It appears the options for a solid slot base for the flat rear receivers are much more limited than for the round rear receiver. I may get the Warne for my flat rear (300 win mag) or just take my chances and stick with the EGW with the channel in the center that I already have and hope that it holds up to the large scope that will be on it (I think it will but just like knowing that a part is more than strong enough). On my round rear receiver (338 win mag) I have the standard EGW base but will likely switch it to either the HD or the Weaver tactical as the steel bases (Warren, Ken Ferrel etc.) are nice but I can't afford to put them on all of my rifles. I would be scope base poor! That would be a ton of money just in bases if I were to put them on every one of my rifles. I've heard others on here though say that they have the standard EGW bases on 338 Edges without any problems so maybe I'm just being too paranoid.