toruk do you suggest, sonce I do most somplier mods, that I use lithium batteries in an external tray?
Well, personally, for most people I recommend NiMH rather than lithium-anything.
Edit: If you mean to refer to 14500 cells in a AA box and you do not already own the cells, I would not go down that road. Those are grossly overloaded in an application like this, give suboptimal results and are not worth saving a few bucks up front. TBH I'm not sure why that is seen so much in nerf. Not exactly safe, either. Just bite the bullet, get some NiMH or lipo packs and go.