Oversized SMLE

[mdi]

I have a little experience slugging barrels having done most of my guns (6 handguns and 4 rifles) but I'm getting odd results from my latest project. I have a Lee Enfield No. 4 Mk I* Savage, mfg. 1942, with 2 grove barrel. I slugged it twice and got measurements of .318"+ groove and .303" or so bore diameter. The .318" is what has me wondering; I've read of a lot of bbls slugging .312"-.314" (or mebbe .315") but I've not heard of a groove diameter that large. .318" for a .303 British barrel. Any thoughts? Any experience with .303 barrels slugging this large?

Thanks...

[junkbug]

That is not un-heard of, especially for a 2 groove. 2 grooves have very narrow grooves, the lands displace a lot of bullet lead, or copper jacket.

PS: as you measured, the bore, or lands, are right on the money. In European practice, the bore diameter is much more important than groove diameter.

[jonk]

Make a chamber cast, and/or see if a .320ish bullet will chamber in a fired case. PM me if you want me to send one sized to .319...

I've found in my similarly oversized enfield that a .319 225 gr RN will shoot as well as I can hold the gun. I also have an oversized chamber, taken care of with a rubber washer around the base of the case.

[PAT303]

A mate of mine has a similar rifle and he shoots 32/40 cast boolits at .320 through it with good results. Pat

[303Guy]

My two-groove No4 has bore/groove dimensions like yours with a bore of .303 and groove at .318. It shoots .310 bullets very well indeed. Cast boolits not so much. The problem is the throat which is a taper from throat entry at around .319 down to bore diameter with a 1.5 degree taper (3 degree included angle - or is it 3 degrees per side?) My other two-groove has the same throat arrangement and similar bore/groove dimensions. The throat squeezes the boolit down so much it forms drag edges on the base if sized to groove diameter, even with a gas check. The boolit base can be shaped to overcome this but the bore is actually rust 'textured' which means it's rough enough to cut into the driving face of the lands. I haven't tried the other two-groove which is mint.

[JeffinNZ]

That's not over sized for a two groove. Just the upper end. My .303 Pygmy has a .317 two groove barrel and shoots rather well with .3165 boolits. You could paper patch for it.

[mdi]

Lot to think about. I ordered some 190 gr. cast bullets at .321" diameter. I'll see if I can find/modify something to knock/swage another .001"-.002" off the diameter. I'll stuff one in a case and see if it fits the chamber. Largest jacketed bullet I can find so far (for my use in the .303) is .314", but I'll keep looking...

[303Guy]

Aah .... that pygmy. I didn't realize it was a two-groove.

I have a five groove with a bore something like .306~.307. It's destined to be cast boolit gun once I've polished all the rust out the bore. It takes a boolit that fits an unsized neck. What could be better? It only bears on the outer locking lug so that makes it perfect for low pressure cast loads.

[Jack Stanley]

You are not alone ..............The two groove rifles I've seen go from .316" to .317" and a number one mk three I had once went at .318" and would accept .319" without complaining .

Jack

[303Guy]

I've said before that my two-groove with its .318 groove diameter shoots .310 bullets just fine. The throat is just right for that bullet. I'm wondering just how far one can take the 'undersize' bullet. Now with cast boolits that are undersize, surely if the boolit is being supported by the rifling and sealed by a wad it should shoot fine?

[Outpost75]

That is what they are.

[Multigunner]

.318 is the maximum acceptable major bore diameter for all types of military .303 barrels, whether two groove or five groove.
A Savage two groove with over size major usually seals to FMJ bullets better than a five groove with the same size major. The broad lands of the two groove swage the bullet into the narrow grooves.
Largest Savage two groove bore I've miked was .316. Mine has a .314 and is pretty accurate.

Early SMLE MkI rifles designed for the MkVI cartridge had a reverse taper lapped bore. These can be very much oversized at the muzzle, as much as .321.
They reverse tapered the from about mid point bore to reduce bullet friction so the MkVI bullet from the shorter SMLE barrel would have the same velocity as it would from the longer LE barrel.
They found this was not very practical in the long run. Most were later re-barreled.

[Me not you]

I have a Finnish M91 Moisin-Nagant with a 0.315 groove diameter. I purchased an NOE 316299 mould. Casting with WW, water-dropping out of the mould and sizing to 0.315 , I got pretty good accuracy at around 2000 fps (32" barrel) over Accurate 5744 with no sign of leading. Cleaning involves one patch with Break-Free. I've always been pretty frugal (cheap) , but I wouldn't hesitate to buy another NOE mould. It's a 5-cavity, and I ran off about 30 pounds of keeper boolits in an afternoon. It's already paid for itself.
For an oversize bore, I'd load the largest boolit that will still slide into the neck of a fired cartridge case. 0.315 is the largest for my M91.

[mdi]

I've said before that my two-groove with its .318 groove diameter shoots .310 bullets just fine. The throat is just right for that bullet. I'm wondering just how far one can take the 'undersize' bullet. Now with cast boolits that are undersize, surely if the boolit is being supported by the rifling and sealed by a wad it should shoot fine?

Is that .310" bullet jacketed or cast?

[Larry Gibson]

Very easy to size down a .323470 to .320 or .321 if that diameter fits up into the throat of the oversize .303s. It has on a couple I've tried. That Loverin style bullet is an excellent shooter in such.

Larry Gibson

[303Guy]

Is that .310" bullet jacketed or cast?

That's jacketed.

I read an article many years ago about making a 270 into a 'magnum'. What the fellow did was to use a barrel with a groove diameter, the idea being that gas escape would lower pressure thus enabling a heavier charge to be used for higher velocity. As I recall the gain wasn't all that much, maybe 100~150 fps. I would imagine a heavier charge of slower powder would be required for such gains. No pressure measuring was done, just visual estimation.

On pressure/bullet size, just how much does bullet (jacketed) size actually effect pressure? I once tried to fire-lap a bore with a boolit rolled in abrasive which when fired locked into the neck which then tore off and became part of the boolit. The pressure was higher than it would normally have been but not excessive by any means.