I got the following weird case necks (almost a flat spot between the shoulder and neck)from my Remington Model 14A in .30 Remington:
Load was a 170 gr. Core Lokt in new Rem. cases with 33.0 gr. of W748 lit by a CCI 250 primer. Velocity was a consistent 2000 fps with good accuracy.
Primers were slightly backed out, too.
What's the diagnosis, docs?
[This message has been edited by John Frazer (edited 02-11-2002).]
I wouldn't worry about it if all else is OK, it looks like the chamber was made with a non-standard reamer. This does not look like damage to me.
I would neck size to just above the top of the chamfer, and go about my business. When the cases get hard to chamber I would full-length size then anneal.
Don
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"They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety."
- Benjamin Franklin, Historical Review of Pennsylvania, 1759.
I do agree the headspace should be checked in any used rifle.
It looks to me like there's plenty of shoulder left to headspace on, if that's where you are going.
Don
I had never fired the rifle before -- these were the first loads I used. 33.0 gr. is right around the mid-range of .30-30 data for this powder and a 170-gr. bullet.
Headspace was not checked -- in part because .30 Rem. (rifles out of production since 1935) is a caliber for which nothing really grows on trees.
This was new brass run through new RCBS dies which I assume are up to snuff. The run through the dies didn't seem to touch the shoulder, I did it as SOP to true up the necks etc.
I have a couple of boxes of mixed ammo -- probably 50-60 years old. My suspicion from the condition of the rifle and and ammo (they were a package deal) is that someone bought the rifle and a couple boxes of cartridges in the '30s, threw on a receiver sight, and went deer hunting with it for a while, then it ended up hanging on the wall for a few decades. The finish is good and the bore is excellent -- sharp rifling, good crown, etc.
First, the picture shows the shoulder has moved forward a bit. Not much, but some. That's a clue
Second, this is a mild pressure cartridge.
Third, the primer backed out.
Now, if the primer backs out, how can it do that if it was headspaced correctly? If the headspace was correct, there would be no place to go! If there is room, the firing pin shoves the shoulder up against the front, the case grips the walls, and the primer backs out.......
In high(er) pressure loads, the case will then stretch and iron the primer, making it look like a high pressure load.
So, low pressure loads and primers backing out is a dead giveaway. FWIW, Dutch.
First off, when I say headspace, it's the headspace of THIS cartridge in THIS rifle. Second, that much headspace is neither abnormal, nor unsafe. You oughta have seen some of the Norma 7mag brass I bought one time!
Now, back to the symptoms. Maximum Saami pressure for the 30/30 is 38,000 CUP. The 30Rem is in the same ballpark -- though I can't find data. Speer says use the same data, so I'll go by that. Don't know what the PSI limit is, but I'm betting it is below the yield strength of brass, which in my experience is somewhere around 40- 45,000 psi.
Under those pressures, brass doesn't stretch to fill the chamber. Kind of like the P.O. Ackley experiments and the 94 win with excess headspace.
I also don't disagree with the fix. Backing out the dies until the cartridge headspace is correct should do it. Actually, the best way would be to headspace the new rounds off the bullet (hard jam the bullet into the lands to push the base of the cartridge against the breech), fireform, and then set the sizing dies to match the chamber.
Where we disagree is that this load is over- pressure. In my opinion, we just don't have enough information to say it is over the max. pressure for this rifle. Based on my experience, I would say it is below 40,000 PSI, which should be fine. FWIW, Dutch.
My dies were adjusted according to manufacturer's instructions. I didn't notice the shoulders moving.
I do have a set of Stoney Point cartridge comparator inserts so I can set the dies to just bump the shoulder a hair, if that would be a good idea.
With a velocity of 2,000 fps, no problem extracting, etc., I can't imagine that these loads are over-pressure.
John