How do I get a .430 bullet to stay in a case with a .480 outer neck diameter?

[Invictaman]

I've gotten several obscure calibers going again but this one is a new level. I've got an old combo/drilling made by a German wildcatter around the turn of 1900. After doing a casting of the chamber, the case is basically a 43 Mauser trimmed down to total case length of 2.00". I started a post around 2 weeks ago and got some great help on possible cartridge identity and how a couple other people encountered the same obscure caliber and managed to recreate and reload it. Problem is, mine seems to be even odder than theirs as I have run into a major conundrum that they didn't. According to the casting, the wildcatter apparently trimmed down a 43 mauser to 2.00 inches, but then expanded the outer neck diameter to .480". I have no idea what his goal was in doing that, but basically, the perfect diameter for a 45 caliber boolit. So I expected to find that the barrel was 45 caliber. The hurdle is that the barrel slugs to .430" and has a .440" groove diameter. So, ok, I could probably use a .430 cast boolit in that barrel and be fine. But how do I get a .430" boolit to sit in a case with a .480" outer neck diameter?

[725]

What's the inside measurement of the brass at the mouth? Hopefully you have some thick brass.

[garandsrus]

If the groove is .440, you would want a bullet slightly larger than that. If the brass is .015 thick at the neck, you have a total of .472-.473, which might be close enough to .480 to work. You will need to size the case mouth to .470 or so to hold the bullet, regardless of what the chamber is.

There is a chance that the neck is even thicker that .015 if the case was shortened from something else. If it is .020 then you are all set with a .442/3 bullet.

[toot]

super glue? I have used it on 8/mm, heads that were loose, fired, not a problem. jmho.

[GhostHawk]

I agree with garandrus, you want bullet size 1 to 3 thousands bigger than the biggest dimension.

So in your case you would be looking at .442 to 443. That is too much too big for a standard .44mag cast boolit.

If you had a .442 size die you could try bumping them fatter then run them through the size die.
I discovered this by accident making some flat point boolits for a .30-30. Pushed 185 gr round nose that started at .312 up to .323, then sized them down to .314 for my Mosin that needed a fatter boolit.

[17nut]

Since this is a single loader, why not order a proper fitting stop ring bullet from Tom at Accurate?

[Mk42gunner]

I'd check the twist to have some idea of how heavy a boolit I wanted to try first. Slow twist, light projectile, faster twist, heavy boolit.

For a .440" groove diameter, the easy button is a mold meant for the .43 Spanish. They usually run .439-440". Or you could try to find a mold for the 11mm Mauser, which I believe is supposed to be .446".

Or where you thinking of paper patching?

Is this a BP or a smokeless round?

Robert

[ulav8r]

I don't know if it would work but paper patching might work. Post this question in the paper patching section.

[ndnchf]

I use .446" diameter cast bullets in my .44-77. With your .440" groove size, they could be sized down a little to work. BACO sell them.

[gloob]

You don't always have to size the bullet to fit the bore/grooves.

Check the chamber and leade. If the chamber fits a 480 OD case mouth, the leade is probably bored out to take 452-454 sized bullet, too. You don't need to do a casting. All you gotta do is seat one and see if it fits.

The massive size difference to the bore/groove doesn't matter, so long as you're shooting conventional cast or even jacketed bullets. It'll squeeze down to the bore diameter and accuracy will be fine. Work up your loads in the normal (safe) manner, which is a given for a wildcat. Just don't try to shoot Barnes solid copper bullets at a max load.

If you tried to shoot 430 cast bullets, and just let the case mouth float in the chamber, you'd get terrible leading from the gas blowby in the throat.

[Rockindaddy]

I have a Lyman .446110 boolit mould that throws a 340 gr .446 dia projectile. I could send you a bunch and you could size and lube them to .442. That's .002 over groove dia. The rifle should shoot like it has eyes! Find a neck sizer that will allow you to seat this 11 mm Reichspatrone boolit! Good chance your .430 projos if you use them; will keyhole through your target. Cast boolits should be groove diamenter or .002 over to perform well.

