Well, you all are very nice and encouraging. Thanks so much for the comments. Really, I think there's two things that have helped me improve. One, I've been shooting a lot with a springer air rifle, which is the most frustrating device ever created to sling lead, but it really makes you concentrate on your fundamentals. Secondly, the dimensions on the 366 fit me well.
About the military marksmen, I really think that precision, offhand open sight shooting isn't really something they do much of. The best Olympic shooters in the world would probably have trouble with marksmanship tests for the military without some serious practice. From what I understand, it's a 40 round test firing from a variety of different positions at randomly appearing targets from 25 to 300 meters outside in the wind. You have to get 37 or more hits to be considered an "expert." And you're working with an issued gun, and I think it's timed. It's really its own skill set.
The NRA matches sound really fun. ISSF matches could also be cool. I have no clue how to get involved with any of that. Maybe I need to do some research.
@big al - My 336 is pretty accurate. If the barrel is warmed up, but not too hot, I can almost cloverleaf off the bench at 50 yards. If you look at the very first target in this post, you can see how tight it can shoot under perfect conditions.
http://thefiringline.com/forums/showthread.php?t=546520
One of the problems I keep running into is that my hearing protection interferes with my cheek weld. I hate plugs, so I always shoot with muffs. I wonder if there's a slightly smaller muff designed for rifle shooting.