Did you catch my post at the bottom of page 11? I'd like your feedback on my data.
I haven't made it to the range yet, but I did more testing. Did some further hand cycling, with various amounts of ammo in the mag. With a full mag, I got the least bullet setback, from 0.00 to 0.001". Half-mag produced 0.001 to 0.002". No jams. Re-cycling the same round to see if the setback continued, which it does. Tried 3 brands, 4 bullet weights, plus a commercial reload. Some move easier than others. This is very limited testing, using one Glock, a G27.
I suspect that LEO's might have more KB's, if my theory is accurate. They typically load and unload their guns each shift. Also, some have specified practice ammo, and don't normally shoot their duty ammo. If the same round gets chambered often enough, might be a problem.
What I don't know is what pressure correlates with bullet setback in the .40sw. I imagine there are a number of variables involved here, but I don't have the background to say at what increment setback becomes critical. I seem to recall hearing that along with increased pressure, it induces a spike in the presure rise, which compounds the problem.
BTW, I have seen a G27 after a KB. I arrived at an indoor range shortly after, and had a look at the remains. This was the first G27 the store received, I think, and they added it to the rentals. The rangemaster took it out first, and it grenadeded(sp) with the second mag. (They only allow factory ammo in their rentals.) I think the slide may have been the only salvageable part. Beat the hell out of his hand. They sent it into Glock, which sent back a new gun. The chamber was blown apart. Destroyed the frame, mag, trigger group was blown out. Glad I wasn't holding it. At the time, we assumed it was a bad barrel. Maybe, maybe not!