Expanding a holow base with smokeless

[Cowboy_Dan]

I recently recieved a NOE .454-276 Keith mould in the RG2 hollow base configuration. I plan to fire these in my Mil Thunder Five chambered in .45 Colt/.410 3". The cylinder has no throats (.480" the whole way down, a .45 Colt cartridge will fit into both ends of tye charging holes) and the barrel has a groove diameter of .457" so that it can be converted to .45-70 with a simple cylinder swap (for sales in CA and MD). I've tried firing boolits sized .458" in it, and it worked to some extent, but I don't feel comfirtable using such large boolits in it.

So, here's my plan. I have cast some of these NOE hollow base boolits out of 30:1. I plan to size them .454" and load them over a stout charge of a fast powder in hopes that they will swell up and fill at least as much cylinder as one sized .458" and then continue on to fill the barrel. Am I way off base here? Any other cons8derations (heavy crimp, etc.)?

[mdi]

Shooting .458" bullets through a .457" groove diameter barrel is OK (I routinely shoot lead bullets up to .003" over groove diameter. I think if you fired a .454" HB bullet in a .480" cylinder there may be problems. The bullet will fill the cylinder an exit at .480", and the bullet will be .023" larger than the barrel. I'm no expert, but that is excessive and I wouldn't do it...

[Cowboy_Dan]

Mdi, I appreciate your concern, but I am under the impression that only the hollow portion and maybe just a little ahead of it will do any much expansion. And even then, I doubt it will make it all the way to .480", I'm hoping it will get up to .460" or so. As to your other comment, I also regularly shoot boolits of .002-3" over groove diameter in my other guns. The reason I am uncomfortable doing it in this one is that a .458" boolit makes the case visibly swell in the neck area which can't be good for brass life and probably causes excessive neck tension. Furthermore, the neck diameter of loaded rounds comes to .4797", which only leaves .00015" per side for boolit release, which is about 1/10 of what I've seen recomended as a minimum. Of course, I've been wrong many times before and may be here as well.

[mdi]

If so, what is going to happen to the .023" larger diameter, even if it's the skirt, when fired? Personally I think the base will be pushed forward and open when fired and the body of the bullet enlarged. What will contain the the bullet from expanding as much as it's allowed by the cylinder? I see, at least, a lot of "lead spitting" from the gap, and possible damage at the forcing cone. But I don' know much, try it.....

[beagle]

Some thoughts here. First off, it doesn't take a lot of pressure to expand a hollow base. In fact, hand cast 358395 Lyman wadcutters expand nicely at wadcutter velocities and pressures. Next, the bullet is looking at a LOT of freebore and you'll probably get some blowby and a nice amount of leading plus the pressure will be lessened by the freebore as that's how Winchester and Ruger tone down the pressure in .458 Win Mags. The magic question is what will happen the .480" bullet hits the .458" barrel. I'm speculating that the forcing cone will iron it out and it will shoot normally but you're on your own on this as it's your gun. I've shot loads of .462" sized bullets in a Number 1 .458 Win Mag with a long throat and no adverse pressure signs but the Number 1 is strong and has a throat that looks like the on ramp on a freeway.

Was offered a Colt .44 Magnum once way back in the days before the Anaconda. Looked it over and it was a M1917 Colt with the bored through chambers. The guy had it loaded with .44 Magnum ammo with the tips cut off for cylinder clearance. Swore that it shot good. Naturally, I passed on that combination but the freebored chambers and the .452" barrel apparently let him get away with this practice./beagle

Be careful what you do./beagle

[leadman]

Hadley is a guy in Texas that casts and makes or converts cases for many obsolete cartridges and loads them also. He stated that Unique is what he uses in cartridges in loading which the correct size boolit that fits the bore will not fit in the chamber. He claims Unique will expand softer alloy boolits to fit the bore much like black powder does.
I have a 43 caliber Mauser 71 in which the bore is .457" but the largest boolit the chamber throat will take is .450". I use 2400 with poly-fil and it shoots fine with no leading. I am also able to shoot the Lyman .446" boolits the same way with no leading. My alloy is soft at around 12BHN.
Try it and post what the results are.

[Cowboy_Dan]

As we speak, I have 10 cast in 30:1 loaded over 5 gr of Red Dot with a mild crimp waiting for a chance to get to the range. I will attempt to trap them for inspection. I'll report back as to my results, I expect that the forcing cone will treat these like a choke does a Foster slug.

[Mk42gunner]

This might be a case where a cylinder length piece of brass would be good. I have read of people using 9.3x74R brass in 3" .410 chambered T/C Contender barrels, it might work well in your long cylinder.

I don't think you will find any accuracy with the large chamber diameter and the big step down to bore size. To me it sounds an awful lot like the .41 Long Colt with the size discrepancies.

I could be wrong and your Judge will shoot like a K-38, but I don't think so.

Good Luck and keep us posted,

Robert

[Cowboy_Dan]

So I shot the 10 I had loaded yesterday. Did not notice any lead spitting out the culinder gap, but not sure what I would be looking for for that. Accuracy, while passable was nothing to write home about, but the charge has room to be upped a bit to try for that. Holes in the target were nice and round as expected from a Kieth design. Cases ejected as well as with other loads and no pressure signs on the primers. This morning I emptied out the boolit trap and found 2 which had not been buggered too badly to measure. Front band is still .454 like it was sized. Remaining bands (both over the hollow base to some extent) measured .461-.463 (groove is .458). I think this suggests that there was still sufficient gas pressure to expand the base as it exited the barrel. All in all, I think it was a safe and successful test.

[GWM]

That's interesting...