Or if you use the same bags for travel and range use. Clean them out thoroughly. I would think it's common sense, check EVERYTHING before you go to the airport.
I still think it's foolish to use the same bags. It just makes no sense to do so. Bags are easy to have a round (spent casing or loaded) get into some nook or crevice- very easy to overlook. Humans are fallible, and I'd be highly surprised if someone could check the bag perfectly every time.
Look at it this way- how much would it cost to have to straighten this kind of thing out? At best you're looking at a fair amount of time before they say "OK, honest mistake," and send you on your way. You could miss your flight- that would potentially cost you a few hundred bucks for another ticket. If it's anything more than that- anything from a citation with a fine to something requiring actual court appearances and lawyer fees, that cost starts running rather higher- the sky's the limit there.
It isn't hard at all to get a set of cheap but serviceable luggage from Samsonite or American Tourister for under $200. A good set designed for frequent travelers can run closer to $1000 depending on the bags you buy.
The hassle and trouble from erring even once will pay for the cheap stuff. It could easily pay for the good stuff, and if a lawyer is involved, you could probably pick up a set of really nice luggage for a fraction of what you'll end up paying out.
All to save what? I doubt people are traveling with range bags that cost $100+. It doesn't make much sense to buy a pricey range bag and cheap out on the travel kit. So maybe you're saving fifty bucks?
Weigh the risk vs. the reward. It just doesn't wash. That few bucks you save repurposing that bag can cost you a couple orders of magnitude more money, all so one can travel with a bag that's poorly designed for the purpose. It makes no sense to me at all.