Mark 111 blow back problem

[clayking]

I have a 6-7 week old Mark 111 that has started not staying open after the last shot. Needless to say, I then dry fire it before I know its empty. Any clues?....................ck

 

[Scorch]

Sounds like typical short cycle. I would:
a) take a critical look at the ammo (hi velocity with 40 gr bullets is best to reliably cycle the action) or
b) disassemble the firearm and clean the recoil spring.
If it is a stainless gun, check for galling in the receiver.