View Full Version : 32-40...use 8mm barrel for better bullet selection ???

Magnum Wheel Man
August 28, 2008, 10:42 AM
so on my custom Remington roller bench gun project... I'm still trying to finalize the cartridge...

I want a lower pressure black powder conversion cartridge, & have been considering the 32-40, & 38-55 / 56 at the top of my list...

unfortunately, all the 32 caliber bullets for rifles ( & bullet molds ) that I've found ( except for one pope style that is still flat nosed but listed as a semi spitzer ), are designed for the lever action rifles, & are all flat nosed...

I'm trying to build a bench rifle out of this "roller" that I could shoot at 100, 200, & 300 yards... & IMO, the flat nosed bullets are less than ideal for 200-300 yard target work...

the 8mm barrels are only a few .001's bigger than the BPC 32 barrels, so any stock 32-40 cartridge could safely shoot down a properly chambered 8mm barrel( albeit probaly less accurately )... the twist rate of the 8mm barrel is likely more conductive to longer range bullets, weather talking cast gas check lead, or copper jacketed...

so... ( not that I would ever compete )... but would there be any competition issues, with a 32-40 chamber on an 8mm barrel, if the barrel is marked as chambered in 32-40???

any reloading issues that anyone could see ??? this being a single shot rifle, the OAL shouldn't be an issue, & I'd think the 8mm bullets would work with the 32-40 dies ( maybe an issue with round nose or spitzer bullet with a flat nosed seater ??? )... but if the bullet wouldn't start, an 8mm expander could be added to the 32-40 loading process...

appreciate any suggestions I might get...

August 28, 2008, 11:52 PM
The 32-40 Winchester case tapers from 0.424 to 0.3455 and then has a neck of 0.3388 (OD) with no appreciable shoulder. The ID of the neck is slightly under 0.321. That gives you a wall thickness of about 9thou.

If you were to open the neck by 0.002 to 0.003, I would say you woild have no problem at all with the 8MM bullets loading in the dies. Brass thinning would be negligible, in my opinion. You will have to have the seat/crimp dies relieved for the fatter neck, even if you use an 8MM expansion plug in the sizer. I would also relieve the neck portion of the sizing die, to reduce the metal working of the cases.

I don't know about the rules for competition in any of the replica/antique groups, but those questions should be easily answered by the organization. Just ask about using an 8MM barrel on a 32-40, as if you were rebuilding.

Lee will build dies to spec for a fairly reasonable cost. You might try talking to them and seeing what they recommend. All you are asking for is a mold for the 32-40, with a (more) spitzer nose.

Those are my thoughts and probably worth about what you paid for them :D


Jim Watson
August 29, 2008, 07:13 AM
Flatpointed or roundnose cast bullets were standard if not universal for scheutzen and benchrest at 200 - 300 yards. Paul Jones makes spitzer style .32 moulds, although the effort kind of fizzled in larger calibers. The pointy bullets are cataloged but seldom used.

There is no technical reason an 8mm-40 would not work; there were even period target rifles made or rebored to .33-40 for .338" bullets. The purpose was to get a heavier bullet at a reasonable length. Sectional density is not unlimited for cast bullets.

There is an economic reason. A GOOD .324" or so mould would have to be obtained, dies would have to be made or modified, and you might even have to have a chamber reamer custom ground. A common complaint of .38-55s is that chamber necks are too tight for a bullet made to fill the grooves. I don't know if the .32-40 shares that problem, but you should find out before you buy stuff.

Magnum Wheel Man
August 29, 2008, 07:23 AM
thank for the comments guys...

but you should find out before you buy stuff.

I'm just bouncing out eye deers, & doing research... it'll be almost Christmas before I get the rifle out of hock, ( unforutately I wasn't "planning" on buying it, & it's in my "layaway line" at the shop )...before I can even begin working on it... but hope to know what I want to do to it before then, & have some stuff here waiting for the rifle to come home...

... I'm hoping the work can be completed, & the rifle, scoped, & finished over the winter, & get some test cartridges loaded, so I can wring it out 1st thing next spring, & get some "good" cartridges loaded early spring, for playing with next summer...

August 30, 2008, 08:24 AM
First thing you need to do is establish the exact groove diameter since guns chambered in .32-40 varied from 0.318"-0.321" which is why some original Remington, UMC and Peters ammunition was loaded with bullets having a diameter of only 0.317" The throat will also need to be measured since it was somewhat common for the throats to be undersize of the bore as in the throat being 0.318" and the groove diameter being 0.320" - granted 0.002" difference doesn't seem like much but it can make the world of difference between an accurate rifle and one that is not.

If your particular bore in on-spec with a 0.321" groove diameter and the throat is also 0.321" and your reloading dies are, if necessary, honed to match the gun's spec's, there is no reason why you cannot run 0.323" cast bullets. If you try running oversized jacketed bullets, you'll run the risk of blowing it up in your face because of the increased and erratic pressure.

It is not uncommon and in many cases it is advantagious to accuracy to run cast bullet that are 0.001"-0.003" larger than the groove diameter. Assuming you're going to be running this rifle on black powder, you'll be casting bullets from a rather soft alloy anyway so there is very little pressure issue with the slightly larger diameter bullets. If the reloading dies are not properly sized however, you will run the risk of damaging the bullet upon pushing it into a neck that's too tight. I have seen modern bore liners chambered in .32-40 with a 0.316" bore diameter and 0.323" groove diameter (same spec's as the 8x57JS)

I doubt you're going to gain much of anything, if anything, going to a pointed or semi-pointed bullet. Most .32-40's use a 1:14 twist and when combined with lower velocities, the capability to build bullet RPM's will limit the bullet length that can be stabilized. Quality FN & RN bullets are plenty accurate for 300yd shooting especially considering they've been used for over a century at ranges well beyond that in the larger bores. My advice is to go with the heaviest FN bullet you can get to shoot the best. Sometimes the more you over-engineer the problem, the larger the problem becomes and the less answers you'll find.