Cases cracking in type 30

Arisaka, Murata, Siamese, Korean, and North China Rifles
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nrobertb
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Cases cracking in type 30

Post by nrobertb »

Lately I've had a problem with Norma 6.5 Jap cases cracking in half about half an inch above the rim. They've been previously fired a couple of times with mild handloads. Is this indicative of a particular problem with the rifle?

72 usmc
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Re: Cases cracking in type 30

Post by 72 usmc »

After 3 or 4 reloads I toss the brass. I let the range rats take and rework or do as they like with it. Maybe a batch of over hard brass? You can anneal the brass because it is getting brittle. Most Arisakas have generous chambers and the brass gets worked hard if full length resizing. On mine (Type 38) I fire form the first round, than just neck size. But you have to mark each box for that specific rifle. And mark Neck sized, the load and grain used on the box. I do not anneal, too lazy. I toss brass after a few reloads. Five is tops for me. Arasaka 6.5 and British 303 is sometimes overworked in the chambers and full length resizing beats up the brass. So do you have enlarge fired cases? The body of the case splits, that's bad, or just the neck? I have new old Yugo 1950 8mm Mauser garbage brass that is aged and hard that gets body case splits/burn cracks. Brass is just too old and aged. Generally Norma is OK brass, expensive, I use Prvi but do not go more that 5 reloads on a case. I trim, but never anneal.

https://gundigest.com/more/how-to/brass ... king-point

https://www.handloadermagazine.com/anne ... ifle-brass

my 2 cents: Norma is good brass, but is softer and has thinner case walls. How enlarged are you cases after firing in comparison to a new, unfired cartridge. If you have a generous chamber, consider a fire form and neck resize. Or get into annealing.
So if your fired case is a fat boy see this old post. https://forums.gunboards.com/showthread ... fle-6-5X50
Screen Shot 2020-06-20 at 8.48.11 AM.png
You may also want to try some Prvi brass -- also good brass. a final reference:
https://www.capitalcartridge.com/Reload ... -s/253.htm

Rapidrob and ammolab are the big time reloaders, lets see what they think. They are experts and most likely think I am crazy for tossing my brass.
Is it possible to have some photos of the split fired cases?
Last edited by 72 usmc on Sat Jun 20, 2020 9:51 am, edited 1 time in total.
To old to fight and to old to run, a Jar head will just shoot and be done with you.

DaleH
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Re: Cases cracking in type 30

Post by DaleH »

Yes, sounds to me you are pushing the shoulder back too far when full-length sizing, then it is expanding and moving forward to fill the generous chamber. This ‘pulls’ the brass from the rim area and causes the case separation. Some, myself included, use a hook type tool to help identify any ‘step’ felt deep down inside the case and yes, toss before issues. And neck-size only.

On rimmed cases such as the 303 Brit or Ruskie -54R, there is a super cool trick of putting a tiny dental elastic up against the rim on the 1st firing, that forces the head of the rim against the bolt so the case flowe to fill the chamber going forward. Then neck-size from there. That works slick in my 91/30.

72 usmc
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Re: Cases cracking in type 30

Post by 72 usmc »

Lately I've had a problem with Norma 6.5 Jap cases cracking in half about half an inch above the rim.
I thought a case split, but after reading your sentence again, I now think you mean you have this problems shown below.
Brokencases-300x224.jpg
Brokencases-300x224.jpg (16.53 KiB) Viewed 531 times
That is way over worked brass. I would toss it and get new brass. I am surprised you do not get gas back in your face!

