A Shared Mold for .303 Brit and 7.7 JAP?

[Hanzy4200]

I am planning to load both of these calibers in the near future. I noticed both call for a .311-.312 diameter pill and around a 180 gr weight. Is there a mold that would be optimal to get the best of both worlds? I am open to any ideas, but I prefer to buy from Accurate Molds. Tom has treated me well and I plan to send as much business his way as possible.

[Kraschenbirn]

I'm certain you've read/heard this before but, first off, you need to slug your barrels to determine their actual groove diameters then, you can start shopping for a mold design that drops a boolit that can be sized to the larger of the two. From there, you can size your boolits down a little more for the other (smaller) bore. After after a bit of 'beagling', I'm able to load the Lee 312-185 for three calibers...7.62x54 Russian, 303 Brit, and 7.65 Argentine; sizing to .315 for the Moisin and .313 for the other two.

Bill

[Outpost75]

Recommend that you cast chambers in both rifles. You want a bullet that drops to chamber throat diameter, not barrel groove diameter. Most .303s, 7.7 Japs and 7.62x54R Russians require cast bullets of .314-.315" diameter if you want them to shoot accurately. The .311-.312 diameter you cite is common for arsenal jacketed bullets in these calibers, but that is a different breed of cat. Accurate 31-215B is a good choice for these.

[Hanzy4200]

Recommend that you cast chambers in both rifles. You want a bullet that drops to chamber throat diameter, not barrel groove diameter. Most .303s, 7.7 Japs and 7.62x54R Russians require cast bullets of .314-.315" diameter if you want them to shoot accurately. The .311-.312 diameter you cite is common for arsenal jacketed bullets in these calibers, but that is a different breed of cat. Accurate 31-215B is a good choice for these.

Good advice, thank you. I don't know why I quoted jacketed dimensions, I know better.

[tomme boy]

The 215b works awesome in 54R and 303 brit. My buddy has a very nice P14 and we are getting hits out to 400yds easy. A lot is going to depend on your throat diameter and bore diameter. But Al can make it whatever you want.

[JM7.7x58]

One of my Arisakas has a groove diameter of .3165”.

By the time my 7th series Nagoya was made in 1943 the oversized bore was considered to be an acceptable tolerance.
JM