I HAVE A PROBLEM.. I START WITH 300RUM BRASS(REMINGTON) AND LOAD THE CASES WITH 90 GRAIN OF BMG 50 AND ADD (150) GRAIN FMJ TO TOP OFF THE ROUND. THEN SHOT THESE TO BLOW THE CASES TO THE NEXT SIZE. THIS IS THE 3rd FIRING OF MOST OF THESE CASES. WE ARE DOING DIFFERENT LOADS IN .5 GRAIN INCREMENTS FROM 92.5 GRAINS ON UP USING H1000 AND BERGER 185 GRAIN HP BOAT TAILS. WE HAD SOME CASES SPLIT ABOUT 3/4" FROM THE BASE OF THE BRASS. AND HAD SOME FLATTENING OF THE BASE AND PRIMER. WE ONLY HAD 2 SEPARATE CIRCUMFERENCE WISE BUT SEVERAL MORE HAD A NOTICEABLE RING AROUND THE BRASS. TOWARDS THE END WE WERE SHOOTING A-MAX 178 GRAIN AND THE LAST LOADS WERE IN THE 97.0 GRAIN OF H1000. ALL OF THESE ARE LOAD DATA FROM THE 300RUM DATA. WE CANT FIGURE OUT WHY THE SPORADIC SEPARATIONS IN THE LOWER GRAIN LOADS AND THEN ON THE HIGH END THE CASE SPLIT JUST BELOW THE SHOULDER . WE HAVE BEEN DOUBLE CHECKING THE LOADS FOR SAFETY (POWDER) . WE CAN SHOOT 15 ROUNDS AND NOTHING. WWE HAD ONE RING OUT AT 93.0 GRAINS AND ANOTHER AT 94.5. SEVERAL MORE SHOWED I GUESS WHAT SHOULD BE STRESS RINGS. THEN AT THE END , THE ONES THAT RUPTURED RING WISE JUST BELOW AT THE EDGE OF THE SHOULDERS. 3 OF THESE ONLY ONE ACTUALLY RUPTURED. BUT A DEFINED LINE IS VISEABLE. WE ARE BELOW THE MAX ALLOWED FOR THIS LOAD. UP TO 100GRAINS OF H1000 SHOULD BE ALLOWABLE IN THIS ROUND. SAFELY !! ANY INPUT OR ADVISE IS WELCOME. THANKS
COULD POSSIBLY THE SLOWER BURNING POWDER BE CAUSING THE CASES TO DO WHAT I DESCRIBED? NOT GETTING HOT ENOUGH TO MAKE THE CASE FLOW LIKE IT SHOULD ? THANKS
My understanding is when brass cases are fire-formed with light charges or real slow burning powders, the weak areas of the case stretch first. Better to fire form with a stiff charge of a faster powder. I have not seen the load data for the 300RUM but I would stick to the faster powders listed for it. I would even consider the 4350s if they are listed. You may even try the cream of wheat method w/bullseye or 700X. Fred the Wildcatter explains it at his website, you can link up thru Varmint Als I believe. He fire-forms for the 340 Weatherby this way. sure-shot
Check your brasses specs, especially at the web(where the case body starts) Once in awhile Big Green or WW puts out a undersize lot of brass. Check your chamber's specs also, was this a re-chamber job or complete re-barrel? Just some more angles I thought I might throw for you. Good shooting, sure-shot