The cartridges have been FL sized one to many times. Isn't it fun to get the stuck case out of the chamber? Check if you have Fat Boy cartridges after the first fire and you might consider checking the rifles headspace. see this to read your brass.
https://sierrabulletsblog.com/2015/08/1 ... agnostics/

Check for excessive head space by placing scotch tape over your case head and see if the bolt or breach will close. Or use the poor boy method with craft solder crush. Maybe you have a generous chamber and you got a larger headspace around .040 thousands or more. Then you need to fire form the brass and neck size your brass ---toss it after 4 firings. Think safety, brass isn't that expensive :lol:
Poor boy Method of Headspaceing

Now you can use the Poor boys headspace test :lol: It only provides a general idea. You go to Hobby Lobby or Ace and buy some thin craft solder. Not the thick normal solder.
1) Clean the bolt, chamber, and barrel of the rifle. Keep the bolt assembled.
2) Obtain or make a 6.5 Dummy round. Make sure is a new cartridge and OAL is the same as the live ammo. Mark the tip and pull it, dump powder, and drill primer. Replace the bullet tip to the mark and measure OAL. Is it the same? Do not use a live round in the house. Or use a new live round at the range DANGER :doh:
3) Take the dummy cartridge and place it in the chamber
4) Point the rifle down with the open bolt to the rear
5) Take a length of craft solder and carefully place it over the back of the cartridge. It must lay across the entire cartridge back. It can be half moon shaped so it touches both ends of the cartridge.
6) Slowly close the bolt down onto the craft solder and the bolt face will smash flat the section of solder against the back of the cartridge case.
7) Slowly open the bolt in order to save and remove the flattened piece of craft solder.
8) Do this process three times with a new section of thin, craft solder and get an average of the headspace gap between the bolt and cartridge. Are your measurements around .011- .015 or less? You most likely are OK. You are within hand grenade range for a half as... sample attempt at headspace. If your measurements exceed .015 and are something like .025-.045 you best buy a real headspace gauge and do a correct headspace test on a field gauge and see if the bolt closes on a REAL FIELD reject gauge.

Now this is a poor boys test, not really accurate, but it will give you a general, crude idea of where the rifle falls. Below .011 you are good.
To old to fight and to old to run, a Jar head will just shoot and be done with you.

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nrobertb
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Re: Cases cracking in type 30

Post by nrobertb »

Yes, they cracked in half like the photo above. Thanks for all the good replies. I will be neck sizing only from now on. As far as not getting gas in the face, those two big holes on top of the receiver really do their job!

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Re: Cases cracking in type 30

Post by slowbob2 »

Norma cases are made way too small at the case head . You will always get short case live if you do not neck size . Also most Type 30 rifles had their chambers reamed out larger after problems with chambering and extraction in the 1905 war . Case swelling at the side is not a headspace problem . Just use cheap Lee 6.5mm Swede dies cut off to just neck size . Just backing off 6.5mm Jap dies will not fix it . Also T-30 rifles tend to have about .268 + groove barrels and like long flat base bullets for accuracy .

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Re: Cases cracking in type 30

Post by 72 usmc »

Slowbob could I just use a Lee collet die for a sweet Mauser 6.5x55 to neck size????

Like this one https://leeprecision.com/collet-die-only-6.5x55.html
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Re: Cases cracking in type 30

Post by slowbob2 »

I never have used one , but if you get it to resize just the neck it should work . The cut off standard die is best as it will still bump the shoulder back just a bit if it is needed after several firings , without making the case smaller on the body .

72 usmc
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Re: Cases cracking in type 30

Post by 72 usmc »

I have never done this. So approximately where do I cut off the die? How many treads down from the top. I Assume I am just using the die top to form the case neck and shoulder. Is the cut critical? Or can I leave about an inch?

Ya, you are talking to a rookie reloader. No fancy stuff and a RCBS JR press. :oops:
Screen Shot 2020-06-30 at 10.08.12 AM.png
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Re: Cases cracking in type 30

Post by slowbob2 »

The lenght is not critical , but I like my stuff close . Just measure from the base of the neck to the base of the rim on a 6.5 Swede case and Jap case and cut of that amount [ plus an extra .050 or so ] from the Swede die . Be sure to bevel the base of the die at the cut so you do not leave a sharp edge that could scrap the case when used .

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Re: Cases cracking in type 30

Post by 72 usmc »

Thank You :clap:
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Re: Cases cracking in type 30

Post by slowbob2 »

To be clearer , use the difference in the measurement as the amount to remove .

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