Well stalingrad is a bit OPed. Just had a fleet intern bb4 tournament and it clearly showed that its a tiny bit better then H39 in a 3vs3. Please notice it got 2nd smallest hitbox, only RM bb4 is smaller and with 39-40knots there isnt really a speed disadvantage.
About RM bb4: range is clearly hugely affected by its spread.... With at lvl gunners shells tend to land at Lion1 range, but when they get 98+ the range rises and becomes Iowa like but still has lots of range jumps causing to range a h44 occasionally.
RM bb5 is in 1 word underpowered. it hits less then H44. (H44 does 43-44k (inconsisty not taken into account, while RM bb5 does 41-42k but more consistently). Furthermore its spread makes it really hard to land a good salvo, at least at lvl (i have just reached lvl 106). If i remember correctly it was easyer to land a good salvo with H44 then with RM bb5. About its range its SY like but agains bad spread causes sometimes some shells to fly further.