I have had a 4516 and one of my main carry guns is a 1066 (same frame and weight as the 4566 but in 10mm). Both guns are heavy, but once you get used to the extra weight it isn't a problem. All of that being said, if your main intent is for CCW, get the 4516/4513/457. They are more comfortable to carry. The difference doesn't seem big, but the dove tail of a 1066, or 4566 in your case, digging into your side takes time to get used to. The 4516 is just short enough that it doesn't do that.

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J.D. Roy