This is a series 80 Gold Cup modified with a Centaur barrel and recoil system. The slide stop is unique to the Centaur in that it has a slot on the top of the shaft for shims and a pin that puts slight pressure on the barrel lug to force the barrel up into battery. The instructions say a standard slide stop won't work with this barrel. The slide stop cannot be replaced or changed. This gun holds 1" groups at 50 yards so I won't be replacing the Centaur system. The problem, although minor, is that after I lock the slide open with a mag in the gun, I will drop the mag and then pull back on the slide to release it. The slide stop doesn't drop down far enough to clear the notch. I have to use thumb pressure on the slide stop to lower the slide stop and release the slide. Otherwise, the gun works perfectly. I hope someone tells me I just need a new plunger spring. Opinions ?
I would start by removing the spring & plunder and see if the slide stop still won't drop. If that is the case the shims are binding the slide stop pin enough so that it won't drop. You could change the shims, or lightly lap them, but this might cost you some of the accuracy you prize. Sometimes it's better to live with what you have rather then go to a less attractive alternative.
Look at it while you pull the slide back. Does the forward bevel in the slide's notch cam it down far enough? If it doesn't, the stop's engagement lug may not be tall enough. There's a corresponding bevel on the lug that acts in conjunction with the beveled notch that works as a cam. If you have a shock buffer in the gun, the slide may not be able to move far enough rearward to cam it down.
1911 Tuner-you hit upon the answer. This system has built in provisions for a buffer. I removed that and you were right. The slide cammed the stop down far enough to clear nicely. I never have seen much need for a buffer anyway.
I had one of those, kind of a gimmick design, but it shot well and was a no- gunsmithing improvement when I did not have a reliable local pistolsmith. In this case, I think I'd leave the buffer in and depend on thumbing down the slide stop. None of that stuff is replaceable, Centaur is long gone, and if a buffer would give any protection at all, I think it would be worthwhile.
There's another way, though it will require lathe work...and only if the amount of extra travel needed is slight. Chuck the guide rod up and face about a 32nd inch off the rear of the flange...with a corresponding amount off the butt-end of the rod. That may be enough to provide the added travel needed. The simplest way is to just thumb the stop down. If you go the flange modification route...be sure to check for coil binding of the spring.
I traded mine off a good while back and don't recall the details, but in general, ALL the parts were proprietary. Barrel with a bullnose no-bushing muzzle and an angled rather than contoured link lug. Slide stop with a recess for a little roller bearing and shim stack. Unitized recoil spring column with reverse plug skinny enough to fit through the slide tunnel without cutting, small diameter recoil spring to fit inside that plug, and small diameter FLGR to fit inside that spring. I don't recall the construction of the head but all that other stuff was attached to it somehow. I would not go tinkering with it. There are no replacements if it is messed up.
I'm not going to mess with it. It works fine now and groups better than almost anything else I have. At most, I will get a fresh 19 lb recoil spring from Wolff. I confirmed with Wolff they do have them. The diameter on a regular spring is about 7/16". The Centaur has a diameter of about 3/8".