I am a vendor at the Tanner shows in Denver colorado.I know exactly what you are all talking about.Had the guy brought the ammo to my table,i would have bought it,with no problem.I am one of the very few vendors that will spend the time explaining how something works to a potential customer,even if they do not have the money to afford the item they are looking at.
My reasoning behind this:They will come back eventually ,wether they are alone,or with freinds,and they will remember i wasn't an ass.
I sell mostly military surplus and parts,I get a lot of tire kickers,but i also understand that if you want people to buy what you sell,you may have to instruct people in the use or operation of things on your tables.
I sometimes tend to kill a sale when someone is willing to buy an item they believe is for something other than what it is actually made for,by telling them they really do not want it,and why.This approach has actually my regular customer base really expand.
A lot of vendors are there strictly to turn a profit,I ,on the other hand,am there to have fun,turn a profit if possible,find some good deals,and make a few new friends.
One thing a lot of show attendees are not aware of,is the cost to vendors to attend these shows.
We pay our own way there and home,table fees are from $60.00 on up per table, and continually rising,the show promoters are supposed to be advertising well in advance of the show,so attendance will be high,yet they rarely do and they attempt to recoup their losses through table fees.
then we have to contend with shoplifters,and unattended children.
Can you imagine 10 of your neighbors children playing in your gun safe?
The best advise i can give a gunshow attendee,is : Go to the show and walk the tables a couple of times before actually buying anything,If you have something to sell,make a sign that people can read,stating what you have for sale and what you want,you will sell it before you make it all the way through the tables,either to another person just like you,or to a vendor looking for a deal.