Never heard of it, though mnaybe y'all are getting it all the time and haven't told me. The first time I thought is was a fluke. 20 shots from a G20 pistol with SD of one foot per second. During the string I thought something was wrong with the chrono, because shot after shot it displayed the same number. Then there's the saying; if you test your velocity once, you'll know it. If you test it a second time, you'll never be sure again. Though I never got any error readings, I discarded the data.
So I went out a second time on Saturday with the same load. The CED chrono was unwilling to get any readings from the 30-30 loads I really wanted to test. It's like that sometimes, even with the IR LED screens. But it took readings from the slower, bigger 10 mm bullets just fine. I only measured ten shots this time, so a SD is of little meaning, but the extreme spread was 6. It might correlate to a SD of 1. I don't know about anyone else, and the ammo manufacturers rarely say anything about it, but I've thought I was doing pretty well in the past if the SD was 12 or so.
This is a light load for the ten, getting barely under 1100 fps. More like a 40 S&W. It's 9.6 gr. Blue Dot (checked against a check weight) with new Starline cases, 180 XTPs and a CCI 300, just going by the dimensions in the Hornady manual. Nothing special. This was my starting load, but it may end up a keeper. We'll see. At the moment it's my carry load, with 43 rounds on board.
I know - handloaded ammo for self defense, blah blah. Don't care. I can practice a lot more with this stuff because I can afford a lot of it, and practicing with the same load you carry makes sense. That's what I'll tell the lawyers-- I can shoot this load more accurately and therefore more safely, etc., because it's exactly what I use for practice. I tried some of the hot Double Tap 200 grain FMJ stuff. It's affordable for practice, and while I'm sure it's fine ammo for some guns, my Glock did something with it that it's never done before. The fired case would stick in the chamber (that's what you call a pressure sign, right there) the extractor would strip off over the case head, and a fresh round would feed into the back of the fired case. Yikes that's some hot stuff, but no thanks. Two stoppages or so per magazine is more than a deal killer. If your 10 mm can cycle it properly, it would make a good deep penetrator though.
The crimp has to be a touch under the case diameter just below the crimp though, whereas I went with "about equal". A couple of these XTP handloads (2 of about 150) did fail to lock up all the way - something else that's never happened with this gun. I'm sure it's the crimp, and maybe that I need a new slide spring as this one is the original from the early 1990s and has been cycled umpteen thousand times. A gentle "forward assist" on the back of the slide was all it took. Yes; more crimp.