I haven't had it happen but I'm not surprised. There are many variations of Ruger 10/22 so take this advice with a grain of salt... but if it's a metal sight in a metal base without a set screw:
1. If it's just loose you can maybe stipple the bottom of the sight. Take a center punch and make some dimples on the bottom of the front sight to rough it up. Trick here is you need to support the sight without bashing in the top blade--be careful. I've had good luck making supports out of scrap wood for tinkering with my 10/22. I wouldn't stipple the base or modify that at all.
2. if it's really loose, maybe you can shim it. Take a coke can (or any aluminum can) and cut a little piece out. Hammer it flatter if it's too tight. You can smash them really thin.
3. call ruger and ask them to send you a new front sight--good to have anyway
check out rimfirecentral.com forums for anything and everything 10/22
fyi, I was at four seasons this week and they sold like all 5 of their "just got them in" 10/22 in less than a week. maybe you were the guy buying the last one, the display model?