[ascast]

I suggest a proper chamber casting/slugging followed by a search for am 11mm Mauser chamber reamer. From what you have described sounds like they guy died of heart attack before he finished. Is this weapon smokeless proofed? There may have been a chamber insert that was intended to be used. I have a 577/450 MH that is chambered like that a bit; way oversized neck. IIRC the first version used a 468 bullet. Also, early cases were a copper foil and the bullet could get knocked out of alignment. So, a "roomy" throat is beneficial. Perhaps he was muzzle loading the bullet into a charged cartridge in the chamber. Whats the twist rate? I would fix the chamber, maybe make my own inserts.

[gloob]

Cast boolits should be groove diamenter or .002 over to perform well.

Not exactly. Cast boolits should seal the bore completely and quickly to perform well. And in the majority of guns, a bullet 1-2 thous over groove diameter is simply the largest one you can start out with, because that's all that will fit before you're completely filling the leade to within half a thous of clearance and/or starting to get tight at the chamber mouth. But if and when you can go bigger than that, there's little reason to use a tiny undersize bullet that is only 2 thous over groove but doesn't come close to filling the throat/leade and will let a lot of gas to blow around the bullet, melting and ejecting all your bullet lube out the muzzle before the bullet even gets to the bore.

Never ending song, this 2 over groove advice. OldTimer got so tired of correcting it, they made it a sticky on the forum.

So yes, it's theoretically possible that the previous owner died halfway through finishing the rifle, and that the chamber is cut to take a 480 case mouth, but the leade is only 442. But seeing as the OP left out the leade dimensions, it's way more likely that the previous owner knew what OldTimer does. The bore size can be way smaller than the bullet and it doesn't matter. So he left the original bore alone, despite reaming out the chamber and leade for 452+ sized bullets, which he probably shot hundreds of without any issue.

If your cast bullet is completely filling the leade and/or starting to get too tight to chamber at the mouth of the brass, and the bullet is still smaller than the grooves, then you have a problem that has to be fixed with machining. If your cast bullet fills the grooves but not the leade, you have a problem, but as long as you can easily just put a larger bullet in there that actually fills the leade within a thous, no need to do anything else. Even if that means the bullet is 12 thous larger than groove. The pressure curve will be changed, but you can still easily work up a load if you use the right powder for it. The force to swage the bullet smaller is relatively small, compared to the force needed to accelerate the bullet out the way, from zero to 3000 fps in a very short time. Peak pressure is not a major problem.

[fred2892]

What gloob says^^^^^. This is what you need to take note of. Make a chamber cast and measure your leade. Use a bullet sized to fill the leade. (The 577/450 martini has almost 8” of tapered leade to squeeze that .468” bullet down to groove size)


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[gloob]

Thanks. In revolvers, it might be different. Some have found that they get best accuracy with 1 thous over groove, even if their cylinder throats are larger. I suspect this has to do with the cylinder gap and less than perfect alignment of the cylinder throats with the forcing cone/bore.

[leadman]

Terry Weiland, a gun writer had a similar gun with a shortened 43 Mauser case that he wrote about. Think it was in a Rifle magazine. I'll try to find the article.
I have an original single shot 43 Mauser that I load for. I tried the .446" Lyman bullet but it did not work well at all. My bore is about .452" IIRC, been a few years ago I slugged it. What I did find is my chamber throat won't take a bullet larger than .450". I resize the Lee .452" 300 gr flat nose to .450" and it shoots very good. I do install the gas check and use a small tuft of poly-fil on top of the 2400 powder.
I also found out by talking with Andy Lee that his dad used a converted to tube magazine 43 Mauser. This case has the shoulder pushed back some on it so the Lee dies full length size will push the shoulder back too far on my cases. Doesn't cause a problem since the case is rimmed but for what the cases cost I do not full length size. Hope some of this info will help you out.