Shellshock - sorry about not replying sooner, on the road at a project.
Problem with a factory rifle is that the chamber is usually on the generous side. While there isn't anything wrong with a little extra freebore, I've found the generous factory chambers allow over expansion of the entire case. Full length sizing after every firing overworks the brass. This is somewhat alleviated by neck sizing but at some point the shoulder will have to be bumped a bit, and maybe the case full length sized depending on what sort of a die collection you have. Size your brass as indicated by how it chambers so don't go and load five times fired brass 100 at once just to find it's a really tight fit to the chamber. Pulling loads back down sucks. You'll have to learn the specifics for your rifle through experience.
As far as all the powders and bullets go, there aren't but three powders for a 6.5 X 284 as far as I'm concerned, H4350, H4831 and RL-22,winchester primer). As far as bullets go I settled on the Lapua 139s. The other common choice is the Sierra 142. I got my combination to shoot well and now the only thing I've done is adjust for a different lot number of powder. There isn't really any sense in trying to get past the node that should occur around 2950 fps.
The trick is what to do for your next barrel as the 6.5 is pretty hard on barrels when shooting strings in competition, and still hard on them in just recreational shooting. Doesn't really matter much which barrel you get although Kriegers and Bartleins seem to get the nod most often, just get one from a reputable maker. Of more importance is a good smith as often a barrel is blamed when in fact the smith screwed up a decent barrel by not chambering is straight or on the centerline of the bore.
But regarding the resizing issue. When you rebarrel, get a match reamer from Dave Kiff. Measure representative samples of the brass you are using with bullets seated, order the neck size .003" over that diameter,just remember to check new brass to unsure the neck thickness is the same as the batch you measured). A Redding full length die with a Redding +.002" competition shellholder,sets back the shoulder .002" LESS than a standard shellholder) pretty much perfectly fits the chamber. Sometimes as the brass work hardens you'll have to go back to the standard shellholder to get the right shoulder set back. Work hardening can be fixed by annealing. A $15 hot plate turned on high, a thick piece of steel with countersunk holes of slightly larger than neck diameter, a little Tempil Fluid to see how long it takes to anneal the first case against a clock, then load up the plate and pull the cases when that time has elapsed. Cheap way to anneal cases.
Anyhow, the nice thing about having your own reamer is that all your subsequent barrels should have nearly identical chambers. Spend a little more and get a floating pilot reamer, your smith will thank you. Mine was surprised when I showed up with a new reamer and complete pilot set.
Yeah, the initial cost to the 6.5 party can be high, but once you are there it's just fine tuning. I haven't really changed anything in about three years,I own my own reamer,s) and my smith cuts really good chambers). You'll know when you've got it dialed in too. You'll be a happy camper.
