What do the pros think is the best option for the USPc ?
Does Crimson Trace offer a trigger guard for the H&K?
What Goomba said. I myself have a GG&G rail adapter on my USP45 Custom Combat with a Laserlyte FSL-3 laser that I'm very happy with. It is very small with ambi power buttons, just what i was looking for. Much smaller than their last years model, and attaches to any standard rail. Here is a link
Laserlyte — RML FSL-3
I think the adapter would give you a lot more options as well. I would go that route.
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H&K, quality since 1949.