IF you can provide the SN the chances are probably better than 1-5. I've only been had one stolen. The officer who took the report was actually surprised I had the SN. Both he and the local detectives stated that far less than 1/2 of the stolen guns they deal with have a SN provided. In that case, even if it is recovered, it makes it harder to get it back. How do you prove the gun they recovered is actually yours with no SN recorded.
Mine was recovered one month to the day after being stolen when someone in a neighboring county was arrested on other charges. Gun stolen 10-23-13, recovered 11-23-13. I was contacted by local LE and given the name of a detective in the next county. I have made contact with him, but they do not want release the gun until after they clear the case with a trial or confession. They also wanted to send it to the state crime lab for ballistic testing. I've not been in contact since early December but was told I'd eventually get it back, but it could be more than a year.
My brother had a gun stolen about 20 years ago. No word on it as of yet. I have 2 other friends who've had guns stolen. One was recovered within a week, the other after 7-8 years and in another state. Those were roughly 20 years ago too. So with me, and others I know we are 3 out of 4 at recovering them.
Actually a little better than that. I have a BIL who had a stepson get into some gambling dept. The kid "pawned" several of his stepdad's guns thinking he would win enough to get them back before they were missed. Just got farther in debt. My BIL found out, never reported them as stolen, but got them out of pawn. All turned out well. The kid has it together now, paid his stepdad back every penny, paid off all of his debts and is doing well.