7.7 Arisaka Peccadillos

[fourarmed]

Been fooling around with a 7.7x58 Type 99 that my dad sporterized years ago. I don't know why he did it, other than boredom -- which is the same reason I'm messing with it. It slugs .319 with .303 bore near the muzzle, which gets larger near the chamber. The chamber neck will take a .348 plug gauge.

It doesn't shoot worth a hoot with .312 jacketed. I'm considering trying 8 mm cast bullets in it. I have some brass with .010 neck thickness, so I think I should be safe with .323 boolits.

I reformed some 8 mm brass for it using Unique and buckwheat, and it cleaned the bore up to the point that I actually get white patches out of it eventually.

Anybody have any similar Jap tales or advice?

[Larry Gibson]

I've cast numerous Lyman 323470s and 323471s for use in a couple similar groove sized 7.7 Japs. Sized and GC'd in .321 H&I dies. The rifle owners worked up loads with 4895 + dacron filler and were quite pleased with the accuracy. So pleased they bought their own moulds and sizers.

[rbuck351]

Both of mine have a groove dia at .316. The shoot ok for hunting using .312 jacketed bullets but I'm trying to decide how to get a boolit about .317/.318. I have an old Winchester mold for a 32 cal rifle that i'm going to try sizing to .318 to see if it still has lube groves. I have to make a .318 sizer if I can get the time.

[john.k]

if you dip lube before sizing,the grooves are preserved ....although 321 down to 318 isnt much of a reduction ,and will probably be OK.

[rbuck351]

Glad you reminded me of that. I forgot about filling the lube grooves first.

[Rapier]

Luckily mine shoot 180 grain .312 J bullets OK, with 4064 and has a chrome bore. I gave up on RWS brass, too soft. I just fire formed and trimmed 06 military brass. Being an original 99, it is not shot much

[fourarmed]

Took my six cases with the .010" neck walls, and loaded the SAECO 81 boolits sans gas checks ahead of 10 grains of unique. Three of them went in an inch at 68 yards. Now if I could just remember what I did with the gas checks.

[TCLouis]

I have shot two of them.
One was sporterized and would work with .308 diameter bullets and decent enough with cast I carriend it hunt a couple of times with a cast load. Hunting, not shooting anything except a couple of rocks in desperation as I left.

The other I shot the best cast boolit group I have ever shot at 50 yds/open sights.

RD GC boolit launched by 10B101

Gun had the worst trigger I have ever pulled which forced concentration and may have forced good shooting/small group.

[Japlmg]

Use flat base bullets.
Metford rifling does not like boat tail bullets.

[murf205]

Attachment 313691 My Arisaka 7.7 has a bit of a pitted bore. I am sure that it was used with mercuric primers and my dad got it while he was in the Pacific Theater at the close of WWII on an island called Eniwetok. It still has the Mum on it. The salt air contributed to the pitting, I am sure. This photo is what full throttle 180 grs Sierra's and a steel butt plate will do from the bench.

[fourarmed]

Shot it at 100 with the gaschecked SAECO and 19 gr. of 4759. All went in 2". Now I'm out of gas checks and am going to try them bare bottomed.

[Harter66]

I have a 38& a 99 "in process" I guess is the right wording.

Both are grossly over sized but the type 38 is 95 yr old. The NOE 270-140 and paper patched 266469 show some promise. It needs a .272 which is a long way from even to .268 it should be .

The 99 is cut on but has good sights on it . I won't get into my dumbness but it slugs .316×.310. It needs a .318 cast which works out as I needed a .318 sizer for a x39 paper patch I had for a while. I was surprised that it was so easy to squash a jacketed 8mm SP down and that it actually stayed at .318 .

Im using a 8×57 neck die w/o an expander as of now . Necked 8×57 fits fine and seems to HS fine . No 8×57 so no problem there .

The Lee 323-175r2 has sized down fine for 32 Rem and down further for the the x39 I haven't shot anything in the 99 except Grits to shape a couple of 270 cases and find a true chamber length .

[lead collector]

Never spent a lot of time with either of my Jap rifles. The 7.7 showed good accuracy at 50 yards with the NOE 316-299 bullet, and around 12 grains of Unique. I never got around to shooting it any further out.
The 6.5 shoots way high at 100 yards, and I have to stack targets one on top of the other, and aim at the lower, and record the hits on the top one, to hit with it.

[Bigslug]

Other than being Japanese, it almost sounds like you have a .310 Martini Cadet barrel. My .32-20 (.310 Magnum) conversion BSA groove diameter is .3185". First custom mold was an LBT at .320"; second is the Accurate 32-155D set to drop at 321" -.322". You'd likely want gas checks and possibly more weight for your application, but it may be a place to start.

Have you pound-cast the chamber end yet?