Take a shot and the breach opens ?
 

Hi
This just started happening today.
I should give a little history on this gun. I bought a DH action and a set of VH barrels 12 guage, put them together smoked them and have a nice tight on face gun. While I was at it I replaced the wear block on the barrels.
I shoot skeet with this and have shot over 1,000 rounds through it and it worked perfectly.
Today every shot the breach opened. I took out the bolt and it looks fine no damage. I lightly filed the wear block and made sure the bolt was making full contact. Haven't retried it yet but I don't think I improved anything, I really didn't see anything wrong.
Any thoughts ? I'm sure I'm not the first person this has had happen.

Thank you, Tom

something is not letting the locking lug be seated its full lentgh thus letting the gun come open..the fix mite be as easy as cleaning and oiling the lug...charlie

How does the top lever spring feel?

Thanks for the replys
I have removed and cleaned and inspected the locking lug ( I called it the bolt but I probably used the wrong term ).
The top spring is strong, I'm pretty sure that is not the problem.

I used a little inletting black on the wear block and found the bolt engaged about half way up the little ramp when closed. I filed the block down slightly to give it a little more engagement will try it out tomorrow.
Thanks, Tom