Where I live, when shooting, outdoor temp is typically in the 70-90 degree range most of the year. Today I fired my XCR-L pistol for the first time in 40 degree weather. Set on "1" or "2", I had repeated failures to lock back the bolt on the last round fired (24.5gr WC844, 55gr fmj). Maybe it's cleaning time. Thoroughly cleaned and lubed the pistol including taking the gas system apart; pistol didn't seem very dirty; nothing seemed clogged or heavily coated with carbon/firing residue. Ran a safety pin through the smallest gas opening...not clogged. Gas block snug in place; no bolt loose. It's now 56 degrees. 55gr bullets. Using 26.5gr W748, it functioned perfectly on gas 1. Using 24.5gr WC844 (a normal plinking load for me used in a variety of AR's of various bbl lengths and what the pistol is sighted in with), it had to be set on gas 3, whereas it'd always been set on 1 to function properly before.
Grabbed four of my light frangible loads (23.5gr IMR4895, 50gr surplus frangible bullets) (should have grabbed more rounds). Before, they needed gas 3. Tried gas 3, 4, 5, 6...all failed to lock back the bolt.
Later this week it'll get into the 70's. Will need to shoot again and see if increase in outdoor temp (will get ammo up to the ambient temp too) makes a difference. Will try gas 7 with the frangibles. Oh, every mag tried properly lifted the bolt hold open when empty and the BCG was manually pulled fully to the rear, so it wasn't a mag problem. All rounds fired were stored in my reloading shed and it got in the freezing temp range last night. Glad the XCR has an adjustable gas system, and maybe it's working "as it should be" now.