I have relined rimfire chambers but wonder if it is a good idea to reline a centerfire chamber.

Bought a ruger no.3 barrel that was 22 hornet. It has been chambered for 5.7 spitfire. Was hoping to just ream it to 218 bee but the chamber is too big. 

Thinking about lining just the chamber and reaming to the bee. The liner length should end up just short of the bees case length. 

Concerned the bee may be too much pressure. Good or bad idea?

Mr Taylor, I am afraid that I totally disagree with you. Threads & Loctite!! I know that we are living in a modern disposable age, but tradition is usually based on experience and sound engineering principles.

I have been told ( and this is the way I have done it upteen times) to bore and ream the chamber out to 1/3 more than the actual diameter of the new cartridge. Depth should be at the new cartridge length or ideally a millimetre or two shorter. Degrease and flux both the chamber and the insert. Tin both the new insert and the newly bored chamber with lead /tin solder, preferably using non acidic flux, let cool, polish with steel wool to remove excess solder. Gently heat the barrel breach and tap the insert home. If the job has been done properly, one will notice a ring of solder in the bore where the insert meets the barrel bore and some seep at the back of the barrel. That indicates that there are NO voids tween the insert and the barrel proper. Chamber, headspace and you are done. 

This process is not suitable for full auto firearms as the heat might soften or melt the solder 

Thanks everyone. 

There may be many different reasons for lining a chamber. Sometimes it's a desire to keep a highly desirable barrel functional, without visibly changing the barrel. 
I made a barrel with integral rib, sights and sling swivel base, chambered for the 375 H&H Mag. The rifle was eventually rebarreled but with the use of an extension and a liner the barrel is happily serving on a Maynard. Another example, where a short chamber liner might be appropriate, would be a barrel with engraving. Finally, there is considerable satisfaction in simply being able to do a safe chamber lining job.
mqabbi and Mr. Taylor
The few chamber lining jobs, that I've done, seem to be a combination of your methods. I like the threaded/Loctite method of Mr. Taylor but have always wanted the new cartridge to end just forward of the new liner. I wanted to avoid any possibility of pressure damage at the liner to barrel joint.
Otto