My version of a Jacket Trim Die

[garandsrus]

Rat Man,

Thanks for the quick reply! Very cool...

John

[DLCTEX]

Great work! Thanks for sharing.

[Rat-Man]

My pleasure. It's a small repayment of the vast amount of information that I have received from this site.

Rat-Man

[Rat-Man]

Just wanted to warn anyone that is thinking about building a pinch trim die about a problem that developed with the .22 lr brass jackets.
I started making bullets with the shortened jackets and the tips are folding.


I know a lot of people don't worry about these but I am getting a lot of them.
It seems that even though the jackets are annealed the brass is brittle enough that the thin edge develops a crack that continues to grow as the point is being formed.

I built this trimmer to remove the bevel and get the mouth back to the approx .010 of the brass case.


After trimming the mouth these are the results.


I think that my next step will be to try a 45-60 degree angle to see if I can skip the trimming of the champher that is created with the 30 degree cone angle.
I think that a real jacket being a lot softer would not have this problem, but those are way too expensive to use for cheap shooting.

When I get around to trying a new cone angle I will post the results. If anyone else beats me to it, please post the results of what you were able to accomplish.

[sagacious]

Looks good. Re-annealing your trimmed jackets in batches is another labor-saving solution. I have found that a second annealing doesn't hurt the 22lr brass any, and tends to make the annealing more uniform per batch anyway.

Cone angle is something you can experiment with, but you can also make the trim punch with only a very short tapered shoulder-- like a Lyman M die for case mouth expanding. The tapered section need only be a few hundredths long to pinch-trim the brass. That will work the brass less, but you may find that regardless of punch angle, the real culprit is the cutting/pinching itself. That may cause enough work-hardening of the jacket-mouth by itself. Re-annealing will correct any potential problems either way.

Keep up the good work.

[Rat-Man]

I tried re-annealing a few the first thing, thinking like you that it was work hardened. It didn't seem to make a difference, but removing the taper fixed the problem on both the re-annealed and the trimmed cases with out re-annealing.

I don't know what the final outcome of the cone angle will be but at least I can make some 45 grain bullets without to much drama now, because trimming .185 in length with out the pinch trim was a real pain.

[DukeInFlorida]

Right, and from the further reading that I did it's important to not kiss steel to steel. Doing so will immediately peen over the sharp edge of the die (not the tapered cone punch, but the die that the cone mates with)

Peening over that edge due to steel to steel contact will require re-sharpening the face of the die, or else the brass only smooshes (good word!) rather than cuts.

From the Corbin link that Duke provided it looks like you sould have the die set where it doesent cut thru 100% but leaves a thin section of brass, that way youre not getting steel to steel contact.

[jdjframes]

Nice work, looks like a Corbin unit.

I got all charged up to buy a Corbin until it dawned on me than I could buy a bunch of 22 Shorts for $250!

Jim

[Cane_man]

great thread from rat-man, anyone else try to make on of these pinch trim dies? can a trim die be made to trim 9mm cases?

[DukeInFlorida]

No, it's better to get one of the sets of cut off saw (harbor Freight) inserts from chuckbuster to do that.
I bought a complete set from him for adjustable length cutting of 9mm's, .40's, 45's, 5.7X28's, and 223 rem's. They drop in and out, and are adjustable for where they get cut. Makes the job of cutting the 9mm's down so very fast and simple. I owe chuckbuster a thread with pictures for this one.

The wall thickness on the 9mm's would be too thick for the pinch type tool.

great thread from rat-man, anyone else try to make on of these pinch trim dies? can a trim die be made to trim 9mm cases?

[Cane_man]

^^^that is what i thought, 9mm wall thickness was too much for a pinch trim die

[IllinoisCoyoteHunter]

Maybe chuckbuster could post pics and prices. I am VERY interested in sets for 9mm and 40 brass for the HF chopsaw.

[257]

I was wondering if you could post a drawing( sectional) of the die showing the parts in relation to each other don't really need dims. thanks

[Rat-Man]

I didn't make a drawing I just made it up as I went.
I will try and post a picture with the parts exploded, to help visualize how it works internally, in the next day or two though.
I didn't think about doing that originally!

[Rat-Man]

Pictures as promised.

Parts:


Assembly Order: