I have some BSA Martini target Rifles with good sights and long barrels that would make excellent small game Rifles except for the weight. I would like to have someone bore out the barrels to a very large bore except for leaving about 8 inches of rifling at the Breech end, then crown the muzzle at the end of the 8 inches. At 8" the barrel diameter is .900" and .750" at the muzzle. What barrel wall thickness could be achieved at the bored out section? Can someone suggest a gunsmith? I believe that Harry Pope used to make 8" barrels with a heavy extension because he found that about 8" of barrels was most accurate for 22s and the rest was weight. It might be easier to cut the barrel, thread it, bore out the rest of the barrel and reattach with a permanent pin to meet ATF rules, but I'd rather have it bored out if possible. Comments?

When re-lining shot out or pitted barrels on .22 Martini rifles it was usual to use in England a reamer or borer the same diameter as would remove the rifling from a .303 barrel and clean it up for re-lining as a .22.

So I'd reckon about .315" or so. So any gunsmith that re-lines .22LR rifles ought to be able to do the job.

Having said that I know from experience of these liners that you won't loose much weight at all as, of course .22" of what you are removing is just a hole!

So I'm guessing you want a wider hole? In wich case the easier answer might be to turn down the outside of your stub beyond the breech and fit an outside sleeve?

I don't know if that is lawful in the USA. Personally if you chop to the American 18.5" length your hunting Martini would be "handy" enough surely? And you get consistent powder burn.

US minimum rifle barrel is 16 inches. Not 18.5. 18 for shotguns.
Easiest way would be to weld on a sleeve, onto the 8 inch barrel, instead of boring it. Although that could be done too, by anyone with a lathe. Min wall thickness? Just enough to keep from denting; look at shotgun barrels; quite thin.

I would think you would have a hard time getting a decent crown down in the hollowed out portion. And to ream a bore properly, you need a piloted drill and that will mess up the last 1/2" of your barrel badly. I suppose you could get a floating pilot made but that's not something you see on a drill made for relining so it would have to be custom made and it would be expensive. The only justification I can see for such a plan would be to make an integral suppressor, and even then there are better ways of doing that.

Those Martinis are target rifles and as such have overly long and heavy barrels. Why not cut off 6" or so and have the rest recontoured and/or fluted? Or just rebarrel, unless the original bore is perfect. A 22 mag or similar would be far more interesting anyway.

The 310 versions are much handier.

Thanks DPCD for the correction regarding barrel length. I'd most certainly now say that the OP could cut off to that length plus "a bit extra to be unarguably legal" and have his "handy" hunting Martini.

Why would one need a crown when the when the whole bored out section would act as one.

The bore is perfect, but it might be easier to bore out the barrel so that the wall thickness is about .025 at the muzzle, then install an 8" long liner. I have some nifty rook rifles with long thin barrels, and one original Cadet. That's what got me thinking about converting a 12/15 to make a lighter gun but keeping the long sight radius. I know that I could simply cut off the barrel to 16-1/4" and use a scope, but I have a scoped Martini already.

The crown is essential to a smooth and wobble-free separation of bullet from the confines of the barrel. It has to be perfectly concentric with the bore. I suppose you could use a custom piloted tool on a custom extension to get a decent crown, but to get the best result you need access to the crown set up in a 4 jaw on a lathe.

Liners come in standard diameters, 22s are usually 5/16". So to fill a bigger hole you would need to make a custom liner.

Thinking outside box, an aluminum barrel with a steel liner would be quite light. Or a Dan Wesson type arrangement with a hollow tube, full length skinny liner in tension. Or you could look into getting a carbon fiber barrel, these are commercially available.

Why not cut the barrel down to 16.5" and crown it. Then thread the muzzle and take a piece of thick wall tubing and turn it down to the same outside diameter as the section of the barrel which was removed and thread it correspondingly to mate with the thread on the barrel. Fit the front sight to the end of the tube and blue if desired. The barrel extension could be removed for cleaning.

Small bore shooters have been using "extension tubes" for years to increase the radius of their iron sights

There was a study done on Rimfire Central over 15 years ago. It showed with standard velocity lead lubed ammunition, the velocity increases were significant out to 18" and then smaller increases up to about 26-30 inches or so where after that they started losing velocity.

The also did testing with high velocity bullets and plated bullets also if I remember correctly. You may be able to search their site for it but I bought an 18" match barrel because of that, so that number sticks in my head.

quote:

posted document.write('<nobr>'+ myTimeZone('Mon, 21 Oct 2019 17:14:12 GMT-0700', '22 October 2019 05:14')+'</nobr>');22 October 2019 05:1422 October 2019 05:14Hide PostWhy would one need a crown when the when the whole bored out section would act as one.

Quite possibly the question has been asked by someone who does NOT understand the term "Crown".

perhaps not.

Somewhat off on a tangent to the original question but may well still be of import.
What affect will all those gases in the tube section of the "barrel" have on the bullet.

Seems like they should/could have some effect.

quote:

perhaps not.

I would be interested to have someone explain how the bored out section could function as a crown.

quote:

Originally posted by TCLouis:
Somewhat off on a tangent to the original question but may well still be of import.
What affect will all those gases in the tube section of the "barrel" have on the bullet.

Seems like they should/could have some effect.

None or so little you well not see an effect.

Think of bloop tubes on target rifles.

I have use them to reduce the sound signatures and have not seen any effect.

Not quite the same issue, but similar. I bought a Remington 521-T barrel on ebay for a 511 receiver. It turned out to have unacceptable corrosion in the last 8 or so inches of the 25-inch barrel. After cutting off 6 inches, I back-bored another 2 inches of so with a 7/16 inch drill with the barrel clamped in a collet on a South Bend Heavy 10. That would make its crown the same angle as the drill bit, back inside the barrel. It is reasonably accurate, cleaning it is interesting.

The majority of the mass in the barrel is in the outer thickness, not in the middle. Boring out the middle isn't going to make a huge difference in weight. I do wonder about the stiffness of a barrel and harmonic vibrations with what amounts to a hollow tuning section at the end, also the uniformity of the remaining bore. The 521-T barrel is straight, not tapered like the 511, maybe the the bore is more uniform from breech to muzzle. In Bill Calfree's book, he mentions some experimenting with the inside diameter of tuners, the choice of a 7/16 inch drill was a guess, guided by his experiments.

Rather than trying to bore out the barrels what about fluting them.

I love those Martini's they are superbly accurate

if weight is the issue why not simply reduce the O.D of the barrel in a lathe ? Theres lots of meat there so you could likely reduce the diameter by 1/3 easily.

I suspect he is thinking his way would not effect the fit and inletting seems like a waste of time to me, but some mothers children get off to such things..Colt had a different approach the stuck a stock on the single action and gave it a 7.5" barrel, again other than being collectable and high dollar it was a worthless endecor IMO, but to each his own and whatever blows one skirt up is acceptable.