AR-15 Stocks

The difference is the width of the buffer tube. Mil-spec carbine tubes have an outside diameter of 1.146 inches, with there being some slight room for variation—usually no more than a thousandth of an inch. Commercial-spec buffer tubes are larger, with an outer diameter of about 1.17 inches, and a slanted back plate instead of a flat one.

Although the difference is small, it matters, because almost all modern-production AR-15 stocks are designed for mil-spec buffer tubes. Commercial-spec buffer tubes aren't all that common anymore, so there isn't much need to check the buffer tube on a new-production rifle. That said, it's always best to check the manufacturer's manual that comes with the rifle or check the tube yourself with calipers to get an exact answer before buying a stock.

No. Stock fitment depends on your buffer tube, not the rifle itself. Carbine stocks mount on carbine-length buffer tubes and select extended buffer tubes like VLTOR's A5 buffer tube system. Fixed rifle stocks usually need a longer rifle-length buffer tube with its own buffer and spring for proper mounting, though this isn't true of every fixed rifle stock. Regardless of which one you plan to use, it's best to check which buffer tube your rifle has before you order and match the stock to it. If the stock you want needs a different tube, you can find one in our buffer tubes category.

The best AR stock is the one that offers the features you want and best matches your rifle's intended purpose. For general use, a collapsible carbine stock is light, adjustable, and fits most setups. For home defense, look for a stock that locks firmly and adjusts quickly to fit different shooters. For a compact build, a PDW stock collapses much shorter than a standard carbine stock. And for precision shooting, a fixed or adjustable stock with a cheek riser offers the most adjustability to ensure your head position is repeatable and aligns with your optic.

A PDW stock is a compact stock that collapses much shorter than a standard carbine stock. It uses its own buffer system, so it usually replaces your buffer tube rather than sliding onto it. The upside is a very short overall length, which is better for storage and use in confined spaces. The tradeoffs are a thinner cheek rest and components that do not swap with standard carbine setups. See our PDW stocks to compare options.

Yes, you can, but only through a folding stock adapter. The buffer tube on an AR-15 holds the buffer and spring the rifle needs to cycle, so the stock cannot simply fold out of the way. A folding stock adapter installs between the receiver and the buffer tube and lets the whole assembly fold to the side. Most adapters are built for storage and carry, not for firing while folded, so you'll need to unfold the stock into the fixed position to fire your rifle.

Swapping a carbine stock onto a tube you already have is easy. Most slide-on stocks go on in a few minutes with either no tools or a single tool, and the job is a common first upgrade. Stock swaps get more difficult when the new stock needs a different tube. Moving from a carbine tube to a rifle tube, or installing a PDW system, requires you to remove the old buffer tube and buffer system, which takes an armorer's wrench and some care. If you're uncomfortable with doing this on your own, a gunsmith can quickly remove and install your stock's components.

Sometimes, because their fit depends on the buffer tube, not the caliber. Many AR-10-pattern rifles use a carbine buffer tube with mil-spec dimensions, so a carbine stock that fits an AR-15 will fit those as well. Others use rifle-length or proprietary tubes that take different stocks. The buffer and spring inside the tube are a separate matter and are not the same between the two platforms. Check your buffer tube type first, then pick a stock made for it.

B5 Systems and Magpul are two of the most popular AR-15 stock brands we carry, and both make stocks that are known for durability and a solid lockup. B5 Systems stocks are widely used on duty and service rifles. Magpul stocks come in many styles and colors and are a common first upgrade on AR-15s. Which brand is "best" depends on the features you want. We recommend using the brand filter to compare every option we stock.