I was surprised that I shot the P365 better than my Glock 42 and 43 and tied, or bettered, my Glock 26 on my first range visit with the 365. I had a hard time believing it. My Sig only has about 400 rounds through it. I had one malfunction the first range visit, shooting weak hand. The last round in the magazine only got about half way into the chamber. I pulled the round out, loaded it into an empty magazine, locked the slide back, and fed it back into the gun by tripping the slide release. The round did not chamber fully, and it tied up the gun. After managing to get the round out of the chamber, I learned that the mouth of the case had been pushed back in one spot, which probably made the round out-of-spec. (ETA: It was factory Winchester White Box.) I had more malfunctions than that out of my Glock 43 right out of the box.
The P365 easily fits into an IWB holster that I have for a Glock 43, a Safariland ALS holster for a Glock 42/43, and it also fits in an Alabama pocket holster for a Glock 42.
The primer drag marks on my October build P365 are still pretty bad with the Winchester White Box 115, Speer standard pressure 124 Gold Dots, and Buffalo Bore 147 +P hard cast Outdoorsman that I have shot through it. My 124 grain hand loads are not as bad on the primers.
As for the original question, Glock 26 versus Sig P365, I think it depends on the mission. The Glock 26 is a tank, and it could meet my criteria for one gun for all purposes. The 26 weighs about 4 ounces more than the 365 loaded and is wider than the 365, but it handles any kind of ammo without drama and can be neglected and abused and expected to work. I carry a 26 in the woods loaded with Buffalo Bore +P hard cast. I do not see the Sig P365 standing up to the abuse that a 26 could take. The sides of the 365 grip are extremely thin to the point where I think I could crack one side just by thumb and index finger pressure if there is no magazine in the gun. I question whether a couple of nights in extreme sub-zero temperatures (a possibility where I hang) could render the 365 plastic brittle. I also think that the long Sig rails, like the rails on traditional Sigs, call for more liberal lubrication than Glocks. But, for carrying in all but the worst conditions, with a properly lubricated gun, I think that a properly vetted P365 is easier to carry and may not take as much practice to stay in condition as the 26.
Last edited by Cheyenne; 11/25/18. Reason: add stuff
