Just for clarification... the M14 evolved from the M1 rifle. The M14 can be made to be either select fire (semi/full-auto) or semi-auto only. The Springfield M1A is based on the M14 design, but an M1A receiver can not accept an M14 trigger group. M14 rifles shoot the 7.62 x 51mm cartridge (very similar to .308 Win) and the M1A is generally chambered in .308 Win. The M1 Garand, as adopted by the DOD, was chambered in .30-06 and later some were chambered for the 7.62 x 51mm.
The M16/M4 rifles look absolutely nothing like a Garand/M14/M1A pattern rifle. Incidentally, the Ruger Mini-14 is essentially a scaled-down M1A. It's chambered for .223 Rem just like most AR-15 rifles.
I happened to see a parked F&G Warden's truck and it certainly appeared like it had an M14 with a compensator (not a flash hider) in the rack. I couldn't see the left side of the stock below the rear sight, so I can't say for certain that it was an M14, but presence of a happy switch would be pretty concrete evidence... The stock did look fairly old... like my Garand's stock. The compensator (aka brake) looked like it'd been in place for a while. After doing some research, it may have been an original M14 compensator.