Thanks everyone for your help. The rifle in question is a mod 70 mannlicher style stock, probably made in the early 70's, inherited by my father in-law. He lives in Tacoma and came out for a visit, so we loaded some cartridges as I already have .300 dies et al. He had never fired the rifle before.

Based on all your help, I have to assume the problem is excess headspace...

As previously mentioned, the "pressure" problems also existed with factory loads. Additionally, the factory loads did not create these indications in my Browning, nor did the handloads, or the reloads.

ElDegeullo, is it possible for the problems you describe to occur with factory ammunition? These cases showed the same "wear" as the reloads, whether they were resized or not.

Thanks again everyone.

CE

What eldeguello said...

You only want to set your case shoulder back far enough to allow for easy chambering- no more than .002"-.003" Using a FL, or evenworse, a Smallbase resizing die screwed all the way down will shorten the life of your brass.

Rifles that are within saami specs can vary significantly in chamber dimensions- it only has to be somewhere between a Go and No-go headspace guage.

I have swedish mausers that will swallow a SAAMI field guage for breakfast, but have no problems with brass seperating for a few reasons-

1. SAAMI specs are not the end-all-be-all of cartridge specs- they just allow American manufacterers to operate without being sued out of existance by making standardized ammunition and rifles.

2. Excess headspace has to be pretty excessive to be a real problem. After the first firing, the brass will stretch to fit the chamber- youget into trouble when you lean hard on your rockchucker to get the case back to SAAMI specs- the next firing will stretch te same bit of brass that has already been stretched, causing increased weakenss and in extreme cases, caseheadfailure. Just set the die up so it kisses the shoulder, then try chambering the brass with a stripped bolt- continue sizing it down until you can chamber it with minimal resistance.

3. The brass has a bit of springiness to it. When the hot brass expands to fill the chamber, it also shrinks back a little. This is why you can kneck size a case and still chamber it. Though the amont of stretching will eventually catch up and you will need to FL size it after firing a couple of times.

IF there is a little slop in your chamber, to the extent that the shoulder moves forward upon firing EVEN IF THE HEADSPACE IS CORRECT (ie., bolt-face to cartridge belt cut, which is the headspace measurement on a belted case!!) it will cause the case to stretch and an incipient separation to begin. How many reloadings afterward it will stand before the separation is complete depends on the hardness of the bras, etc. etc. I have a 7 Mag. that has this problem. Headspace is correct, BUT the shoulder moves forward because the bolt-face to shoulder dimension of the chamber is sloppy! So I never set the shoulder back when sizing, but the cartridges invariably have a thin spot just ahead of the web due to the first shot! So they are already a little weak.

Many a belted magnum's chamber was cut a little too deep, but the cut for the belt is still within specs. It would not hurt for you to have the headspace checked, it is a simple test and won't cost much. I have seen vbery few elted magnums in which the bolt-face to belt cut edge was too great, but it is of course not impossible. Please do get it checked, and let us know if you really have excessive headspace or not! Then at least you'll know if the barrel needs to be set back and the chamber recut.

( A little comment on headspace. If headspace is actually excessive, quite often the cartridge will enter the chamber too far for the firing pin to hit the primer hard enough to fire it. This is especially true of push-feed actions! If your rifle is giving a good indentatioon to the primer, I suspect there's NO HEADSPACE PROBLEM. But have a gunsmith check it anyway, to remove all speculation.)

This is obviously a head space problem.

The solution I would have is to buy brand new brass and only trim them to length. Find a box of throw away bullets and load them very light. Shoot them at a burm or something and then going forward only neck size this brass about 2/3 down. You will have "fire formed" brass for this specific gun. Only use this brass in that gun.

This should fix your problem.

If you still have head space problems, then take it to a gun smith and have them see if the problem is fixable. Would probably require a new barrell, or posibly a custom bolt to fix.

This is obvoisly NOT a headspace problem, if the shoulder on your brass is moving forward, but the bolt face to belt recess shoulder is giving the correct support to permit your firing pin to indent the primer corrrectly in this push-feed action!! It WOULD be a headspace problem, however, IF IT WERE A RIMLESS, NON-BELTED CASE and the shoulders were moving forward on firing!

Despite this technical point, the solution recommended by speyrjb is correct, JUST SIZE ABOUT 2/3 of the neck after initial firing!!

HOWEVER!! IF you wanted to really go to the trouble to find out if what we are talkng about is correct, you could pretend that your rifle is chambered for a rimless NON-BELTED bottlenecjk case, and, using a .338" or .358" expander ball, neck one new case up, then neck it back down to .30, LEAVING A FALSE SHOULDER ON THE NECK, the location of which you determine by screwing the sizing die out about 1/4", then screwing it back in about a quarter turn at a time while continuing to try to chamber the case each time you move this false shoulder back a tiny amount, until you get to the point where you can just close the bolt on this case with a little force. You now have a "correctly heaspaced" piece of brass, which is headspacing on the false shoulder, not the belt!!

Next, after you know where the false shoulder must be, put one like it on all the other cases and size them to where they can be chambered but just barely! Now you have some cases with "proper headspace", and they will not stretch when they are fired for the first time, nor ever aftward, so long as you NEVER LET THE FULL-LENGTH DIE PUSH THE SHOULDER BACK AGAIN AFTER YOU HAVE FIRED THEM ALL!

This is how I make cases for the .338 Gibbs, for example, using .35 Whelen cases, necking them down to .338 until they will just chamber then fireforming the full-size, .454" diameter, 35-degree Gibbs shoulder onto them!

(In my experience, the liklihood of having a sizing die that is out-of-spec is a lot higher than buying an American made rifle that left the factory with excessive headspace, or a modern-made American rifle in a caliber like .300 Win. Mag. that developed excessive headspace after it was purchased!!)

Let us know how this turns out???

I think it's absolutely amazing that a person can be so expert as to declare something like "This is obviously a headspace problem" without ever examining the gun, putting a gauge in the chamber, or even seeing one of the suspect cases. Yet the idea that, if it IS a headspace problem, a new barrel or worse, a "custom bolt" (Give me a break! For a post-64 M70 Win.? Even if you could find such a critter, that'd cost more than the rifle!!) is the solution! If it IS excessive headspace, the solution is easy: Just set the barrel back one thread and recut the chamber!!