The Gen 2 brace offered on the 20/21 MCK looks to be significantly longer than the original MCK/ Roni brace. But, just my luck, the first time I’ve had the Glock 20C out in a couple years it gave me multiple malfunctions. Both with the Vector Glock mags, and it’s factory mags. The Vector mags were feeding at an abnormally steep angle, and both the factory and vector mags were failing to eject. Though, it was the first time I had tried Sig 10mm, and both my 20C and 29 were having the same issues with both mags......so it might be an ammo issue. I’m going to have to do some experimenting to be sure the 20C is still reliable.
It was overhauled by the Glock factory about 3 years ago, and I haven’t really shot it since.
Lots of this happening, and brass was just dribbling out when it was ejecting. 180gr at 1250 fps advertised, and they felt hot, so they weren’t underpowered. The handful of Buffalo bore 180gr 1350 fps I tried were chucking brass to the next county and functioning fine. This thing used to like weak 10mm, and even weak .40 with the other barrel I have for it. I can’t remember it ever having a malfunction before....or my 29 for that matter.
After a bit more research, it looks like the MCK is good to go with the 20C comp ports. I guess it has an aluminum plate above the ports so it won’t cook the plastic when shooting with the stock barrel. So that’s a big plus. I’d still get a 6.5” threaded barrel for it though to sneak in another 100-150 fps and have the ability to add a muzzle device. The Gen 2 MCK has an easily removed should for longer barrels/ suppressor use, but the Gen 2 isn’t offered in the 20/21 frame yet. The original MCK Barrel should can be removed if you do surgery like mentioned above though.