Was shooting a few nights ago and had gone thru about 100 rounds of 10mm. I was firing my CA89-10 in full auto (in case the gun matters, I doubt it). I was going to do one more mag when the bolt would not close. When I got home I decided to measure the OAL of the rounds in the final mag thinking maybe they were the cause. To my surprise this is what I found: 1.224, 1.228, 1.242, 1.251,1.260, 1.261,,1.261,1.262, 1.265 ( My Redding sizing die may have gotten loose; it's tight now ) The rounds over 1.260 and under 1.240 were the surprise. I got home and started to check all my loaded rounds and found some that were over 1.260 so I reseated them to 1.255. I loaded those but still the bolt would not close. When I take her apart I find a squib! The bullet (180 FMJ ) was fortunately NOT in the barrel! It was right where it would be when chambered. I examined all the brass and found two cases that had vertical splits. I was very fortunate that the last round of the prior mag was the squib. I look into every case for powder drop so I am very concerned how this occured. Any way for this to occur with the proper powder level? Help!