500grains - spot-on. I do like that sight picture. Now, if the stock is appropriately shaped for them, there's really no need for more than a really low mounted 2X to 4X scope, if at all.
: I've done excellent work to 300 meters with express sights & see them as the ultimate hunting sight. They are excellent for accurate paper shooting as well. The firnt bead just sits in the bottom of the "V" and no problems with, 'is it centred' - it's always centred - "bang/flop - oh what a relief it is".