A buddy and myself shot our M4’s today and I also shot his S&W .45. The trigger on his .45 is machined with vertical grooves on it for anti-slip I would guess.
I see a lot of pistols with some type of machining on them for improved grip. Here is a pic in case anyone is not sure what I am talking about.

Does anyone sell a replacement trigger with any type of machined surface like a pistols?