Capt_C

Glock is doing their corporate CYA-routine. If you're loading near max, based on +P load data, right on the edge of blowing up your Glock, loading 0.01-in deeper could possibly become a safety issue. If you're loading to standard pressure, and also loading a max-pressure load, reducing your OAL by 0.01 could take your ammunition over the edge from standard pressure to +P. I intentionally select slower powders that provide the velocity I want to achieve with a significant margin of safety that I'm not losing sleep over seating depth or over normal variations related to typical powder dispensing systems. I'm not trying to save $0.00000019 per round by shooting smaller charges of faster (higher-pressure) powders. BTW: if you were to measure every powder charge you drop on a progressive press, you will see what variations can occur. If you're loading at max with a fast powder, there is some level of probable risk that your pet load may unexpectedly result in a load that exceeds that published maximum. Also, don't forget, the SAAMI max is based upon an AVERAGE max pressure, not an absolute Max Pressure. Capt_C

Suggest you get in the habit of labeling your powder measure... post it notes and 'skotch tape' are handy... capt_c -c

I'm not loading major, but have been loading since 1972, and I've measured the OAL of quite a few cartridges in that span of years. I can tell you without any doubt that the ogive of even best-quality bullets varies enough to change OAL by up to +/- 0.005. I'm currently loading 147-gr 9mm and set up my seating die for nominal OAL of 1.160... I get a few at 1.165 / 1.167 but all pass my gauge test, plunk/spin test and sig-P320 Mags. Most importantly, no malfs of any kind, Capt_C