I am thinking there must be a size that works well for most....I have a 3.6 and I am finding it difficult to maintain the sight picture. Could it be my holding and that I need to practice more or should I buy a smaller insert ?
would have thought something like 4 - 4.2 would be a more optimal place to start... 3.6 is pretty tight, and may make a hold seem more loose than it actually is, as well as perhaps causing issues of the eye not being able to see enough white around the target.
I agree with Rob. Particularly true if you're not yet in, say, EricU's class as a shooter. I use a 300 and and FWB C-62; the C-62 is longer, and I'm at 4.2 and wanting a larger opening.