There was a time when .45 factory loads were getting a little weak, some not even breaking 800 FPS, but I think the Winchester Ranger loads are not that way. If the standard pressure loads are somewhere around 850-875 FPS, I would be fine with them.

I no longer have a G21 but when I did I remember using a box or two of Ranger +Ps in it. Don't recall any trouble at all. I still have about two boxes left and I have used them a time or two in my M&P45. What little testing I have done with it, it seems to shoot them very well.

When I buy more, I doubt I will order the +Ps, but if it happens that they are all I can get, I would not be unhappy. They are pretty good .45s, from what I have seen. Unless you plan to shoot a huge amount of them, I doubt they are going to do a G21 much harm, but that is JMHO.