split 7.7jap cases

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  • Last Post 30 June 2012
ubetcha posted this 04 June 2012

I was shooting my 7.7 Jap today and had some cases split.About six of them.These were mild loads with either a 185gr or 200gr bullet.Any suggestions?

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LWesthoff posted this 04 June 2012

How many times have those cases been fired? Who made them? And when you resize them, are you you using a regular (standard) sizing die, or are you using something like a Lee collet die?

Wes

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ubetcha posted this 04 June 2012

Number of times reloaded unknown as I received them from an acquaintance just after I got the rifle.I have had this rifle for several years but just now starting to shoot it.Cases are P-R,and my dies are Hornady F-L.Another person suggested annealing the cases.These are reformed 30-06 cases

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shastaboat posted this 04 June 2012

I'm sure your brass is getting brittle. I also made 7.7 from 30-06 because I couldn't get 7.7 brass. It is bigger at the head. 7.7 brass is now available. If you use converted 30-06 brass make sure you anneal the shoulder and necks after every 6 loads or so.

Because I said so!

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JeffinNZ posted this 04 June 2012

Yeap, brittle brass. My Carcano dies work the brass so hard I have to anneal every firing or I get split necks and Carcano brass is not easy to find here so I am careful.

Cheers from New Zealand

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LWesthoff posted this 04 June 2012

You can buy 7.7 Jap brass nowadays, and if you want to shoot that Arisaka I suggest you do that. Also, I'd suggest you either resize with a Lee collet die or neck size only and anneal your brass. '06 brass works, but it is NOT a proper fit and if you go that route brass life will probably be pretty short no matter what you do.

Wes

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ubetcha posted this 05 June 2012

Before I invest in anymore dies and 7.7 brass,I will see if this thing shoots good.No need to get all new equipment for something that won't hold a good group.Having never annealed before,what is the step by step procedure.do you anneal before or after sizing.I do think my FL die is set for neck sizing.I do like the Lee Collet Dies.I have one for my 30-30 and 30-06.I have watch some youtube videos on annealing and seem pretty straight forward.I also read an article on using 8mm Mauser brass for forming 7.7mm's

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runfiverun posted this 05 June 2012

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joeb33050 posted this 05 June 2012

The cases in the picture do NOT look like split-necks-that-need-annealing. They are not split to the case mouth. When mine split because they get hard-they split to the mouth. The picture cases look like examples of STRESS CORROSION CRACKING. If so, the 30-06 brass was the culprit. Try some new 30-06 brass. 30-06 brass worked fine for me in all my Jap rifles, including the Pope-Arisaka. joe b.

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tturner53 posted this 05 June 2012

What Joe said. Might be time to scrap that batch of brass. FWIW, my 3 Type 99 7.7s all have huge throats and oversize bores, like .304x .316. You'll likely need a real fat bullet to get good accuracy.

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LWesthoff posted this 05 June 2012

I'm inclined to agree with Joe regarding the cause of the pictured cracks - they are stress cracks (I'm not so sure about the corrosion part). However, I'd still strongly recommend using 7.7 Jap brass. Among other things Jap chambers are at least .007” larger than '06 chambers back at the base of the shell, back in the area where case separations are going to occur. I remember we used to be advised to put a wrap of scotch tape around re-formed '06 cases, just in front of the extraction groove, to help center the case in the chamber.

However, if you DO get a case separation, that Arisaka bolt design will do an excellent job of keeping gasses and other unpleasantness out of your face. I speak from experience, there.

Wes

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LWesthoff posted this 05 June 2012

Sorry - finger stuttered when I punched the SEND button.

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ubetcha posted this 05 June 2012

Thanks Guys.This does help alot.Gives me some options to try.I really would like to keep this as a shooter.I do have some once fired brass from a deer hunting sight-in clinic.They are Federal 30-06.Lwesthoff,I know you still recommend 7.7 brass,but I would still like to use what I have on hand before investing in Jap brass.I my try approx 20rds and keep them seperated from the rest to monitor them.Should I try annealling them before reforming to 7.7?

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ubetcha posted this 06 June 2012

Thank R5R .that a pretty interesting article.will have to copy it for future reference.I did buy a scope mount from Kent Light several years ago to use in IHMSA silhouettes.When I called him he said he will send the mount and when I get it ,then send the money.I thought” WHAT, SOMEONE THAT DOESN'T KNOW ME FROM ADAM IS GOING TO TRUST ME TO SEND MONEY AFTER HE SENDS THE PRODUCT". Very nice person to deal with.I would buy from him again.

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delmarskid1 posted this 06 June 2012

For what it's worth you may have good luck with some fresh GI '06 brass. The webs are thicker and will stand the blowing out at the base. DCM shooters hoard the stuff.

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ubetcha posted this 30 June 2012

LWesthoff I did take your advise on getting 7.7 jap brass.I picked up some loaded rounds of Hornady 7.7's and mic'ed them to the fired 06 brass that I used.There is a difference .The fired 06 brass measured .465 at the web and had a ring just above the web were it was bulged and the unfired 7.7 measured .472 at the web.That bulge does indicate to me that a head separation would happen soon.I will compare the fired 7.7's to the fired 06 brass after I shoot them.The new jap brass does appear to have been annealed also. Thanks for advise for preventing a possible bad occurrence. I'am also hoping that these are boxer primed. It has a PPU headstamp

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