that's right, the title is my problem with my newly customized 1911: its slide does not lock open after the last round is fired.

a friend (not a smith) told me that the problem is due to the "slide stop", explaining that the slide stop for a 45 type is different from that of a 9mm or 38 Super.

is this true? all along, i thought that slide stops are of the same specs in all 1911 calibers.

Yes, it is true. The mags are different between the calibers. I believe that the .38 super mag is thinner and requires a different slide stop. The slide stop is activated by the mag follower pushing the slide stop to the upper position when there are no rounds left in the mag.

Now it's clear to me why I'm having such problem! Thanks a lot, stumbler! I really appreciate your input!

Stumbler nailed it right on the hittin' place. The slide stops are different
between the two calibers. The one for the .38 Super/9mm has a longer lug,
and the shape is slightly different.

Cheerios!

Tuner

The slide stop could be the problem, but if the recoil spring is too strong the slide stop will never get a chance to work. Try a lighter recoil spring, its a lot cheaper than a slide stop.