Fire Forming 8x57 brass (example)

[aliceinchains]

This is an example i got from another board. When fire forming 8mm to 7.7 Jap it's necessary to form it in the rifle without a bullet. The 8mm dimension from head to shoulder is shorter than the 7.7 so there would be gross head space problems until formed.

I formed them in a 7.7 sizing die, prime, load with a small charge of powder (preferably about .7cc of pistol powder), fill to the shoulder with corn meal then pack cotton in the neck.
To fire them, put the cartridge onto the bolt head making sure the extractor is in the case extractor grove, close the bolt and fire.

Now you have 7.7 sized cases for sizing and reloading.

In my experience there is no problem with strength. These cases and those formed form 30-06 are as strong as any others.

I have been reloading 150gr Hornady (Brit/Jap) SP with 38gr to 44gr of IMR4895 with very good results. The 44gr load clocked in at 2400 FPS.

One advantage to using the Norma cases is it's head stamped 7.7 for easy identification.

T99 chambers are typically within spec, not oversized. The T38 is typically oversized like mine for which I reform .308 cases in a special die I made.

[DonWally]

I decided to use 8mm instead of 30-06 cases. It is no problem to fire-form, just as you stated. I used Cream of Wheat but it gives the same result.

The cases are a little short but chamber and fire just fine! I annealed the cases also before fire-forming. Milsurp are supposed to be a little hard, but annealing ought to take care of that problem, or so I am told.

I used an electro-pencil to line out the 8mm designation on the rim, so that I could tell the difference.

Graf & Sons is supposed to get the 7.7 Jap and 8x56 M95 cases by the end of May(?).

[aliceinchains]

Thanks for your input DonWally. I also called Graf & Sons, they said May 31.:(