I just can't remember any accounts *in the lower 48* where a gun in a survival kit meant a hill of beans.
On the other hand, handling immediate acute issues have made crashes survivable: communication, medical needs, water, shelter, and finally food. I carry a PLB, a SPOT, signal mirror fire kit to theoretically address communication. A medical kit complete with percs and salts and lots of bandages, epinephrin, and burn stuff to address some of the medical issues. Some water tabs, some aluminized mylar blankets, and a couple other small jugs of water with some snacks to theoretically address the other issues.
But I place *very* little hope in the survival kit. If I live past the initial impact, the stats say I will probably be injured, and have a fair chance of being seriously injured. Serious sustained injuries has a pretty short survival fuse. The key is getting help fast.
The most important survival tool to me is an accurate flight plan with FSS, a plan with family or friends on the ground, and using flight following as much as practicable.
For IFR plans, the time to contact with S&R personnel is just over half a day. If you are VFR *with flight following*, the time is similar to IFR time. With VFR plans, it is much worse- about a day and a half (although the median, rather than the average, is closer to 24 hours).
If you don't have a flight plan, you'd better be prepared to read a book with your remaining eye if you are lucky: you'll be waiting almost 2 days on average- and that is simply a bridge too far if you have serious injuries.
Flight following is easy to use if it is available. You sometimes have to be pretty high to maintain service (see MCA's for nearby airways, and take off maybe 1k' -2k' ).
http://www.avweb.com/news/avtraining/183268-1.html