Made a coat hanger snap gun a while back. I tried it on some kwiksets (2 key in knob and 1 deadbolt), a couple master padlocks, a Brinks R70 Diskus style, Brinks key in knob, and 3 American Brand padlocks.
All of the kwiksets opened, although I could get them much quicker by hand, except for the rare occasion where it would open on the first snap. A master padlock opened and I can get it to open with a couple snaps most of the time. (It has an easy bitting and can be opened by rocking a straight pick in it. Not much accomplishment)
The Brinks R70 did not open, but I didn't expect it to. It seems to have some spools or mushrooms as well as a little spring tension to overcome. I did not try very hard to pop it. Just gave it some pops for 15 minute adjusting my technique. No go as of yet. I will try again sometime when I am bored. I can pick it consistently within 30 seconds with a hook. More fun to single pin this one. The Brinks key in knob lock was a different story! It had been giving me some trouble raking and single pin. It opened! Took a long time with the snap gun, like 7 or 8 minutes and wasn't much fun. (Until it opened, of course, hehe)
Hmmm... homemade snap gun on an American brand. I've seen it done, but I cannot do it with my mine.
Single pin picking I can do. These are not easy though. Not for me yet, anyway. (I do have my good days though!) Takes me anywhere from a couple minutes to an hour. (or till I take a break... never give up!) 3 models tried were series 40, 5100, and 5200 for information.
Bounced with an extremely light tension on the kwikset key in knob and can get those in around 12 snaps. Held an extremely light tension on the kwikset deadbolt and angling the tip upward and snapping from back to front in a single pin kinda style gave me best results on my particular deadbolt. With the master no. 1 padlock, just held at a slight angle and kept snapping for best results. If the angle was just right it would be a one snap wonder! Bounced the tension a little more wildly for the brinks key in knob lock. (Has some high-low bitting I found out!) So in general, bounce the tension, but occasionally just a really light consistent tension can work.
By bouncing the tension I mean both a back and forth between the snap and wrench, and also just random bounces/snaps.
In my opinion, this thing needs a little more kick! A stronger material than a coat hanger would help. Slightly thicker would help and finding just the right diameter for the spring part of it would be some avenues of improvement. I'd like to try it on a schlage and anything else I can get permission for. I would recommend that people make these and try them out. It's cheap and you learn more about your locks, believe it or not.
I learned a little more about springs by making a homemade snapgun. Here's a link for everyone that may provide something useful: http://home.earthlink.net/~bazillion/springs.html
Someday I will try to make a better one. For now, this thing is a nice little toy that could sometimes be useful. I still prefer manual picking, of course!
Just remember that how the gun is held and snapped is very important especially with homemade snap guns. You need to make sure you don't dampen the snap by holding it funny. Transfer as much snap as you can to the pins. It really is a skill. Different from standard hand picking, but the things you learn about tension with a gun can be adapted to possibly improve your manual picking! It really believe it helped my manual picking, a tiny little bit. It being a bit on the weak side forced me to get as much transfer of force as I could. (I still want more kick, though!)
GOod luck, read about springs, and make yourself a snap-gun if you haven't already! Do not neglect those manual picks though!