My brass forming experience is very limited other than converting a few pieces of 30-06 in to * X 57 to try it.
I have some 8 X 57 brass that was converted from 30-06 (mixed head stamp civilian brass). I load 8 X 57 for shooting reduced cast rounds out of my 1905 Danzig GEW98 Mauser.
I am being gifted two nice Type 99 Arisaka rifles by a cousin - his Dad brought them back at the end of the war - I have seen and examined them numerous times over the years - unaltered and hung over the fireplace - earlier rifles with great bores, very minimal wear, etc.
I will get the rifles later this summer when we get together so I am accumulating what I need to reload - have a set of Lee dies coming, a NOE 314-262 FN PB mold, etc.
I have done a search on here as far as converting 30-06 brass to 7.7 and found several good threads. My intent was to pick up some 30-06 brass and converts trim, etc. - but - in one of the threads, several fellows mentioned that 8 X 57 (8mm Mauser) brass was a very easy conversion and that the only thing was that it would end up about 1mm short - i.e. - neck 1mm short.
In looking at the case dimensions of the 8 X 57 and the 7.7 brass in my Lyman Cast Bullet Handbook - 3rd edition - it looks like it would be a minimal "resize" in resizing the neck and bumping the shoulder down.
My plans are to only shoot cast and to use Red Dot as I do in my 8 X 57 Mauser in reduced loads for plinking and shooting the Arisaka rifles - not pushing them hard or hunting with them - strictly cans, paper and gongs at various yardages.
It doesn't seem like the somewhat shorter neck on the 7,7 converted from 8 X 57 should be an issue or a problem for what I am doing. However . . . I'm looking for anything from those more experienced than I am in regards to if there is anything I am not seeing or should be aware of if I use the 8 X 57 brass to do the conversion to 7.7?
Should I be annealing the neck and shoulder of the 8 X 57 before resizing to 7,.7 in a Lee FL sizing die?
Or . . if I don't have any issue resizing the brass as it is now, should I be annealing the neck and shoulder AFTER I convert?
In looking at the dimensions of the 7.7 case, it appears that the neck length above the shoulder is around .300. In looking t the drawing of the lead bullet that the mold I purchased there will be right around .300 seated down into the neck (the mold was designed for 303 Brit, 7.62 and 7.7). If the 7.7 cartridge case converted from 8 X 57 has a neck about 1mm shorter than normal, I figure the boolit can just be seated a tad deeper than normal and still not be protruding into the shoulder area very far and with reduced loads of Red Dot (starting load data in the Lyman CBH shows a beginning load of 10.00 grains and I will probably be using somewhere between 8.00 to 10.00 grains). With a light crimp, it should work just fine.
Any hints, tips, etc. on converting the 8 X 57 into 7,7 Japanese or things to look out for would be greatly appreciated.
AS far as to "why" I want to use the 8 X 57 - I have it and enough that I can convert around 100 casings and still have a good supply of the 8 X 57 for the Mauser. Ifr there is a reason not to use the
8 X 57 brass - then I'll have to start looking for some 30-06 brass to convert and a trim die for the 7.7 Japanese - with the current supply issues - the 7,7 trim dies are either out of stock or when I have seen them, they are priced at about three times what they normally sell for.
Thanks for any info / help - greatly appreciated!