Gas check flair tool

[Brad]

Lookng at the modified M die set up Rick has for flailing checks made me think about making something similar.
I decided to make the entire thing forms scratch, good learning lesson if nothing else.
The body is made from 12L14, threaded to fit press with a 3/8-16 tapped hole in the bottom. The punch is made from annealed O1 as is the anvil the fits the shell holder slot.
The machining is a bit roug in spots but the nose of the expanding spud is polished well enough that checks come off easily.

Only issue I see is that it is a bit fiddly to get the check centered under the expander. I thought of cutting a small indent the check could sit in but then a new anvil would be required for each size.

What I think would be better is having the expander as part of the shell holder and have the flat anvil be part of the die. Sit a check on the expander, raise the ram to flair, and lower.

I see more time in the garage later today.

 

[Rick]

Here's another type of punch sizer. The shaft is the same on both ends. Size a check, rotate to the other end & size another check. The collar slides back & forth and easily removes the checks. This one is in 35 caliber for the 357 mag.

 

[Ian]

Nicely done, looks like you're getting the hang of it!

I like your second idea MUCH better, love to see how it works out. A tapered hole leading to the anvil in the top die would help correct any misalignment between punch and die (most presses are a little wiggly) and help the parts come together. Another thing that would be super-handy wold be a floating collar on the punch like the RCBS primer pocket swaging tool that would bottom on the press plate when the ram is fully lowered so it would pop the check off the punch nice and square.

Edit to add....I see Rick had the same idea while I was typing!

 

[Rick]

Only issue I see is that it is a bit fiddly to get the check centered under the expander. I thought of cutting a small indent the check could sit in but then a new anvil would be required for each size.

I thought of that the very first time I used that set up. The only reason there isn't such a slot in mine is that I would need to buy a new extended shell holder for each caliber and then either pay a machine shop to do it or impose on someone for favors.

 

[Brad]

The way I made this the threads that fit in the press and the punch in the body both have some slop. That is needed to make it easy to change out parts. This allows the punch to float a bit. By having the anvil be dead flat on top the punch can float to hit the anvil square.

 

[Rick]

Another thing to be aware of while making this type of punch Brad is the length of the anvil. Mine is too long resulting in the Rock Chucker ram only raising about half way while sizing the check. The Rock Chucker doesn't have nearly the amount of leverage/force at half stroke that it does with a full stroke. This is one of the reasons I mostly use the punches made from the center punches except for the 357, that one works really slick. A machinist friend made that for me, I think the center rod is drill steel and a standard size just happened to be perfect for 357.

 

[Brad]

My feeling exactly Rick. I looked at the distance from top of shell holder to bottom of threads in press and it isn't but 1/2 inch or so. I took that I to account when I made this, the ram is at 3/4 Starks or more when the flairing occurs.
When I make another that has the punch as part of the shell holder that part will be but 1/2 to 3/4 inch long. It will required a different punch for each size but a single flat anvil that threads into the press will handle all sizes just fine. Much easier to machine too.

 

[Ian]

+1 Rick, I have several tools that can't be adjusted to do the work at full ram stroke and it can be a royal pain. It's also nice to be able to set the tool up so that the operator just cycles the press handle stop to stop.

 

[Brad]

Another advantage of the anvil being threaded into the toolhead is that it can be bored out to allow full stroke of the ram. Think of a die body bored out to a depth of 1/2 inch then flat side with no thru hole. This can be threaded in and out of the press to give full stroke and good flairing. Just make the shell holder portion short enough to make this easy to achieve. Not a big deal.

 

[Warren4570]

Question
Why flair out the gas check? For easier placing when installing them?

 

[Brad]

Yes. Some bullets have a shank just a bit too large and the checks tend to shave metal on seating. This flair eliminates that shaving of metal.
We can't control, within reason, shank size so we alter the check to eliminate the problem.

 

[Warren4570]

Thanks Brad good to know and makes complete sense now.
I notice some fit tighter than others. I would imagine it helps them seat more squarely on the bullet's base as well.