I have read at multiple places that it is best to shoot it with the bayonet on. I have tried shooting with and without and have found that I tend to shoot high without it, so maybe it justifies what I've read? Anyway, what do you do about the bayonet with a scope on it?
The answer depends on which version of the rifle you're talking about.
First, a little background. The POI changes with and without the bayonet because it changes the barrel harmonics. The Soviets forbade soldiers from removing or folding their bayonet (depending on the model) unless they were in barracks, cleaning the rifle, or traveling in a vehicle. Therefore, the rifles were sighted in with the bayonets deployed. This was done by drifting the front sight blade for windage and filing it for elevation.
If the rifle is an M91/30 or similar model with a detachable bayonet, these rifles are equally accurate with or without the bayonet; they just hit a different POI. (It usually moves sideways, and no, I don't know why.) Adjusting the POA with a scope is simply a matter of zeroing the scope to the correct POI without the bayonet.
If the rifle is an M44 with a folding bayonet, these rifles sometimes- albeit not always
- shoot better groups with the bayonet extended. I attribute this to the fact that the bayonet flops around unpredictably when it's folded. If you want to scope an M44, I recommend removing the bayonet altogether. (You'll probably want to do this anyway to avoid getting lots of nasty scratches on your left pointer finger under recoil.
) Unfortunately, this is sometimes easier said than done; the bayonet is attached with a big screw, but Soviet armorers sometimes drove pins into the threads to keep it from shooting loose. (There was evidently no Loctite in Russia in 1944.
) As you might imagine, these pins make it really, really difficult to remove the screw; it will probably have to be drilled out.