A tactical rifle stock is a specially made stock designed for stability and the ability to stand up to regular hard use. It is made of fiberglass, and designed to be heavier than a standard wooden stock. Wood can warp in humidity or with repeated stress, whereas fiberglass is sturdier.
The stock of a rifle is the part that the shooter holds, and it connects to the barrel and often includes a stud to attach a sling or bipod mount for the weapon. Tactical stocks can be adjusted to the stance of the shooter and are ergonomically designed to be more comfortable and protect the shoulder from recoil injury. Some stocks are collapsible, providing both a pistol-style grip and a longer grip. Stocks with dual grips are illegal in some jurisdictions because the type of stock can change how the rifle is classified.
The tactical stock is typically used on semi-automatic rifles. They are often heavier because the extra weight compensates for the weight of the barrel. Some tactical stocks have a vertical grip, rather than a traditional curved pistol grip. This is because the natural position of the hand when holding the rifle more closely matches a vertical grip.