I have had or have 3--the Glock model 20, model 20SF and a Kimber --all in 10mm...

While I have not shot them a ton, can honestly say with the bit of ammo I have used, Horady and Buffalo Bore, have not had any feeding problems yet..got the Glock as a gift about a year ago..and as stated, have not shot it much, less than 200 rounds so far..but no malfunctions you speak of.

Dont think mine was the Gen 4 yet..have to look to verify..have to say even with my bigger hands I felt the regular model 20 was like holding a brick..MUCH prefer the Kimber..

Ripp