What an interesting place for a case separation...

[jonk]

I was shooting my 7.7 Arisaka this weekend with some bargain .311" J word bullets I got from Wideners a while back, from pulled Mosin ammo. 150 gr bullets, powder charge of 42 gr of IMR 4895. Not a real smoking load, especially given the Arisaka strength. There were no indications of excessive pressure with regards to the primer, or with recoil or report.

Converted 06 brass. It's been fired a few times but not excessively, I'd say 4-5 firings.

I saw signs of incipient case separation on several of the cases after this outing. Usually when I see this it is near the case head, but in this instance it was well forward, about 1/3 of the way back from the neck, or 2/3 of the way forward from the head. In other words, just a bit below the shoulder.

Now, certainly part of the issue is a somewhat sloppy chamber. I'm wondering though, what would cause the case to stretch and start to separate THERE? That portion of the brass should be well glued to the chamber wall when firing. I've been neck sizing this brass only after the initial firing in a full length die, adjusted to just get the neck and not touch the shoulder.

Whatcha all think?

[bruce drake]

4-5 times with full-bore jacketed loads or with cast?

I usually retire my highpower match ammo to cast loads only after 5 loads (3 with my Garand).

I also own several Arisakas (currently 5) and I find that my T99 Arisakas really prefers the cases I make from mil-surp 30-06 brass over commercial brass because the mil-surp brass is thicker and doesn't stretch out so quickly.

Bruce

[nanuk]

an oily chamber, where the neck shoulder is clean and grips tight, but the rest slides back a bit, and the stretch is where the clean chamber ends and the oily chamber begins?

just a SWAG!

[jonk]

It is milsurp brass.

The chamber might have had a little oil in it, but it is highly unlikely. I oil the bores when I shoot corrosive ammo (and remove before shooting) but the Arisaka is handloads only. Meaning in practice, I never oil the bore or chamber.

More or less all J-bullets. The Arisaka is one of the few I've never had much luck with with cast.

[plainsman456]

You might be able to anneal the cases that far back ,they may be just brittle.

[303Guy]

4-5 firings before incipient case head separation? Cases are too dry! The Lee Enfield is supposed to be the one for short case life yet My cases last forever (with normal for Lee Enfield loads). You've probably read before that I lube my cases lightly using case lube (I'm not suggesting you do it - it is a controversial issue, just saying what I do and that it works for me). I think the assessment that the forward portion of the case was glued to the chamber walls while the rear section lost its grip and slid back suddenly. Brittle cases? That too. Maybe both. I should point out that I do not oil the chamber or bore, just the case lube on the case. Either way, why would a case previously fired in that chamber and only neck sized be able to move back at all? It should be fully supported by the bolt face. In fact, there should be a slight pre-loading of the bolt face.

[jwmprock]

06 is a sloppy fit in the Arisaka 7.7 chamber, lucky to get 4 or 5.

[zuke]

4-5 times with full-bore jacketed loads or with cast?

I usually retire my highpower match ammo to cast loads only after 5 loads (3 with my Garand).

I also own several Arisakas (currently 5) and I find that my T99 Arisakas really prefers the cases I make from mil-surp 30-06 brass over commercial brass because the mil-surp brass is thicker and doesn't stretch out so quickly.

Bruce

I ran an experiment year's ago with 20 R-P brass in a bolt action 30-06.
I found them,tumbled them and then loaded them up, then fired them. I then began to neck size them and trimmed every 3rd firing.
I reloaded those same 20 R-P case's,25 time's.With full power load's.

[MtGun44]

You might try backing off your sizing die a 1/2 turn and see if the resized cases will still
chamber, if so they will last longer.

One of the advantages of handloading is that you can adjust your ammo to your gun rather
than make minimum chamber spec ammo all the time and have it stretch excessively in
your (almost always) greater than minimum spec chamber. Zuke is carrying this to the
logical extreme, which is also not at all a bad idea - neck sizing. The 25 loads from a case
is impressive.

If Lee has a collet die for 7.7J, they are wonderful devices and produce accurate ammo that
does not stress up the cases much at all. If I was trying to get max case life, a Lee collet
sizer would be my first step.

The point about .30-06 brass being undersized is another good one, the brass is stretched
a good bit just to start with. I use Graf's 7.7 Jap brass and it works great - but I have not
done a large number of reloads on it, either, probably only 2-3 loadings on the brass so far.

Bill

[303Guy]

... and trimmed every 3rd firing.Interesting. I only ever trim to square the case mouths. When I've trimmed too short those cases stayed that way - 223 and 303 Brit. (My hornet I allowed to grow until they reached the the chamber end where they couldn't grow any longer. I was then head spacing on the case mouth. That only works is no neck sizing is done).

[1Shirt]

Think that there is a case to be made here for a few things. Tend to agree at least in part with 303 Man. Think that seating may be a factor and OAL should be a consideration. Think that neck sizing would probably help. Think that you should anneal 2nd or 3rd. fireing.
1Shirt!:coffeecom

[Dframe]

You might be able to anneal the cases that far back ,they may be just brittle.

That was my thought as well. Also perhaps oil in the foreward part of the chamber. or perhaps the way you are sizing.

