This may sound crazy, Grant, but my 1929 SC opens after every round when shooting Winchester 1145fps #8 shells BUT NEVER opens using Remington 1145 or 1100 #8 shells and never opened using RST shells when they were available. I have no idea why and shoot the Remington shells exclusively. I do not "snap" the gun shut - I release the lever before closing it tight. Good luck - these are great guns!

Do you put grease on the wear plate?

Sorry for the late reply.......no, I don't grease any internal parts but clean the gun regularly...sorry again!

My understanding from Chris Dawe at Stillwater Restorations is that this is a pressure issue. Higher pressure ammo. I get the same thing shooting 1 1/8oz/1255fps Winchester Super X field loads through my Ithaca NID4E yet I can put Eley Bismuth loads of 1 1/4oz 1250 fps loads through without issue. Chris advised me to not to continue shooting loads with higher pressures and to search for or reload low pressure loads or risk eventually putting the gun off face. I heeded his advice after 5 rounds and have been running low presdure 1oz loads ever since w/o a hitch.

I’ve had this same problem with an Ithaca Flues SBT, an Iver Johnson Specialty Trap and a Fox SBT. In all three cases the issue was with the locking bolt.