7.7 Japanese

AJC1 said:
Mine lived in Redondo California for about 60 years. Low humidity. Now it lives in my safe with 2 rechargeable dehumidifier blocks.
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I boiled my gun about 10 years ago to clean it. Got it for $175 on a trade. Love historical guns! Your gun is special
 
AJC1 said:
Mine lived in Redondo California for about 60 years. Low humidity. Now it lives in my safe with 2 rechargeable dehumidifier blocks.
Click to expand...
thanks for the post today! I was kind down because of the rain and no sunlight and Kiaboys tearing everything up here in Seattle. You know what I mean! you were here for a few years. Anyway, good post! maybe slow rifle shooting is my new jam!
 
I found some more of my notes. Even though I've had good success with the 4350 powders, actually the best 7.7 groups I've ever had were with Varget and 150g .312 Hornady. Even had one sub-.5 MOA group at 100m. :eek:
 
7.7Jap is based on the British .303 Mk.7 cartridge but cut into a rimless shell to help it feed better in a Mauser action. In theory I’m guessing this means any powder and projectile that works well in the rifle No.3 Mk1/1*. (?). My goto powder for the No.3 is IMR 4064 with IMR 4895 as a standby substitute. The Sierra 180gr RNSP is a great hunting bullet for the .303 so it should play well in the 7.7 also. The Remington 174gr FMJ component bullets are excellent for target shooting but I haven’t seen any in years. Maybe check out the auction sites.
 
I’m going with a min charge of BLC-(2) 38 grain with a lead bullets looking around 171.5 grain (odd weight) will add a bit of black powder lube to the groves



IMG_0521.jpeg IMG_0520.jpeg
 
I have shot my 7.7x58 Arisaka every weekend after Thanksgiving for the last 5 years or so. Reloader 15 and 19 grouped my Hornady 150 and 170gr bullets well at 100 yards but I ran out of powder during the Pandemic to fine tune my tests. I switched to IMR 4350. This powder has worked well but again, I ran out of powder. I buy at local stores and the closest one I found is a 4-1/2 hour drive away and a pound of powder is $75. I plan to drive 41 minutes south and swtich to AA4350. The last I checked, it was around $50. I've tried 4064 in the past by my accuracy load included a heafty load and recoil. Reloader Powders had less felt recoil and IMR4350 was not so bad. A new powder I acquired is 2400 and will use these as follow up shot practice using Lee 170gr cast PC bullets.

The cases I use are LC and Norma. The only split necks I have acquired is because I didn't anneal the neck. I use RCBS dies and a Lee Custom neck sizing collet die. I get near zero runout using this die compared to using my RCBS die to resize a neck. My RCBS dies crush the fireformed shoulders on my cases, which I don't like. My first resized cases are sized to SAMMI length. My newly resized cases are just under chamber length. I use a Sinclair chamber length tool to determine the chamber length, managed to seat a Hornady 150gr bullet can touch the rifle, and shot rounds with various lengths from the rifle. Seating depth makes a difference. I wish my 174gr bullets could touch the rifling when seated in my extended case. I'll begin my tests again using AA4350 which is reported to be a good powder for the T99.

I sandbag and bench my rifle and have a odd way of lining up my sights because I think it's better. After placing the fore end on a sandbag, I raise the butt with my fist. But to line up the sights, I look over the aperture and line up the front sight under the target and lower my head onto my stock comb to reduce torque, then raise the stock with fist. I add pressure to the trigger like a handgun. My targets are made to help center my sights and get the best sight picture. I use a big red meat ball cut out of a bright colored cardboard sheet from the $1 store. A triangle in the same angle as the front sight ends with the tip on the center of the meatball. Two similar triangles point downward like a radiation sign so I can center the front sight better. I want to reduce error.
 
GeoDudeFlorida said:
7.7Jap is based on the British .303 Mk.7 cartridge but cut into a rimless shell to help it feed better in a Mauser action. In theory I’m guessing this means any powder and projectile that works well in the rifle No.3 Mk1/1*. (?). My goto powder for the No.3 is IMR 4064 with IMR 4895 as a standby substitute. The Sierra 180gr RNSP is a great hunting bullet for the .303 so it should play well in the 7.7 also. The Remington 174gr FMJ component bullets are excellent for target shooting but I haven’t seen any in years. Maybe check out the auction sites.
Click to expand...
I've herd using starting 303 loads as a basis of load development, absent any real data on a powder listed for the 303 and not the jap. I have not done a direct comparison myself. What very little data I did get from my dad was the best he found was imr 4064 matching well with your comment. I have barely any imr 4895 so trying that is a dead end at 55+ dollars a pound.
 
Auctioned on an email chain from my dad and western powders. The load sent to him was 50.0 to 55.5 grains of hunter under a 150 grain bullet at 3.050. I chose 54.0 and built 50. Have very limited supply of this powder left and these were unknown pulled bullets recieved in trade, so load development was nonsensical. They look and weigh just like the .311 speer bullets I have, so by some miracle this is the load of all loads I can do it once maybe twice more.... the only two intentions here was fire forming and boy trigger time...... found 3 Hornady 150s with cannalure in the pile, set those aside for another day... 20240222_153001.jpg
 
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