GH: trouble opening after firing, your help is requested

[Pa SxS]

I'd probably have someone take it apart and give it a good cleaning internally if you haven't already done so. Just to be sure it's not a crud issue.

Steel bases are not only a problem with vintage guns. In my case, my one 12ga DH would have problems with even new brass based shells. It seemed more to do with the rim profile of the shell plus a tight chamber and shallow rim cuts on my barrels. Some manufacturers have a 90 degree cut and others have a slightly rounded rim to the body wall of the base. I'd notice that on some shells it was difficult to close the action. Upon firing, I could just get the barrels to slightly release from the breach face. Taking a wooden ram rod and going in from the muzzle and pushing on the spent shell would let the gun open fully. I had the rims cut slightly deeper plus I did a little filing on the extractor. It was real tight going into it's cutout.