TomFromTheShade

The first thing I would do is clean the gun very well. Strip it down and clean and lubricate everything.

Do you handload? If you do you could be building up too much pressure. This is something that can cause a sticky action.

If you are using factory ammunition this is probably not the case, but you have to consider it.

Look at when the problem started. If it is recently, is there anything that you have done differently to cause the problem? Have you started storing the gun differently? Have you used a different cleaner on the gun? Have you switched brands of ammo? Think of whatever you can.

The next thing you should do is take a look at the action and see if there is any part where the metal is worn. This will typically be your problem area. It will be worn from metal on metal contact, and may need to be shaped up a little bit to make the gun operate reliably.

Chances are though that the wood around your bolt handle has swelled for some reason and this is causing the bolt handle to stick and require some shaking to get it to break loose to operate the bolt. I would check this out just to be sure.

I can't think of anything else, but if you can not find the culprit through these measures then I would suggest taking the rifle to a reliable gunsmith to have him give it the once over. Remember though, firing a rifle that is not functioning properly is an accident waiting to happen.