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Old Ammo and Action Designs
RCrosby
Member Posts: 3,808 ✭✭✭
Had an experience yesterday that has me re-thinking my use of old ammo and brass, as well as the (no longer so theoretical) advantages of various action types.
I had a partial box of old Winchester .270 ammo; 100 grain soft point, "SuperSpeed" head stamp and well worn red and yellow box. The 5 remaining rounds (not reloads) appeared to be in perfect condition. Bright and shiny; no sign of corrosion or undue aging.
Curious about velocity I headed down back with chronograph in one hand and my near mind Mannlicher Schoenaur 1952 in the other.
Velocity averaged 3,458. Only problem was that the touching off the last round resulted in a sharp stinging sensation across my forehead.
Of course I was wearning safety glasses and ear protectors but the surprise was most unpleasant to say the least.
I packed up my gear and headed back to my shop. Discovered 2 things.
First, one case had split just forward of the rim, and second, the 1952 action did little if anything to protect me from the hot spit of fire and brass. Except for the 2 locking lugs and the ejector that pretty smooth bolt does nothing to interrupt the flow of hot gas back through the action and out the back end.
I saved that one case, crushed the others, and now am rethinking my use of a quantity of old SuperSpeed .257 brass that I have, as well as the M.L. itself. Thinking of trashing the first and selling the second. Had that case let go in my Ruger 77 I don't think the outcome would have been near the same.
I had a partial box of old Winchester .270 ammo; 100 grain soft point, "SuperSpeed" head stamp and well worn red and yellow box. The 5 remaining rounds (not reloads) appeared to be in perfect condition. Bright and shiny; no sign of corrosion or undue aging.
Curious about velocity I headed down back with chronograph in one hand and my near mind Mannlicher Schoenaur 1952 in the other.
Velocity averaged 3,458. Only problem was that the touching off the last round resulted in a sharp stinging sensation across my forehead.
Of course I was wearning safety glasses and ear protectors but the surprise was most unpleasant to say the least.
I packed up my gear and headed back to my shop. Discovered 2 things.
First, one case had split just forward of the rim, and second, the 1952 action did little if anything to protect me from the hot spit of fire and brass. Except for the 2 locking lugs and the ejector that pretty smooth bolt does nothing to interrupt the flow of hot gas back through the action and out the back end.
I saved that one case, crushed the others, and now am rethinking my use of a quantity of old SuperSpeed .257 brass that I have, as well as the M.L. itself. Thinking of trashing the first and selling the second. Had that case let go in my Ruger 77 I don't think the outcome would have been near the same.
Comments
Thanks for writing.
Was the split parallel to the base and rim or did it run lengthwise with the long dimension of the case?
Was there significant debris on the boltface?
What did the face of the case rim look like, was there any shiny marks or small gouges? What did the firing pin mark look like on the primer?
Thanks.
Split runs front to back, about .2" long and starting that same distance from the rear of the case. A little soot at the front end (approx. .1" blot) and to the rear the soot mark spread out about 1/4" to either side of split. No sign of any debree on bolt face, other than the soot. Nothing that I associate with high pressure signs; primer was flattened, but not excessively so. Looked perfectly normal. No sign of gas leakage around it. All leakage clearly came from this small, almost dumbbell shaped crack. (i.e. approx. .017 wide at the center and openning to approx. .045 at either end.) Firing pin indentation appears normal and no shiny points or scratches that I'd expect if pressure had been excessive and there was any brass flow into various irregularities in the bolt face.
Thanks for your interest and questions.
It sounds like a plain old fashion case failure whether due to metallurgy or some unseen fault in the extrusion, who knows. Keep the case on your reloading bench.
Test the .257 brass, it may be O.K.
Far be it for me to tell you what to do with your rifle. I've fired thousands of rounds through several that I've worked with and never had a problem, ever. But that's not to say that the next time may be the one time. Personally I think it's the brass and you won't or shouldn't have any other problems if you use new brass.
Best.
Nononsense, I appreciate the advice. Doesn't make much sense to spend all kinds of money on scopes, chronographs, triggers, etc. etc., and then give up a beautiful rifle rather than invest in some decent brass. Just one of those ever present variables I tend to ignore until they make a difference!
Great discussion, all around.
Thanks all!