Well, for starters it depends on what bullet you plan on running. Most of the common powders - N140, N150, H4895, Varget, etc. will work across the entire range of bullet weights below.
From there...
155s in general run really well pretty much anywhere from 2900 fps on up. 2950-3050 seems to be the traditional sweet spot.
185 Juggernaut... 2700+ works well for a lot of people; the US FTR team loads in 2013 were in the 2750-2775 range. Some people push them to 2800+, and there are some accurate nodes up there, but I'm not sure the brass life is going to be all that great, even with SRP cases.
200 H / 200.20X... there are a number of 'sweet spots' that work. Seems to depend on what your barrel likes. 2620-2640 is one, 2650-2670 is another... and in theory there is an OCW node just past 2700 but getting there without wrecking brass is tough. In my opinion you're probably better off going with the lower node at around 2620-2630-ish, and have your brass last longer and give yourself a little bit of a buffer as the weather warms up.
Most of the above is predicated on a nominal 30" barrel, with a 0.170" freebore for the 185s and 200s, jumping somewhere around 10-20 thou. Longer barrels pick up a little bit of speed, and shorter ones give up some - but may be easier to tune. If you pare about 15-20 fps off that 2630 fps lower node for the 200.20X, that's right about where several of my barrels liked to run at.
Then again, you always have the exception to the rule... had a *factory* 12 FTR barrel a couple years back, shortened to 28" and re-crowned, throat extended to 0.170" with the same reamer as all of my custom tubes... and that stupid thing shot great around 2670 fps, with zero pressure signs
Long story short... don't get greedy for speed. As James Crofts has said... "speed kills" (your groups with the 200s)
