You make the default sight and put on it, it cost you one steel or something.

Then you take the other gun and you get the option to attach the stored mod.

This only work for the same type of weapons even the ones who looks very much the same as machine pistol and combat rifle or simper and hunting guns.

Thank you I will try it. All I remember is I took a Bayonet off a rifle and when trying to mod another gun, I couldn't do it. Maybe that can only go on rifles, so I don't have the option to put it on a hand gun for example. Would I be able to put this bayonet on any rifle or just the type of rifle I took it off? I think it was a pipe rifle.

Mods are all very weapon specific.

A pipe rifle mod wont go on a hunting rifle for example.

It has to be the same type of weapon. Pipe to Pipe, shotgun to shotgun, etc...

There are pistols with bayonets though I don't see them too often.

Assault and two barrel shotguns are also different type unless mistaken.

Sights and supressors are most annoying, why could I not replace the night vision scope on the gaus with an normal scope who let me see trough it during the day until gun nut 4 while I could use any type of scope on pipe weapons at gun nut 2 or something. Yes I know its balance but still annoying.

You are right and you are also right about the scopes. If anything, those should be interchangeable between weapons. I mean, they are the same on every weapon!

Thank you again everyone.

This in a nutshell is what to do if you find the game too hard.