what went wrong

[charlie cleveland]

the 10 ga loads were taken from lymans 4th edition reloading handbook. the load i chose was a2 1/4 ounce load. the the hull used winchester polyformed case..paper base wad 6 point crimp...powder was blue dot 43 grains primerwin. 209 one rem sp 10 wad... velocity 1193 pressure 9600 lup. the hulls had only been reloaded one time actually 2nd time factory loaded first time. after the mishap i had with them i fired 3 factory loads thru gun and examined hulls they were in good condition. i will go back and check my reloading teniques i could have done something wrong.im very carefull with my reloading all of myweights were weighted on good scales. hope i can find out what went wrong thanks charlie