[jonk]

For the people who said, "Just neck size," You obviously didn't read my OP in detail. I do neck size.

As for annealing, it's not worth it to me. I find annealing- unless you have a way to truly control and evenly distribute the heat- leads to poor repeatability and a loss in accuracy. I do it for some more exotic calibers, but I have buckets of 06 brass and have no issue just scrapping it if it starts to fail after a few firings.

I had a thought. I wonder if the chrome applied to the bore on the Arisaka extends just that far into the chamber? I'd think this would have the opposite effect, i.e. the front of the chamber would be smoother, but who knows?

[bruce drake]

For my fellow list members. My highpower match load brass (308 Win, 30-06 and 223 Rem) are swapped out at 4-5 loads because I shoot a stiff load. After that they are cast bullet brass and they last for almost forever with the lower pressures.

Bruce

[303Guy]

jonk, I did read it. What you didn't mention is whether or not the sizer die sizes the body at all. I still think it's caused by dry cases but necessarily in your gun. If those cases you are using are range pick-ups then the damage could have occurred before you got them. If they are weakened already then what happens is they grip the chamber walls but instead of progressively creeping rearward with the most creep occurring at the rear with progressively less creep toward the shoulder where it stops, they stop creeping at the weakened point and just stretch there.

[zuke]

"but I have buckets of 06 brass and have no issue just scrapping it if it starts to fail after a few firings."

Then don't worry about our advice and shoot away!
I reload for the 303 EPP's, and I anneal the hell out of the first half of the case because that's where all the brass is being formed.
I use military brass,and reanneal after the first firing to extend case life.
Trim with a LEE case length every 3 firing's which mean's I run them onto that cutter to see if anything get's trimmed off.And most of the time it might be a high spot if anything.
I do that with all my brass,run them into the LEE trimmer to see if there's any high spot's.

[jonk]

jonk, I did read it. What you didn't mention is whether or not the sizer die sizes the body at all. I still think it's caused by dry cases but necessarily in your gun. If those cases you are using are range pick-ups then the damage could have occurred before you got them. If they are weakened already then what happens is they grip the chamber walls but instead of progressively creeping rearward with the most creep occurring at the rear with progressively less creep toward the shoulder where it stops, they stop creeping at the weakened point and just stretch there.

From my OP: I've been neck sizing this brass only after the initial firing in a full length die, adjusted to just get the neck and not touch the shoulder.

If it isn't touching the shoulder, it isn't getting to the body of the case either in any meaningful way, unless I am sorely mistaken on how reloading dies work.

That aside, I would consider your suggestion of lubing the case lightly for lighter loads especially; but this seems a pallative to me, rather than a solution. Normally speaking, you don't have to lube cases to shoot them in a gun, and while I agree with you that the hype surrounding not doing so is overblown, it isn't addressing the real issue.

I said these cases have been shot with mainly jacketed loads, but not solely jacketed. There have been some cast loads that were jammed against the rifling for initial firing after conversion to make sure that the case was fully seated against the bolt face. Ergo, there really is no room to stretch- which is why this has me so puzzled.

For a hoot though, I might try annealing a few just for giggles and see if the issue goes away, or lubing a few with lighter loads.

[303Guy]

If it isn't touching the shoulder, it isn't getting to the body of the case either in any meaningful way, ...Normally I would expect so. I asked only because my 303 Brit die is like that (tapered case). But it didn't seem to cause any issues. In the Lee Enfield, case stretch is a real issue with their flexi-actions. Your issue does seem unusual especially with the steps you have taken to fire-form the cases without stressing the cases.

By the way, light case lubing does not prevent case to chamber wall grip. It does keep it to a lower and more controlled level. The case should therefore settle firmly against the bolt face earlier in the pressure curve. (It might even improve accuracy?)

[handyman25]

7.7 jap is 58 mm long, the 30-06 is 63 mm long. Maybe you have chamber that has no throat and the case is up in the rifling. My way to make the 7.7 jap out of 30-06 would be, first run the 30-06 case over a larger expanding ball, say .358, then size 3/4 of the neck to 7.7 jap and then trim for the proper length and then FL the case to fit snugly in the rifle and load from their. I have a marlin 336 in 35 remington with almost no throat, so I need to be carful about what size bullet I use in it.

[jonk]

7.7 jap is 58 mm long, the 30-06 is 63 mm long. Maybe you have chamber that has no throat and the case is up in the rifling. My way to make the 7.7 jap out of 30-06 would be, first run the 30-06 case over a larger expanding ball, say .358, then size 3/4 of the neck to 7.7 jap and then trim for the proper length and then FL the case to fit snugly in the rifle and load from their. I have a marlin 336 in 35 remington with almost no throat, so I need to be carful about what size bullet I use in it.

I appreciate the suggestion, but I took it for granted that people would understand that the cases are properly trimmed to length for the Arisaka and sized. That's what I meant by 'converted 06 brass.'

I use a Harbor Freight cutoff saw, FL size in the Jap die, then final trim and chamfer No issues so far as it goes, and I use the same procedure for 8mm Mauser and 7.65 Argentine, with neck reaming if needed.