Howdy FJRStar, no I don't put a lock on the gun, but if I am walking away from the bike the tankbag comes with me. A trigger lock would be a great idea for folks who are just trying this for the first time and have less than 5 years handgun experience. When I get somewhere that I know I'll be for a while, asking a LEO about which range is the best has been the best practice. This accomplishes several things at once; a. It lets the officer know I have a gun. b. Cops know where the best ranges are that are the cheapest or free. c. They have excellent knowledge of great diners too.
d. Range cost has almost always been less than $20. Sometimes all they charge are the cost of targets with a donation jar on the counter. As to ammo limits, I am not sure. I AM sure that the ammo has to be away from the weapon while in transport-how that is interpreted as far as distance is an unknown to me.
Again, contact local LEO for any clarification so there's little confusion. In some cities out west guns are worn on the hip everywhere and that is openly accepted. In other cities it is frowned on and will land you a "disorderly conduct" citation on the spot.