I used a friend's match reamer (short freebore) for a 6.5 Creedmoor. Shooting 142gr SMK's loaded to book COAL of 2.810, I'm well into the lands. Rifle sizes the rounds down to 2.785 if I chamber and extract a loaded round. Using Staball 6.5, I'm getting OK accuracy, but SD's and ES seem a little high, which might hurt at over 600 yds.

Should I shorten COAL and try .020 off the lands to see if off the lands is more consistent? This'll be .045 under book COAL?

Should I be concerned that the rifle is sizing the round? I don't want more neck tension (.289 bushing for about .002 compression), do I?

I see discussions of people seating .020 into the lands, but once it hits the rifling, the bullet's going to push back into the case, isn't it?

Or just continue to add .1 gr until SD comes down?

Appreciate any thoughts.

You have turned a creedmoor into a 260 Remington with that short throat. The creedmoor was designed for those long high bc bullets to fit in the throat.
Beyond that I would just say I don’t like seating bullets into the lands by closing the bolt. Some folks do.

Thanks, Fury. Yes, I'm afraid you're right. Should have just bought a reamer.

Anybody else have any thoughts? Particularly on what happens when you seat .020 into the lands; doesn't it just forced the bullet back into the case? Or can you have enough neck tension that it'll turn and start to engrave the bullet (hard for me to believe, but could be)?

Whoever designed that "Match" reamer, was misguided in the effort; the CM needs that longer throat to function as designed. He strangled it at birth. Yours at least.
And you can't make it work without compromising it's potential; you need a proper chamber.
Oh, jamming your bullet into the lands? Sure, you can do it; it will engrave some and then push the bullet back. In any case, you can't possibly use normal loads doing that. Get your chamber fixed.
Bring it over.

What DPCD said. And buy yourself some Berger bullets. You will thank me later. A Creedmoor with a short throat "match" chamber is an oxymoron.