Most reliable has been all of my S&W 745’s (45ACP) and they have been my most used handguns of all I’ve ever owned. Ammo is virtually all my own handloads using a Speer 200 lead SWC with 4.2 of 700X. Usual range round count session is 200 rounds. Total 45ACP round count probably 20K+ from all pistols chambered for this round. Roughly keep track by the primers used on my loads. I still have over a case (5K) of Federal large pistol primers.
Prior to increasing the number count (quantity) of the 745’s I’ve owned a Sig 220 (early heel mag release) and a number of CGC (Colt Gold Cup) series 70 (no firing pin block/safety). All 45ACP. The 220 was the next most reliable needing to be well lubed at the rail, the Sig has a lot of rail. The 220 was the most accurate of the three even though it didn’t fit me well. A change in only powder charge volume would be a change in the vertical impact of the target only. The 745 and CGC would change additionally horizontally with the same change in powder charge volume used in the 220.
The CGC, a 1911, has been a real learning experience for me. While I don’t recall ever having issues using factory new Federal JSWC ammo, round count usage of this ammo was very limited because of cost. My handloads would give an occasional stovepipe or some other ejection issue. While many would call it a tune-up, IMO, modification would be more appropriate for what changes I’ve made on my CGC. Changes were made to the extractor, ramp of barrel and ramp on frame. The internal extractor was modified to mimic the function of an external extractor, works in either controlled feed or snap-over the rim feed modes. IMO the bullet/cartridge should never see/touch the lower ramp area of the barrel, this part of the ramp can be removed/eliminated. Ramp on frame is extended forward (front of pistol) to ease the transition of the cartridge into the chamber. Cartridge case head support of chamber of barrel and the slide are untouched/no changes. Occasional failures to return to battery happens because the CGC chamber is comparatively snug toward the case mouth of the chamber. The 745 is very forgiving about headspace issues.
Powder charge was changed from 4.0 to 4.2. While 4.0 worked fine in the CGC the 745 would not reliably cycle. IMO the CGC is setup for SWC while the 745 is setup for hardball.
I have/had more pistols in 9mm than all the 45autos I’ve ever owned combined. Yet my round count for the 9mm is very low, probably only in the low thousands total.
Can’t recall ever having any issues with the Ruger P89, Walther P5, Glock 19C or Beretta 84 (380ACP) when using factory OEM magazines. Aftermarket magazine with 19C would fail to lock the slide open after the last round causing an empty chamber and cocked striker condition.
Intertec AB-10 (similar to Tec 9) has a very short barrel of about 2” with no barrel shroud. Will not cycle with light ammo such as WWB.
Most reliable 22LR is the Beretta 71 with 6” barrel. Least reliable are my High Standard Victors, 5.5”.