Quoting myself:
" I like the OACP and it can be reliable. Sorry to say though, that as it happens I have not customized one in quite a while. I have done several Defenders in the last four years but not one OACP."
"Can be reliable" are the key words here. Not necessarily "always is as at least as reliable as everything else".
Long story short, they will be more sensitive to ammo than a full-sized 1911-- as in, really hot stuff may have the slide cycling so fast that the mag spring can't get a round up in time for feeding.
And-- as hinted in the above-- mag springs have to be up to snuff. I used to think that there could be mag springs that were too stiff and cause too much drag on the slide. I now think that stiffer is pretty much always better. My OACP setup is a Metalform magazine with a Tripp spring and follower kit in it. Just about any magazine body will do (Colts are or have been made by Metalform), but the one with the floor plate held in place by mag body material formed over it is very strong. Absent that format, I like to TIG weld the floorplates as a little extra insurance against having good strong springs, since standard spot-welded floorplates do come off on occasion.
The other area that has traditionally required upkeep on the OACP is the recoil spring. What I am using currently is a flat wire spring from EGW. It's been a while since I checked, not sure they are offering something specifically for the OACP, they sure should as it simply gives you more spring for the same available fore-aft space. The spring wire is flat and wide, so the "more spring per length" comes from the fact that the guide rod has to be 1/4" instead of 5/16"..... which means special guide rod and plug. I made mine but I'm thinking they might have one by now..... and if they don't tell them they should and if I know EGW, they will!
Short version, good / fresh spings and reasonable ammo help the OACP reliability-wise.