Softair and pellet rifles are the ultimate low cost trainers. Softair versions of your firearms can be used almost anywhere you can hang a blanket. Semi auto pistols that blowback and full auto carbines etc are available in most popular platforms. You can use them in your carry holsters etc. You can run drills just like you can with firearms. Pellet rifles and pistols can also be used to run drills etc. Like I said in my previous post a decent pellet rifle is the best long range practice. A pellet rifle at 100yds is like a 300 or 50bmg at 1,000+ yds.