Pinch Die

[deltaenterprizes]

Forming the ogive on some 6mm bullets I am making from 22 mag brass gave me fits!
One of the problems was that the length of the cases were different sizes I used a HF mini saw to cut them but they must moved in t jig.
I printed a picture of Corbin’s pinch die and made a print frame m it and will soon be in the shop making chips!

[clodhopper]

Nice, looking forward to reading about the details.

[rbt5050]

i had the same problem years ago when i was making bullets. the pinch die is the way to go.

[bigjake]

how does the pinch die work?

[plus1hdcp]

Looking forward to hearing/seeing your progress with the pinch die. Best wishes.

[nun2kute]

i'd like to know more. is length of the jacket the only issue your having ? what are you trying to make. what's causing you fits ?

[deltaenterprizes]

i'd like to know more. is length of the jacket the only issue your having ? what are you trying to make. what's causing you fits ?

Making 6mm/243 Bullets from 22 mag brass, the varying lengths cause a problem when forming the ogive.

[clodhopper]

A pinch die trims jackets, when used right makes them uninform length.

The die pinches the brass between upper and lower parts. Set to tight wrecks the pinch edge, set to loose, does not pinch the jacket off.

[nun2kute]

hollow point, open tip, spire point ?
getting wrinkles ? I've not tried the mag brass, but the LR brass is real easy to wrinkle if it doesn't have lead behind it to help mash it over the ogive. the lead kinda supports the brass from wrinkling.
keep us posted on your progress

[Scrounge]

Forming the ogive on some 6mm bullets I am making from 22 mag brass gave me fits!
One of the problems was that the length of the cases were different sizes I used a HF mini saw to cut them but they must moved in t jig.
I printed a picture of Corbin’s pinch die and made a print frame m it and will soon be in the shop making chips!

Some photos would be helpful, or a link to photos elsewhere. I'm quite interested!

Bill

[deltaenterprizes]

Google Corbin pinch die and it will come up, that is how I found it.
I am not very skilled with all this new fangled electronic wizardry!
I just read email and surf the web!

[MUSTANG]

how does the pinch die work?


Hopefully this picture will show you and the several other People with the same question on how it works:

265987

See the exposed portion of the case/jacket being split? The cone of the punch then "Pinches" the case in a total circle where the cone of the punch meets the rim of the die (case/jacket inside the die); cutting the excess length of the jacket off.

[garandsrus]

I am pretty sure in that picture that the punch is being withdrawn. The jacket is already split/creased at the desired length. Wiggling the split Portion of the case will cause it to break free from the case.

Here’s a set of pictures and instructions on using the dies. http://www.corbins.com/et-2-s.htm

I made a pinch trim die for 7mm jackets and it works very well. You will need to heat treat the base punch at the least, since it has the sharp edge. I heat treated both punches. I used a steeper angle on the punch and my brass splits into about 6 petals. Most stay attached to the case until they are wiggled and then break free. If you were doing a lot of brass, I would think that you could tumble the cases to break the petals also.

[deltaenterprizes]

I am pretty sure in that picture that the punch is being withdrawn. The jacket is already split/creased at the desired length. Wiggling the split Portion of the case will cause it to break free from the case.

Here’s a set of pictures and instructions on using the dies. http://www.corbins.com/et-2-s.htm

I made a pinch trim die for 7mm jackets and it works very well. You will need to heat treat the base punch at the least, since it has the sharp edge. I heat treated both punches. I used a steeper angle on the punch and my brass splits into about 6 petals. Most stay attached to the case until they are wiggled and then break free. If you were doing a lot of brass, I would think that you could tumble the cases to break the petals also.

I made a copy of ET-2, I can’t get a good look of the end of the cone shaped part to finish the end.
Can you post a picture of yours or send me a pic?

[deltaenterprizes]

I talked with a mechanical engineer friends of mine and he suggested that the best top punch angle on the end would be 45 degrees.

[garandsrus]

My punch has about a 30 degree taper down to the inside diameter of the jacket. The straight part at the tip is about 1/4” long and serves to make sure the jacket is pushed all the way into the die before the case is expanded and pinched. The outer diameter of the punch doesn’t matter much, it is probably about 1/2”. I will try to post a couple pictures.

[garandsrus]

Here are some pictures:

Trim punch
266066

Case ready to enter die body. It is pushed in by the trim punch
266067

Case fully seated in die body, trim punch backed out to show length getting trimmed off
266068

Bottom of trim stroke
266069

Ejected
266070

Ejected and petals snapped off
266071

[plus1hdcp]

Great pictures Garandsrus and thanks for sharing.

[deltaenterprizes]

Thanks you sir!

[deltaenterprizes]

We had some cool and dry weather so I was able to harden the pinch die parts today!
It works like a charm!
Before I hardened the parts the cutting edge would roll and the die would not cut now it works!

[garandsrus]

Congratulations! Do your petals look similar to my picture before snapping them off? Did you go with a 45 degree angle on the punch?

[deltaenterprizes]

Congratulations! Do your petals look similar to my picture before snapping them off? Did you go with a 45 degree angle on the punch?
I went with the 60* like yours.
I get one split, but I have not adjusted the length and it is taking about a quarter inch off.

[bigjake]

Are the cases bell mouthed or ragged? Do the dies cut 22 lr cases? how about thick walled cases?

[garandsrus]

The pictures I posted were of 7mm jackets. You can see the trimmed mouth in one of the pics.

[plus1hdcp]

I need to learn more about hardening the steel. I believe a MAP torch would be able to get it hot enough but to be honest, I haven't made anything that has needed hardening. Some might have benefited from it but using your dies and punch as a cutting device is another thing.

[bigjake]

The pictures I posted were of 7mm jackets. You can see the trimmed mouth in one of the pics.

From the looks of the trimmed case, it will need a second trimming in a reg case trimmer. correct?

[garandsrus]

It looks a lot better at the actual size. The length is very consistent and they close up nicely.

[deltaenterprizes]

Are the cases bell mouthed or ragged? Do the dies cut 22 lr cases? how about thick walled cases?
The case mouth is slightly belled because the cavity is a little over sized, it looks similar to the mouth of factory jackets. This was for 22 mag brass. I have not tried 22LR because I use them at full length.
I think I would make another one for 22LR with a smaller cavity.
I will have to try it and see how it works!

[garandsrus]

The jacket will be completely inside the core seating die so any belling that is created from the trim die will be removed there.