Sellier & Bellot 180gr FMJ from Lucky Gunner through the Glock 20. I also had most of a box of 9mm and decided to run it through one of the 22rd ETS magazines I'd recently bought but hadn't used yet.
I had forty rounds of nine and loaded them into the mag twenty at a time. Although forty rounds isn't indicative of anything, I was pleased that there were no hitches whatsoever. (I put another sixty-eight rounds through it yesterday morning as well. I'll try and keep a running tally...)
The Glock 20 on the other hand...
There were three on Friday, on rounds #3, #5, and #47 of the day (#1,683, #1,685, and #1,727 of the test).
Page 84 of my Glock Armorer's Manual says the fix is either a
good cleaning...or possibly it's a too-tight extractor. (Which might explain the
intermittent and odd failures-to-feed, as well.) When I tear this thing
down for a cleaning at the end, the extractor (and extractor spring)
will be getting prophylactically replaced. I'll be keeping an eye on
this one in the future to see how that affects things. Another good
reason for keeping log books on guns...
This makes 1,730 rounds since the Glock 20 was cleaned or lubricated, with six failures to feed (#401, #454, #1,213, #1,297, #1,413, #1,593) and eleven failures to fire (#598, #1,016, #1,029, #1,376, #1,595, #1,628, #1,633, #1,640, #1,683, #1,685, #1,727). 270 rounds to go.