6.5x25WSSM I believe will give you the best barrel life while retaining the magnum bolt face. Properly built there are many reports of them being very accurate. In a target rifle not being able to feed from a magazine shouldn't be a problem.
+1 for the 6.5 WSSM. If shooting fast is a concern (which is will be if you compete), check and make sure that your gun will eject the empties. I have a BAT mod M 8.5" that will not eject the empties. Very accurate. Mild recoil. Shoots GREAT....140 Bergers at about 2930 with a 30" 1-8 twist Spencer BBL........right up there with the 6.5-284..will shoot a little faster, but this was the accuracy node. H4831/fed 210's or Wolf primers. I have not competed with it yet....it has always been windy at the matches I have been to.....I want to shoot as quick a possable and with my BAT I must pick the empties out of the gun with my fingers.......but the first nice mach day I will throw on the 6.5 tube. It is going to take up coyote population control duties this winter!!!
+2 on the 6.5 wssm. I've got 2 one on a push feed action and one on a controlled feed action, both Savages. The controlled feed ejects just fine the push feed will not eject at all, just drops the empty on the follower. That little case is just a tad to short for the extractor claw to hang on to long enough to clear the ejection port, misses by less than 1/4 inch.
Both are plenty accurate and brass life hasn't been a problem at all. Can't help with barrel life yet, just not enough rounds fired yet.
Ignorance can be treated with education, sadly there is no cure for stupidity.