So I am going to buy my first AR15, and the one accessory that I know I want is a brass catcher. this will have a full length picatinny rail, so that seems like the obvious spot to mount it. I will be transplanting a few scopes from my other rifles unless the first one (that is not mounter to a gun), a 2-7 Leopold works out perfectly. anyway, there is a plethora of brass catchers out there, and i would really not rather have several of them laying in a box because it does not work correctly, or are so complicated to use, i just cut the bottom out of it from pure frustration.