Exactly 36.5" from the rear of the butt plate to the tip of the gas plug locating/alignment prong at the end of the gas cylinder. BUT, be warned that if you are thinking of carting your gun about without the barrel, the gas plug locator on the gas cylinder is VERY vulnerable and sticking out like a bulldogs balls, is easily damaged. You CAN straighten it out if it bends - BUT ONLY ONCE! You can also replace a gas cylinder but................

Best advice is to cart it about assembled