Making 12.7x48mm (.510 Whisper) Brass without a Lathe

[Dogtown]

Since there's renewed interest in this subsonic cartridge and still very little info about it, I thought I'd share the steps I take to make the brass.

Take some used .338LM brass, which for me are the oddballs that I cull outside of a specific weight range. Using a pipecutter, I cut and trim it to 1.875" which sometimes takes a bit of trial and error.

Once that's done, there's still some taper built into the case that needs to be taken out.

To do that, CH4D's die set includes an expander that opens up the mouth a tiny bit and straightens the case.

Once expanded and straightened, the case will fit on a .50BMG neck turner to do the time consuming portion of cutting the neck and forming the tiny shoulder.

It usually takes 3-4 passes to get it to the right amount of cut depth and length.

Next it's time to run it through the FL sizing die and then test it in the rifle's chamber to make sure it's all kosher. Early on I found that I wasn't cutting the shoulder back far enough and it took the right amount of trial and error to get the depth right for proper headspace.

Finally it's loaded with a 647gr M33 ball bullet.

 

[Geno C.]

I've always been kinda interested in the 510 whisper. Gotta justify the 50 cal can somehow, right?

 

[Dogtown]

It doesn't take a full-on .50BMG can built like a tank either...

 

[BIPMaster]

It doesn't take a full-on .50BMG can built like a tank either...

That is a hell of a can.

 

[Dogtown]

It's actually quite simple, with screw-on 60 degree cone baffles, and basically more or less the same as my .30 cal can but with a much larger bore diameter and a shorter baffle stack. Not only is the sound reduced to a little over a .22LR, but it's sunny out you can actually spot the big bullet in flight. It's a spear chucker for sure!

 

[Geno C.]

Yep. That's pretty baddass right there!

 

[biffj]

Thats pretty much the way I'm doing it only I run the case through the sizer die after trimming and then the expander. That way I have the case neck pushed back as far as it will normally go and the expander straightens the inside so the mandrel in the neck turner will run true. I've been chucking up the neck turner in the lathe with a 4 jaw and have a case holder that I made to avoid peeling all the skin off my fingers. Normally I run the cases through for a coarse cut to start with then turn to the final OD, run it in the trimmer to insure it is the proper overall length one last time. After that I run once more in the neck turner til the case mouth hits the turner and sets the shoulder in the right place. I've found that when turning necks it seems the cases stretch a little so a final trim helps make the shoulder come out in the right place. Even with the lathe its a painful way to do them. I've not found a good way to hold the cases in the lathe that insures they are held consistently.....maybe if I had a 5C collet closer I could make up an emergency collet that would hold the cases right.....as it is its tough to keep them close enough to insure good headspace on the tiny shoulder. I don't think it would matter if you were only shooting subsonics but too much headspace and supers could pop a case.

Frank

 

[leadbullet]

wow, now that's some brass prep.
cheers.

 

[sharvest]

Thanks for posting the pics!!! I'm even more hooked now

 

[Kiwi Greg]

It doesn't take a full-on .50BMG can built like a tank either...

Scotts cans are nice

 

[icentropy]

I know this is a really old thread but could I get more info on that can? material? dimensions? are those baffles just threaded to each other? I hope to do a .510 whisper this winter.