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View Full Version : Hot load - split case??


Blaster
July 17, 2011, 11:17
A couple years ago while I was shooting my .50BMG down at the Whittington Range, Raton, NM, I was watching a guy with another bolt action .50BMG. He shot a few times and was then beating the bolt with a leather mallet in an effort to raise the bolt handle to cam the empty out of the chamber to extract it. He finally got that empty case removed with the help of many many hits with the mallet. After checking over the empty, he felt that he "may" have loaded it a little too HOT. I asked if I may have that empty to show someone else. Of course, being another friendly .50BMG shooter, he gave it to me to hang on to.
Here's a picture of the case which is almost split in two. Note in the second picture, the primer is pretty well flattened in the primer pocket. The third photo is that of a tool that can come in mighty handy in the event of a separated case is lodged in the chamber. If you feel it worth while, you should try to buy one of these "broken case extractors" at the next gun show you attend. It's a very valuable tool that can possibly save your range session if you are unlucky enough to experience a separated case. Lesson: don't load em too hot. As one chap said, those .50BMG cartridges being fired are kinda potentially like having a hand grenade right close to your face.
http://img.photobucket.com/albums/v310/bobjan/50BMGstuff001jpg.jpg

http://img.photobucket.com/albums/v310/bobjan/50BMGstuff002jpg.jpg

http://img.photobucket.com/albums/v310/bobjan/50BMGstuff007jpg.jpg

shortround
July 17, 2011, 13:40
"Insipient" case head separation caused, probably, by sizing the case too much for that chamber when reloading.

What happens is the case is shoved forward against the shoulder when the firing pin slams into the primer. As the powder ignites, the pressure starts to build in the inside of the case. The weaker portions like the front of the case and the primer begin to expand, the front of the case into the chamber walls where it adheres because of the pressure, the primer starts to back out until it hits the bolt face. As the pressure builds, the back part of the case, the head, moves backward and begins to stretch at the point where the wall of the case is too strong to expand and grab the chamber wall.

This is the point you see the "crack" on the case in the picture. The case head continues back and flattens the primer, which some will assume to be because of pressure, but may not be.

It also doesn't help that the case is surplus and may have been stretched the first time it was fired in a long head spaced belt fed.

riffraff2
July 17, 2011, 17:48
shortrounds last sentence says it all.

If you are going to get into the fifty game do not try to cheap out on all the stuff you will need. Do not buy once fired mil surp brass. Go ahead and buy new brass. The time and trouble you will save yourself will more than make up for the little bit of money you will save by buying everything at the cheapest price you can find. If you have never fired mil surp ammo go ahead and shoot it in the gun you will be useing the brass in, no problems there. It is the stuff run through a M2HB that will cause the problems.

gates
July 17, 2011, 23:28
sizing.

jerry
July 21, 2011, 16:49
Plenty of the miltary cases were fired out of machine guns with very generous headspace. They will stretch the case down by the head (exactly were the case broke free in the pic).
With the size of the 50 case you can see an indented ring inside the case just above the case head.
Those are the ones to stay away from.
I have about a hundred cases a dishonest guy traded to me when I first started out with the 50.. They look pretty on the outside but--- I won't use them

Jerry

Blaster
July 21, 2011, 17:22
To help eliminate a good portion of the chance of excessive H.S. stretch on the once fired M.G. brass that I have bought, I always use the thin wire hook method of feeling inside the wall of the case for that POTENTIAL case stretch. That method is still far from providing real assurance that the case has not been stretched but it has always been sufficient enough for me - so far.

If I were to sell some of my once fired M.G. cases, I'd certainly sell them with the notice that they are being sold "as is, not checked for case stretch" and recommend each case be closely inspected prior to reloading it.