Thanks for the PSA. This is a life or death reminder when you are dealing with your EDC. Some folks forget to rotate out old ammo as well. Prolly will never be a problem but I don't like "probably" when it comes to that SHTF moment.
Knowing that Jeff has far more experience than I do, I have to defer to his preference to M1 5w20. That said, I tend to want everything to be stock. Especially stock replacement. I find that when you stay with Glock factory parts, the more reliable the gun is.
I guess my way to resolve my hesitation to M1 is I'll just have to shoot all guns on a regular basis.
"Honest dear, the experts say I need to go to the range more often" 
Now I just have to make sure there is enough food for all my children when I get to the range.
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Joe
See Porsche run. Run, Porsche, Run:
`87 911 Carrera