Solitar:
You are talking about shooting into LESS than 1 minute of angle.
The 10 ring on the 600 yard decimal target is 12" diameter(2 minutes).
With all one hears these days about "sniper rifles" and so forth and so on, a 2 minute rifle might not seem all that great, but consider this. ANY rifle/ammunition combo that will hold the good side of 2 minutes or even 2 minutes can, in theory, shoot a POSSIBLE SCORE AT 600 YARDS. Lots of rifle/ammunition combos will shoot tiny groups at 100 yards, off the bench or over a rest. Shooting at the range you mentioned, 500 yards is another thing entirely. For instance, while the rifle/ammuniution might be capable of such grouping, how about the shooter.
Back when I could hold a sight picture at 600 yards with iron sights, I used to shoot at least 190 x 200, with Model 70's, both 30-06 and 308, using bullets ranging from 168 to 190 grain. On a "good day", I could hold 10 ring elevation, lost points going to windage errors. Did close to that with an M-1 also and I never got beyond the Expert class (civilian).
Out to 600 yards a good 308, with appropriate ammunition would lilely outshoot, by a little, the equivalent 30-06. Beyond 600 yards, the 30-06 is what I would prefer. To each their own.
Am not familiar with the Remington's mentioned, and no longer shoot rifle anyhow, however for "across the course" use, the Model 70 just seemed to work better than most bolt guns, and I had a 40X too.
[This message has been edited by alan (edited May 30, 2000).]