I built a franken Glock 17 out of an SCT reciever and a pile of spare gen 3 parts, plus a factory 17 slide and glock threaded barrel. For fun, I added a compensator, which necessitated going to a lighter recoil spring to cycle cheap-o ammo.

The thing shoots awesome, except the trigger pin keeps walking out of the right side of the gun.

I replaced the SCT-whatever slide lock with a tango-down part, and installed a cerakoted trigger pin that fits more snugly.

Thing is still walkin'.

This is supposed to be fun, and my fun gun is now being a prima-donna.

None of my other Glocks do this, but then again, they are all real Glocks, not something built by a doofus.

The trigger pin is held in by the wire spring on the slide stop lever, which sits in the groove in the trigger pin.

Your SCT frame is a Gen 3 style, so will look like the diagram on the right:



So you may be installing the trigger pin too far (or not far enough), with the wire not sitting in the groove. The trigger pin should noticeably click into position when it's in place.

Or the slide stop lever could be installed improperly. Take the slide off, look at the frame for the end of the slide stop lever spring as seen below, and check that it is retained under the locking block pin as shown, which provides the necessary spring tension on the wire spring. A semi-common amateur mistake during frame reassembly is ending up with the wire spring above/in front of the locking pin rather than under it, usually from inserting the slide stop lever before installing the locking block pin rather than after.

But if neither of the above more common issues resolve it, the wire spring on the slide stop lever may be bent or damaged (unlikely since it happened with two different levers but could possibly have happened twice), or the aftermarket frame's pin hole dimensions could be off (possible but less likely than either of the improper installation errors above).

I did check the spring location, it is correct, but I think I stubbornly tried to center the trigger pin in the frame, rather than let it click into position. I just realized this now, upon stripping the slide off to check the spring. I moved the pin a bit left and it clicked audibly. I think that might be it. On my SCT frame, the trigger pin seems to sit a bit to the left, ie a bit more "flush" with the left side of the frame and visibly recessed on the right side.

I know I should have bought a real G17... haha