7 LRM brass forming????

[Raufoss]

My boss has decided to ask me to find how to make 7 lrm brass.
Mainly because we are in canada and we dont want to be depending On gunwerks for brass.

I tried to ask to gunwerks but got nothing from them expect fom : it take alot of dies..

So if anyone want to share is experience in making brass for this caliber i will be grateful.
We have the time and money to make those brass.
I know 7-375 exist and it is a shorter neck version but is not what my boss want.

Thanks

 

[Raufoss]

Really no one have experience?

 

[wadebrown]

You are going to have to push the shoulder back a little, not sure how much see the cartridge specs for LRM and 375 ruger. Thread some round stock to 7/8x14 and ream a pilot hole that is just slightly larger than the pilot on the reamer then run the reamer in all the way. After you have reamed the 7/8 x 14 you open the neck size quite a bit, because you are trying to push the shoulder back in stages. Repeat the process with a die made up the same way but not as oversized a neck, run the brass in. Finish it up with the actual 7 mm LRM fl resizing dies and your shoulder should be pushed back enough and ready for fireforming.

The method of pushing the shoulder back in stages makes it easier on the arms and linkages on the press, you could just pass the 375 Ruger brass through the 7mm LRM FL die in one pass. I would recommend you anneal the brass both before and after pushing the neck back and don't worry about concentricity until the fireforming is done.

Hopefully this helps,

 

[Bluejazz]

Why not just buy it from Gunwerks?

 

[wadebrown]

Why not just buy it from Gunwerks?

My boss has decided to ask me to find how to make 7 lrm brass.
Mainly because we are in canada and we dont want to be depending On gunwerks for brass.
Thanks

That may be the reason.

Another and probably better way to do is to have Mark Spencer make you a full-length sizer. Mark's sizer uses one piece shoulder and neck inserts and the price for custom dies is $137 USD this is with one shoulder insert, have him make up 3-4 more for gradually pushing the shoulder back and necking down the brass.

My earlier post had a mistake as I forget yuo were not just pushing the shoulder back but also significant reduction in the neck. The method use Mark's dies is probably a better way to go.