After purchasing my P12, I heard stories about problems with the recoil spring plugs failing on Officers Model Colts. I found that interesting, since the P12 is basically a high-capacity copy of the Colt OM design. This failure involves the recoil spring exiting from the front of the pistol, leaving you with a 26 ounce short club for a weapon.
I had my local gunsmith replace the recoil spring assembly with an Ed Brown Officers Model Guide Rod Sytem. Installation requires some metal removal from the underside of the slide to accomodate longer spring length/travel. This removes the cap problem and also removes any possible spring-bind problem in the original design.
This modified P12 has run well over 1500 rounds with no problems with HP, ball and handloads since. I have no proof that reliability was improved, but no failures indicates it's a pretty stable design.
Field-strip procedure involves using a drop-in pin to capture the recoil spring. Not at all difficult - just different procedure. If you're concerned about losing pins, just use small finishing or panel nails clipped off at about 3/8" from the head for a lifetime supply.
My only other mod was a 4# trigger job by the same pistolsmith.
I installed an "EFK Frame Saver Dual Action Recoil Spring for Para Ordnance P12 in .45 ACP" and it works fine. I have run a variety of rounds through it without a problem. It did not require any modification to the gun to install it. I plan to eventually change the sights.