Headspacing a Type 38 Arisaka?

Drachenblut

Drachenblut

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Hello Gents,

I am wondering what is necessary to headspace a T-38 Arisaka? I have heard of go-no go gauges but I am unsure how these would work for this caliber? Does it have to be custom to the caliber?

I have used feeler gauges in order to check the headspace on my Martini-Enfield, but that will not work for the Arisaka.

How much do gunsmiths usually charge (I am in the central-south Alberta region) in order to check to see if a rifle is safe to fire? What is involved in such a "check up"?

What gunsmiths can you recommend in this area? I have heard of a gentleman in Torrington, 35 km from Olds who does rifles primarily. Does anyone know of him or have his contact info?

Many thanks,
Drachenblut
 
Drach, there are days on which I curse the memory of whatever character it was who started all this guff about the utter criticality of perfect headspacing.

For one thing, with rimmed cases, it just ain't all that critical. The Arisaka uses semi-rimmed cases; the rim prevents the case going too far into the rifle, so that's 2/3 of your problem settled. If there is extra space at the FRONT, the case will just expand and fill it. Then you can neck-size safely.

Got a really decent vernier calipre? Then go to your local machine shop and get a little strip of PLASTI-GAUGE. Cut off 7/16 of an inch of the stuff and stick it to the back of a round, then carefully feed the round through the magazine, onto the boltface, and close the bolt. When you open the rifle, the Plasti-gauge will have spread somewhat, so you measure the new width, look at the little chart and you know how much space there is BETWEEN the bolt and the rim. Plasti-gauge is used in industry for fitting bearings in aircraft engines, turbines and other precision equipment. It works fine. I have used it at -37C for fitting bearings to a Climax C-66..... and it ran continuously for the next year with no hassles. Works fine on rifles, too, and it is much more precise than the old "piece-of-a-toothpaste-tube" that we used to use.

But if the boltface has the round up against it and the extractor is holding it in position and the rim prevents it from going into the barrel...... it's safe for a hipshot test.

Curse SAAMI, anyway!

Hope this helps.
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Headspace

Oh, Oh! Someone has released headspace monster and has incurred the wrath of the Mighty Smellie.

However, I have to agree with him. Many of the people here get in a frenzy about minimum headspace, and predict dire consequences to anyone who is foolish enough to fire something with less than perfect headspace.

Most of those "check the headspace" posters have only a faint idea of how headspace is checked. For some, it seems to be a contest to see how many posts they can make, and "check the headspace" is a way to add another one to their total.

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Interesting, I did not know headspace was such a moot point. I appreciate the information! Does anyone know what the headspace of the Arisaka is supposed to be?
 
...yeah, I saw this and thought similarly as smellie.

I'd believe that checking headspace on such an unusual rifle might be a long and tiring journey, after which you're (IMHO) likely to find that shooting the thing is as safe as anything else. Honestly.

Like, is it really rough? Is it really rusty? Has anyone you know fired it lately? Can you compare fired cases to unfired rounds' cases and see if the fired ones are extremely different in shape than the unfired one... and I mean extremely...? Is it in good shape, or recently refinished?

If you're careful, and wear heavy gloves, a couple of mack jackets, and face/eye protection, I'll bet you'll be able to safely collect a set of fired cases to compare to unfired ammo.

...are you certain of the rifle's calibre? It could be a 6.5 or a 7.7 you know...
 
Hi again drachenblut, I guess my above comment might be a bit sarcastic...

I also think headspace is really important if the rifle's worth the trouble, or if one believe's it to be. And it is a rifle/cartridge specific measurement, so the theory about this relationship between rifles and cartridges is similar, but the means to measure it changes.

Perhaps get someone to machine you up a set of go and no-go gauges for this rifle? (Damn, there I go sounding sarcastic again! Not what I intended, but I'll bet the gauges for this rifle are tough to find in Canada...)
 
