Thanks for the additional details. schak, I know you will probably think there is no way, but it is very unusual for a spouse to start behaving this way without there being an OW. Could this group of "gun club" friends involve a woman?
I am not trying to alarm you but the fact that you are not welcome is a huge red flag. I just went to my gun range (I am a member) last night. If my wife ever said "hey, its been a while since I went shooting, can I go to the range with you?", I would be all for it! So there is has to be a reason for his not wanting you there.
Also, the one night and two nights away, especially the one after returning after the gun club is another red flag that maybe there is an OW involved with the club. And don't be fooled by him asking you to leave. Wayward spouses are capable of all kinds of ruses. Most likely he knew there was no way you'd leave but he knew asking you to leave would throw you off the trail of what his "nights away" were really about.
I hope I am wrong about this, but my A radar went off with your most recent post.
M(53), W(54),D(19) M-23, T-25 Bomb Drop - Dec.23, 2017 Ring and Piecing since March 2018