Loading LC 5.56 brass with 26 grains of 748 topped with 55 grain FMJ factory seconds from MidwayUSA (assume they are Hornady but I'm not certain) that I just ordered. Using RCBS .223 dies on a RCBS Rock Chucker press. Shooting out of 16" AR15.
Trimmed brass to 1.750". Set seating die to seat bullet to 2.248" (half of cannelure visible). Loaded my first 50 rounds. Noticed on about 10 out of 50 of the rounds that the entire cannelure was above the case mouth. Measured those rounds with calipers and they were 2.265" (would not fit into PMAG). In order to get those 10 rounds down to 2.248" OAL, I had to bump the seating die down a little bit. I ran one of the good 40 rounds through the newly adjusted seating die just to see what happened and it brought the OAL down to around 2.23" (cannelure fully inside case mouth).
There's obviously a variance in the bullets. The ones that are giving me trouble seem to be fatter (less taper) but it may just be an illusion. I only have a calipers. I don't have a micrometer or any other measuring tools. I've loaded thousands of .223 rounds and never had this issue. Bought 1,000 of these bullets from Midway with the intention of bulk loading them. I don't want to have to analyze every round after loading to check OALs. So before I contact Midway for a return, what exactly seems to be going on here? Different length bullets? Ogive? Cannelure position? Picture attached. Not my picture but shows what's going on. Thanks
