Originally Posted by
Phil
Glad to see Norma finally coming up with a more usable case. I have some measurements from old Japanese and English T38 ammunition that may come in handy for whatever:
Kynoch 1916: head dia. .4495" rim dia. .480"
Early Japanese 139 grain load: head dia. .449" rim dia. .479"
Late Japanese 139 grain load: head dia. .448" rim dia. .470"
Older Norma head dia. .447" rim dia. .467"
RP 220 Swift head dia. .440" rim dia. .467"
I would not use 303 British brass to make T99 7.7 Japanese cases as most 303 British brass has a head diameter of .454"-.457" whereas the Japanese T99 7.7 case head measures .472". Fired cases measure .476" which is really a stretch for 30-06 brass but I've never had a failure with it. I don't full length size it either. Another thing to think about is there were three distinct Japanese 7.7mm cartridges. The rimless T99, a rimmed 7.7mm which was nothing more or less than the 303 British, and a machine gun cartridge (T92 as I recall) that was semi-rimmed.
The original Type 38 ammunition was loaded with a round nose bullet that weighed, as near as I can remember, somewhere between 156 and 160 grains. I have one Kynoch Type 38 cartridge in my collection that is loaded with this round nose bullet. I really don't want to pull the bullet to weigh it. When I was a kid I bought several hundred rounds of 6.5mm Japanese military ammunition from Ye Olde Hunter. This was the old original Hunter owned by Sam Cummings. Quite a lot of this ammunition was loaded with the round nose bullet but most of it was the later spitzer 139 grain stuff. I still have one box (minus the lid which was lost long ago) of the spitzer stuff, still loaded on strippers. Never bothered to save any of the boxes from the round nose stuff. It must have been really ratty. The Japanese brass was really bad. Most of it split at the neck when fired. Remember this was in the late 1950's.
In the Smith "Small Arms of the World" book,7th edition, on page 714, top left illustration, far right cartridge, is identified as Japanese T38 round. It is indeed that, but it is the early round nose version. In all the text in the book the round is only identified as a pointed bullet.
About all I can remember about loading for the T38's is that 3031 powder and the Norma 156 grain bullet worked like gangbusters. In one T38 long rifle with a Lyman 48 rear sight and post front, it would group around one MOA all day long. With that long barrel it was pretty much flashless also. That was one point made by American press during the war "the Japanese ammunition has no muzzle flash" blah, blah, blah. I suspect it had less to do with the powder used and more to do with the quantity of that powder and the length of the barrel.
Be safe out there,
Phil