. The early bolt guns and Mini 30 were .308, I think that was changed in the early 90's to .310/.311. I can't speak to it, but I'd say the current No 1 in .303 would be on the money. Heck, I'd call them if your not sure/concerned. Probably the surest, fastest way.

[Outpost75]

I have a No.4 Long Branch Lee Enfield which was rebarrelled with a .308 groove diameter barrel and chambered in .303 British using a SAAMI-dimensioned pressure velocity barrel reamer which cuts a minimum chamber. I have had no hard extraction or pressure issues shooting factory .303 British ammo in it, including HXP Mk.VIIIz and MkVIIz. My most accurate handloads are with the .311" Sierra 174-grain Matchking using 42 grains of RL15, which approximates the velocity of factory ammo. My cast loads use the NOE version of #314299 and I size bullets .312 which fits the throat of the SAAMI chamber, using 30 grains of 4064, RL15 or Varget. No issues.


As FYI on Gunbroker there is a similar rifle built by the same gunsmith who did mine. I know the rifle and the owner.
You could not come close to duplicating this for the price he's asking: http://www.gunbroker.com/Auction/ViewItem.aspx?Item=553972669

[Frank46]

I seem to remember about the 303 Ruger is that instead of using tighter specs for their barrels they used different ones so you may end up shooting .312 bullets through a .314 dia barrel. Don't remember which spec or where they got their info but if they had done it right you would be shooting .312 bullets through .312 bores. There was a big stink about it at the time. Frank

[gandydancer]

Slug it man?? its easy enough to do and then you'll know..

[JeffinNZ]

See this from CBA forum:

http://www.castbulletassoc.org/forum/view_topic.php?id=5710&forum_id=65

Ed used to work for Ruger.

[Ballistics in Scotland]

That about clears it up, and except for a small and easily identified prior run to a special order from Canada, the bore dimensions are well within the range of normality. His findings on the effect on pressure of .303 bullets with the conventional .30 bore don't surprise me either. There is a record of accidents when 8x57 bullets were fired in .30-06 Springfield rifles, but that is a bigger diameter difference, and there was generally some other contributing factor.

[1Hawkeye]

I don't have the rifle yet or I would have slugged it. Thanks for the help I think I just got a new rifle.

[Ballistics in Scotland]

I can't see you going wrong, as long as it is still the way Ruger made it.

[Bill*B]

Ruger customer service is pretty responsive. If you email them and inquire what the nominal bore/groove diameter is for your rifle, they will tell you.