In short, yes and no! The SUIT is 'calibrated' for up to 300yds in the high position and up to 500yds in the low position (yes, the graticle is a foresight in optical terms.....) so if you zeroed it in at 300 yards or in accordance with the user handbook (in the case of the L1A1 rifle) then regardless of the twist or ammunition, then it should be 'on' at 500 yards.
I say 'on' at 500 yards in much the same way as I say 'calibrated' at 300 yards. The SUIT was never a telescopic sight but is what you might forgivingly call a 'sort of good compromise if you were in a kind mood' sort of sight.
So in short, zero yours in at 300 yards and see how it shoots at 500 and it won't be far out ....., sort of......
It was one of these things that the BritishArmy got by default really. It wasn't quite what was needed but it filled a hole. Mind you, with the prices sky rocketing, I wish I'd kept a few!
BDLin SC has user handbooks