You also have to take into account what the person may or may not do with your weapon. What if they commited a crime and returned the weapon to you? You would unknowingly be in possesion of a weapon used in a crime. And it would be really hard to explain to the DA that you conviently "loaned it to a friend" on said night. Run balistics and bam: you are charged with a crime you didn't commit (because he/she surely won't admit to it).
Again its your right to do with your firearms as you please but you should definitely weigh the pros and cons before you do. At best case you get your gun back in (nearly) the same condition you loaned it out in. How about going to the range with your friend so not only are you bonding but you can give direct feedback and more importantly WATCH YOUR FIREARM.
Two quick stories: I recently loaned my sister my. 22 target pistol to take her handgun class. It's my sister, I'd do anything for her. Also my fiancee took the class with her. If she damaged it I know she would gladly replace or pay for anything she did, even though I woudn't even take her money.
Last fall a close friend of mine asked me to loan his brother my Kalashnikov to "complete his taliban outfit" to a supposed costume party I didn't even know about. The guy was of a shady composition anyways... why on Earth would I want to put MY AK into his hands, much less without directly being present... whole deal seemed super shady and again there was no marginal benefit for me to do so and a HUGE oppurtunity cost... I had no qualms telling him a big negatory no-siree.