Hi. I am new to reloading. Starting with 9mm. I picked up RMR brass plated round nose heads, and some CFE pistol powder. I followed the hodgson LRN data since I can't find RMR, min load is 4.9, max is 5.6, I settled on 5.2 since any inconsistency in powder measuring would still fall within that range.
I tried 20 rounds in a G17 with a Patmos arms upper (might be stock glock spring). Loads worked well as far as during and recoil. Loaded 200 more, checking powder consistency every 20 or so. Theirs 50 with the stick glock upper and it was a failure. Loads felt weak, and couldn't recoil. Other than the upper the only thing I changed was seating depth by about 0.010 inch. Could that difference in seating depth be that drastic? Has anyone tried to calculate figuring out the distance from the tail if the bullet to the end of the shell vs COL?
When shrinking your COAL by a hundreth of an inch it is best practice to drop your powder charge by at least a few tenths of a grain and recheck for high pressure indicators.
That being said, it's been my experience than shrinking your COAL is NOT a reliable way to increase slide cycling reliability (increase recoil). If your loads are feeling weak and barely flopping out of your ejection port or even stove piping, you need to either, 1) load hotter, or 2) lighten your recoil spring.
If you don't have a chronograph yet, it would be a worthwhile investment as it will give you hard metrics and make your reloading endeavors a lot easier to manage.