7.7 Japanese .

Discussions covering the components and techniques of reloading for your long gun.

7.7 Japanese .

Postby RBHarter » 09 Oct 2021 16:02

Ok it's more like a 7.92×58 Arisaka .
I have like 12 pieces of real Norma brass for this so I'll be saving that for final tuning of "good loads" .......or some other "what I really mean is it's so expensive I don't want to waste it trying stuff to see it there's any point in having the good stuff" .

Moving on I hope that a blind man in welding gloves can tell the difference between formed 7.7×58 and the 270 Win FC headstamp , if not that's going suck almost as bad as a 300 BO in a 223 .

With that out of the way , I received the pre-owned .316 straight reamer and the CH 8×57 neck die . My immediate use of the reamer is completely wrong in both tooling and application but the cases run true and are now the same ID from the mouth to the shoulder/neck junction . At least until I load and fire them again .

My process was pretty simple and probably what a wildcatter would do to arrive at suitable brass in an unknown chamber . I ran the 270 case in a 270 WSM neck die then in the 7.7 die sans expander . It was decapped in the WSM die .
I used an experimental lube to good result and formed the case to a hard close and set the 7.7 die about 1/16 lower . Solid shoulder jam , loaded whatever I dropped last in Unique topped with Grits and a wax lube plug and fired in a 8' by 2" dirt bank plugged pipe out back and trimmed them back .001 behind the chamber mouth line . I should have annealed after the form and before the COW loading but I did it after that and after the ream .

5 test loads of the NOE 311-230 patched up to .319 from .312 suggested that for a reduced load I need more than 9.5 gr of Unique or that bullet just isn't in the game at this time . I dug out my 325-175 Lee and poured a few , about 50 of each as it has one side dechecked and one side checked . The throat is .320 and the nose should fit based of the paper patched above . I dechecked this one about 15 yr ago for a 32 Rem and the Lee push through left the .323 for the .321 Rem groove . I'll need to source a sizer for these but I think I'm going to go ahead and try the PB at .323 . It's a pretty soft alloy or was during the sort and cull .

The NOE cast at 234 gr while the Lee cast at 170.5 and 174.8 average of 10 from the core with O/U by more than .6 culled or relotted . I usually don't weigh lot "just shootin' " bullets but I had the scale out for the new to me RCBS 270-150 and 45-500 FN gc . Interesting results there ......the 270-150 2cav dropped 50 bullets +.8 to -.5 at 150.4 gr 38 laying in the 150.3-.6 . The 45-500 single however dropped from 528.5 to 531.0 for 27 after discarding 8 for obvious lines , fill out and poor closure . The 5 lights will be dummy and sizing tests . The remaining 20 in the lot are 530.4-530.6 , I tossed the heavy back with the culls .

So far I've reenforced the "when the shoulder becomes a neck" donut ream theory , satisfied my theory that close caliber steps can be used for neck dies , and not tried to use even start data for a 500 gr Marlin compatible bullet that weighs 535 + ready to load .
(Included I guess for my validation of alloy reference as much as anything)

it will probably be a while before I get to shoot any of the 7.7 stuff and I found several "practical" bullets I may passively look for before I add an Accurate undersized 321-180ish FP to the stable .
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