Your mileage may vary, but I've got a Stevens 200 in .223 as well and I've found it will shoot from 40gr to 50gr bullets with respectable accuracy, but it really seems to sing with the 55gr-60 gr pills. Here are some loads that I've worked out in my rifle, I found none were "hot" but I believe some are near published max, so use caution. All are around 2.25" COL.
40 gr V-max - CCI 450, win brass, 27.5gr varget - approx 1", wind was gusting
52 gr sierra MK - CCI 450, fed brass, 26.0 gr varget - 1.5", early load (conservative), I think the node is probably closer to 27.0gr
55 gr berger target - CCI 450, win brass, 27.0gr varget - 4 shots in to one slightly ragged hole
60 gr nosler partition - CCI450, rem brass, 26.5gr varget (sub 0.5")
62 gr berger - CCI450, rem brass, 26.6gr varget (approx 0.75")
65 gr sierra GK - WSR, fed brass, 26.0gr varget 1" (another sub 1" node possible at 25.6gr)
As a side note, N140 is a slower powder but in a pinch it seemed to be a fair substitute for Varget, the charges for the most accurate loads seem to be about 0.5gr lighter though.
Someone was asking earlier about the difference between BR4 and CCI400 primers, and from what I've read the benchrest primers come from earlier in the production run when tolerances may be a bit tighter, so presumably they are more uniform than those that come later. Other than that, they have the same cup, the same dose of the same priming compound, etc.