To kill a gun “nut” at what sounds like close range you’d either have to be
- a close, trusted associate
- extremely lucky
- a pro
- or d) - all of the above
My suspicion would be that he met someone to purchase and expensive gun, maybe an antique had the money in his hand to hand the guy and got zapped for the money.
When I go to buy something like that, I do not have the money in my wallet, but instead in an envelope, counted at my leisure.
Being a high-profile "gun nut", he's NOT going to be taken down by some random person. The killer knows this guy is armed to the teeth, so he has to be very careful.
My guess? Pro. Like you said.
All it's going to take is a few more of these "random" assasinations and the "gun nuts" in this country will become quiet. Very quiet.
Watch for Wayne Lapierre to have a mysterious "accident".