Some trigger time with the SIG AMT, a semi auto version of the SIG SG 510 or Sturmgewehr 57. This roller delayed blowback system was adopted by the Swiss Army in 1957 and later replace by the SIG 550.
Aimpoint Training Tip: Zeroing Red Dot Sight
Gun Gripes Episode 67: Why We Destroy Guns
Colt 1911 Complete Assembly
SHOT Show 2016: New IWI X-95 Bullpup
Lee Enfield SMLE MKIII