ejpaul - what I have found is that velocity in itself doesn't burn out a barrel. It is the gobs of powder it requires to get a bullet going real fast that does it. The heat and pressure of the powder charge tends to erode metal from a rifle barrel just ahead of the throat area. Worst case scenario is a small diameter bullet, that is heavy for its diameter, being driven by a very large capacity case. Fast twist .22/6MM shooting 75 gr. Hornady A-Max bullets at 3800 fps. 6MM-284 with a 8" twist shooting 107 Sierra VLD bullets Or even a .30-378 Weatherby with a 8" twist shooting 240 Sierra Matchkings. These are all serious barrel burners.

The long heavy bullets are actually worst of all because, although they aren't going as fast as the light ones, it takes them slighly longer to get moving when they leave the case (basic inertia) - and this gives the hot gasses and particles a little longer to erode the barrel just ahead of the throat.

If you study the various calibers and look at how much of an increase in powder it takes to get a bullet moving even 200 fps faster - then compare that to the reduction in barrel lifethat comes with that bit of extra speed - there is somewhat of a point of dimishing return here. My choice for a fast .25 caliber is the .25-06 Ackley Improved.