The measurement is going to be a dimension from the head to some point on the shoulder. The actual number is meaningless, except in reference to a gauge.
The chances of finding a gunsmith with 6.5 Arisaka gauges are, well, slim at best.
The method Smellie has suggested will give you an idea how much breezeway there is between the casehead and the boltface. Offhand, if is less than 6-8 thou, I wouldn't lose any sleep.
Here is another quick experiment you can try - fire a primed case. The primer will be protruding. Measure the protrusion. This will give you an idea of how much of a gap there is.
Or, fire the rifle with a string. Section some caseheads, see if there are any incipient separations.
If you really want to get a gauge, a Field gauge is the one to try.
Something to think about - let's suppose that the rifle has really, really, excessive gap. What are you going to do about it?
Easy. Handload so that the cartridges are a perfect fit. Not hard to do. And if you are going to be shooting the Arisaka, you will likely want to handload anyway.
 
At one of the Shilo matches some time back, fellow was there with a Garand with one of the USN chamber inserts in the thing, firing issue 7.62NATO ammo. Halfway through the match, his rifle shot the chamber insert loose and out, but he didn't see this, so he just kept shooting. He shot the last half of the match with 7.62NATO ammo running in a .30-'06 chamber.

That is HALF AN INCH of excess headspace.

That is more than 150 TIMES the "hide-under-the-table-it's-gonna-blow-up" absolute maximum.

All that happened was the 7.62 cases expanded at their front ends to mostly fill the chamber. At the rear end, they were held in place by the fact that the 7.62 has a little less body taper than the '06, so they were squished into the chamber by the bolt and held solidly at the rear end.

No big fireball. No spare parts cluttering the landscape. No ambulance. No dustoff with medics pouring plasma into both arms. Just funny-looking brass.

If the cartridge is held solidly against the boltface, or with a minimum of space between the boltface and the back of the cartridge, you're pretty safe. Any expansion will be at the front, which is where it is with any rimmed or semi-rimmed case. Expansion at the FRONT is normal; happens every time you pull the trigger.

On the 6.5 Arisaka, the rim revents the round from going too far into the chamber, so all you have to worry about is that space between the boltface and the base of the round. The EXTRACTOR holds that in position if you feed the rifle correctly (through the mag, like any other Mauser copy), so your risks are minimal to start with.

I have a Type 38 Arisaka and brass, until very recently, has been impossible to locate around here. I find that .220 SWIFT brass is a PERFECT fit at rim and base. As well, it is engineered for truly gawdawful pressure levels. Get .220 SWIFT brass, FL size, trim, load and head for the range. Likely it is the easiest cartridge conversion in milsurps that you can think of.

Have fun!

Hope this helps.
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Hello gents,

I will attempt to get some plasti-gauge from my local machining shop in town. I am interested in seeing what headspace I have.

Now for an off the wall topic here, since I have smellie's attention!

I have a Martini-Enfield that spaces 0.10 with feeler gauges. I have lots of brass that looks quite stretched, but nothing broken, and I've only ever had 1 case head separation, that being with a 1916 dated British bullet I fired (it was in my reload box... weird how that happens!). Is this too much headspace, and how can I fix that?
 
What I would do for the Martini is just segregate the brass for that rifle and neck-size only; once the stuff has had an initial chamber expansion it will be headspacing like a rimless round, just with the rim to prevent forward movement. Perfect candidate for neck-sizing.

Works.

Works with just about any rifle, come to think of it. You don't have to worry about ammo interchangeability because you have just the one old carbine..... and no huge worries about hordes of Fuzzy-Wuzzies pouring over the hill to upset elevenses and get messy, sticky blood all over your nice red serge tunic.

Have fun!

That's what it's all about!
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Thanks gentlemen. I appreciate all the wonderful info. Currently, I am buried in a snowstorm, but once I get out, I will get some of that Plasti-Gauge and check the headspace on my carbine. That is, one I have brass to test it with *wink, hint hint*
 
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