new cartridge 30 Federal MAG

@FROGO207 what is the purpose of this round?

I don't know if a .327 reamer will "clean up" a .30 chamber but you don't have to neck it down, unless you just want to use .308" bullets. People have been converting these to .32-20 for years.

So, .30 Bain and Davis (vs 357/44 Bain and Davis)?

If past wildcat threads and any indication, someone will be along to tell you who has already done precisely what you propose. . . but that's no reason not to!

Interesting. Big .32 fan and I happen to have a 30 carbine Blackhawk so I find this intriguing. What is the gain to this over shooting normal 30 carbine?

CraigC said:

I don't know if a .327 reamer will "clean up" a .30 chamber but you don't have to neck it down, unless you just want to use .308" bullets.

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To follow up on CraigC's point, I don't think a .327 reamer will do anything in a .30 Carbine chamber. I just tried dropping a .327 cartridge in my .30 Carbine Blackhawk. It dropped in easily, appears to head space correctly, and the cylinder rotated without binding.

I do have a New Model .30 Blackhawk, but it appears to be a transitional model, with chambers cut to recess the case heads, as was done with the Old Models. There is a bit of a chamfer on the chamber mouth, and the case rim appears to be headspacing on this chamfer. It might be interesting to see if the .327 rim will headspace correctly on a current production cylinder.

I suppose one could try to size some .327 brass with a .30 die, and load with .308 bullets. As eluded to, the back end of the case would be poorly supported. The rear of a .30 Carbine cartridge is .356" diameter, where the full body of the .327 is only .337" diameter. It may bulge the case just slightly, but not to the point where I expect to see a catastrophic failure.

Here you can see .327 on the left and .30 on the right of the cylinder. I expect I could fire them, just as people often chamber and fire .32-20 in .30 Carbine revolvers.

Might need nothing more than a throat adjustment for .312" bullets.

CraigC said:

Might need nothing more than a throat adjustment for .312" bullets.

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For that matter, would the standard .30 caliber throats size the .312" bullets down to an appropriate diameter for the .308" barrel? I had not given it any thought, but I expect this is what happens when shooting .32-20 through a .30 Carbine Blackhawk.

FROGO207 said:

I have a 30 carbine Ruger Blackhawk. I am going to get a spare cylinder and ream it for a necked down 327 with a 30 caliber bullet and relieve for the rim.

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I just noticed this part. That could make a difference. Are you going to try to find another .30 Carbine cylinder to ream? (Do they come up for sale very often? I've never looked). I am not aware of any Blackhawk cylinder chambered for a smaller cartridge that you could use as a doner.

Your other option would be to have a new custom cylinder made. While not a cheap option, you could then do exactly what you are proposing, and have a wildcat based on .327 FM brass, with correctly cut (not oversized) chambers, and the mouth sized for a .308" bullet. I think that would be a pretty neat revolver. And you could still put your .30 Carbine cylinder back in to shoot those cartridges. Sounds like a neat project.

FROGO207 said:

The main reason was that after a couple cylinders full of lead bullets are shot I need to clean them with a brush so the rounds will go fully in the cylinder and not tie up the revolver. Looking for a way to avoid this and still use lead bullets. I would think that a 32 bullet would spit a lot of lead when entering the forcing cone.

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I have noticed that my .30 Carbine is very picky about brass length. Slightly too long brass or just dirty chambers, and it doesn't want to chamber fully. Brass just slightly short, and I get light firing pin strikes. That's part of the reason why I recently bought a revolver in .327FM. Headspacing on the case rim pretty well takes care of those issues.

GarrettJ said:

For that matter, would the standard .30 caliber throats size the .312" bullets down to an appropriate diameter for the .308" barrel? I had not given it any thought, but I expect this is what happens when shooting .32-20 through a .30 Carbine Blackhawk.

Click to expand...

I'd rather do that in the barrel.

I understand the goal here is probably to be able to shoot cheap .30 Carbine bullets, but with a stronger case that has a rim. If that's the case, try experimenting with using 100 and 110 grain .308 bullets in the .327. I may return to trying that, but using a .30 Carbine Lyman M die instead of the .32 M die. I figure the smaller expander should fix my neck tension issues I had.

Then to crimp the bullets, Lee's collect crimp die would do the job fine since it will make its own crimp groove in the bullet.

CraigC said:

I'd rather do that in the barrel.

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Using a slightly larger and longer forcing cone.
Another option for your cylinder is to take a 44 or 45 cylinder and make inserts to fit the chambers but to be chambered for the smaller cartridge. Or do it correctly and make your inserts just a couple thousandths too big (diameter) for the cylinder and shrink fit them. Put the inserts in liquid nitrogen and heat the cylinder.


Kevin

Might be a fun cartridge in a single six too...

FROGO207 said:

The plan is to make a purpose built cylinder and reloading dies to make use of 327 brass and a .308 barrel. Blowing out the brass would work but I would think brass life would be short. I suppose I could get a used 357 cylinder and sleeve it as that would be the correct size cylinder to use. Still in the planning stages

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Sounds like a good plan. Annealing the brass might help but you would need to anneal it down to the web so you could end up making it too soft. I agree with your thought of a new cylinder.

If you go the sleeve route, make sure your gunsmith understand shrink fitting the inserts. Loose inserts “might” work okay. Heat fitted and lined bored will be as good as it gets.

Good luck with the project and please, keep us posted.

Kevin