The only mods Ive actually kept on my 18.5" are: Meprolight night sights, Nordic +2 extension, Nordic clamp and a cheap sling soon to be swapped out for a BFG VCAS. They come from the factory with good GRS, oversize safety, pistol grip stock with comfy rubberized grip, ambi sling mount etc. etc. Last thing Ill do is shorten the LOP and add a nice recoil pad.