And let us not forget that enfield rifling was designed for flat based bullets.

To shoot accuratly the bullet needs to form a good seal (or obturate) to prevent gas blowby. With a boat tail bullet this might not happen. Remember that a lot of barrels are nearly a century old are often not up to the highest standards. They need a bullet that will obturate in order to fill the barrel completely, preventing gas blowby which will destabilise the bullet upon exit from the bore. Flat based bullets do this best.

That is not the say that they will not work. If you have a bore in good condition it may shoot them really well. But if your bore is slightly oversized (like most of my enfields), or worn, they may not.