Reforming 7.7 Jap from 30-06.....

What do you think.

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I form cases, I have foremd 7.7 Japanease from 30/06 cases. I always start with a forming die. I use the 308 W forming die when forming 7.7 cases. There is an advantage to using 30/06 cases because of the length from the shoulder to the case head. The 30/06 case requires the new shoulder further back by .078” that makes it difficult to use a full length sizing die. If the cases are going to be sized with a full length sizing die I suggest you use new cases.

I will also suggest you not start by full length sizing, I start by adding .010" to the length of the case from the shoulder to the case head. The reason for the additional length is to off set the length of the chamber. If necessary the case can be sized to a shorter length but it is difficult to add to the length.

F. Guffey

Lee dies are good value for the 7.7X58 Jap. I use these dies (minus the decapping rod) to full length size .30-06 brass. Afterward I trim to length, chamfer the case mouth then reload with cast bullets to fire form. Seating the bullet out far enough to give some resistance when closing the bolt will insure the case head is held against the bolt face when fired. Fire-formed cases need only be neck sized there after. Be sure to slug your bore as Jap bore diameters are all over the place. My two 7.7s measure .314 with a .315 throat. It is difficult to measure Jap bores with their "medford" rifling but the throat measurement is most important. I size my cast bullets to .315" to match the throat.

Grafs has Prvi Partisan 7.7Brass. However they are currently out of stock.

I recently ordered some and a die set for an aquaintance fo his Arisaka. Loaded up some beautiful ammo. First shot, hit where aimed. However, extracted case indicated it had been converted to 7.7/06!

Oh well! He was happy! He sold rifle and remaining ammo to someone who liked how it shot!

I am going to be sending you some of my fired brass from my rifle. I hope to get to the post office on Saturday to send them. No charge for the brass or postage. It is my gift. I could not get it out Thursday night because I got home from work too late, and have to get some things done right after work today, but you should have it by early or middle of next week. These are fire-formed to my rifle, and may not be exactly perfect for your rifle. The cases come from Precision Reloading, 150 gr FMJ 7.7 JAP ammo. As I understand it, P.R. is a commercial reloader who gets fired brass from Grafs and then sells the reloaded ammo back to Grafs for retail sale. (Not sure if P.R. gets fired or new brass from Grafs). I have found that in my rifle, the Hornady 150 gr SP and SST ammo is more accurate than the P.R. ammo, but I have not measured the COAL or anything like that. My rifle was brought back from the war in the Pacific by my grandfather who was in the U.S. Navy. I put an S & K scope mount on it for a scout scope and it is a nice rifle to shoot. Using the Hornady ammo, I can hit steel at 200 yards 9 out of 10 times with the scope sighted in for 100 yards, and I think it could shoot pretty flat out to 300 yards if I could see the targets out that far. I've been hanging on to the fired brass for a long time but have not started reloading for it because I do not do any large primer loading. I may get into that at some point but for now, I concentrate on loading 223, 9 mm, 38 and 357 Mag. I think Redding makes dies for loading 7.7 JAP.

I use RCBS 7.7 dies, 06 cases, and lots of lube. Slowly form, trim, then fireform. Works fantastically, and if you wrap a single layer of scotch tape just above the extractor groove, you can mitigate the bulge, if your rifle is prone to this. If you can score some 8x57 brass, they can be run through, and used as is (but a bit short).

Load them up using IMR 4895, TAC, and H-414, and Sierra and Hornady 150 grain SP bullets. Nice and accurate, and what a fine rifle the Type 99 is, love my Arisaka. Good luck.

Double post

Glad they arrived OK. I started pushing the brass cases into that cardboard box and no matter how many I put in there, the box kept looking pretty empty and my bag of fired 7.7 JAP cases kept looking the same as it did before each handful was removed, so I just kept going until the box would not hold anymore. If you are ever going to be down in the south/central PA area, let me know and I will give you a box or two or three of that Precision Cartridge loaded ammo.

Seating the bullet out far enough to give some resistance when closing the bolt will insure the case head is held against the bolt face when fired. Fire-formed cases need only be neck sized there after.

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I could never understand the logic; the reloader is forming the case from a case that has a shoulder that is .078" longer than the 7.7 case lengths from the shoulder to the case head why wouldn't he simply size the case to fit as in form first then fire instead of forming and then fire forming? The last 80 cases I formed I sent to a shooter that lives west of Ft. Worth, Texas. I sent him 20 cases that were minimum length as in .005" shorter than a go-gage length chamber. I sent him 20 cases that were go-gage length meaning when he fired those cases there was no clearance and I sent him 20 cases that were no go-gage length. And on the outside chance he had a rifle with a very long chamber I sent him 20 cases that were equivalent to the length of a field reject length gage.

The no go-gage length cases and field reject length cases would not allow the bolt to close. The go-gage length cases allowed the bolt to close with slight resistance to bolt closing.

When sizing the cases that would not allow the bolt to close I suggested he adjust the die off the shell holder .002".

F. Guffey

I believe the reason for this is if the head space is max or over your not pushing the cartridge forward and getting stretch in the case head when it pushes back to the bolt face. The shoulder will fire form. Then neck size so you won't get case head separation.

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You can say that again

Given a choice I off set the length of the chamber with the length of the case. And then there is the assumption the case is driven to the front of the chamber with the firing pin.

F. Guffey