To cheaply sell a rifle:
1. Make a small sign with the gun price that's easy to read from 20' away
2. Tape the sign to the end of a chopstick
3. Put a sling on your rifle
4. When at the show, put the chopstick sign into the muzzle and sling the rifle over your shoulder
5. Walk around
Be sure to zip tie the rifle action.
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1-I've seen people do this before. But if you think about it, unless you are a vendor/table holder, it would be a violation of the "place to keep" clause.
The gun show, per se, is not a place of business, gunsmith, shooting range or police station.
2-Show rules prohibit wearing of firearms at the show unless you are an HHAA re-enactor or security staff.
My recommendation is to display a photo or perhaps print out a page of photos and descriptions and pass them out to people who might be interested.
Include your contact information on your flyer. That would probably be a more effective method of advertising anyway.
The other possibility is to secure a table reservation. There may still be tables available, even though the deadline for reservations has long since passed.
It would be up to the show coordinator to allow a late reservation. However, holding a table comes with a whole different set of rules that you must agree to.
If you want to attempt a late reservation, you can try contacting the club. The number is on the flyer.