Short answer: choose a collapsible stock if you want to adjust length of pull for different shooters, clothing or body armor. Choose a fixed stock if you want no moving parts and a set fit. The catch is the tube: a fixed A2 or rifle-length stock needs a longer rifle buffer tube, rifle buffer and rifle spring, while a fixed carbine stock such as the Magpul MOE Fixed uses the same carbine tube and buffer as a collapsible stock. Our buffer weights guide explains why the two systems do not mix.
Fixed vs collapsible AR-15 stocks: length of pull
| Stock type | Example | Length of pull | Weight | Tube and buffer system |
|---|---|---|---|---|
| Collapsible carbine | Magpul MOE | 10.3 to 13.6 in (adjustable) | 8.4 oz | Carbine tube, carbine buffer |
| Fixed carbine | Magpul MOE Fixed Carbine | About 12.0 to 12.2 in | 9.5 oz; about 13.3 oz with the receiver extension | Mil-spec carbine tube, carbine buffer |
| Fixed, shim-adjustable | Strike Industries Modular Fixed | 12 to 14.25 in with three 0.75 in shims | 12.8 oz | Mil-spec carbine tube, carbine buffer |
| Fixed rifle-length (A2 style) | Magpul MOE Rifle | About 13.4 in | 14.0 oz; about 17.6 oz with the receiver extension | Rifle-length tube, rifle buffer and spring |
Figures are from Magpul's MOE Fixed Carbine and MOE Rifle pages and Strike Industries, read October 2026. Magpul lists about 12.0 inches for the Fixed Carbine in its specifications and 12.2 in its description. The collapsible MOE figures come from our best AR-15 stocks guide.
What changes with a fixed stock
- Length of pull is set. A fixed stock does not adjust, so it fits one shooter and one set of clothing. Strike's Modular Fixed gets around that with included shims, from 12 to 14.25 inches.
- No moving parts. A fixed stock has no latch to loosen or lever to catch.
- The tube may change. A rifle-length A2 stock sits on a longer tube. Magpul says its MOE Rifle stock mounts to a rifle-length receiver extension, and that on a carbine with a collapsible stock you also need a rifle buffer and spring. Carbine and rifle buffers are not interchangeable.
- It can weigh more. The MOE Rifle stock is 14.0 oz, against 9.5 oz for the MOE Fixed Carbine, and the longer extension adds more.
- Some laws name stock type. California and New York name folding and telescoping stocks in their rifle definitions; see our featureless AR-15 guide.
Our picks
Best fixed carbine stock: Magpul MOE Fixed Carbine
It uses your existing mil-spec carbine tube and buffer, weighs 9.5 oz, and Magpul says it fits without removing the castle nut. It has integrated sling loops and takes optional QD mounts.
Best A2-style stock: Magpul MOE Rifle
Magpul calls it a replacement for A1 or A2 fixed stocks, with upgrades in storage, profile and sling mounting. It is about 13.4 inches in length of pull and needs a rifle-length extension.
Best adjustable fixed stock: Strike Industries Modular Fixed
A fixed stock with three 0.75 inch shims that set the length of pull between 12 and 14.25 inches. It needs a mil-spec carbine extension and castle nut.
Also consider: B5 Systems Bravo (fixed)
B5 makes its Bravo as a fixed stock for mil-spec carbine extensions, with steel QD mounts. B5's own page lists two different weights, so we do not quote one.
Fixed stocks, with today's prices
Lowest price across the stores we track:
Magpul MOE Fixed carbine stock (mil-spec)
Pros
- 9.5 oz, about 12 in length of pull
- Uses your carbine tube and buffer
Cons
- No adjustment
Best fixed carbine
Magpul MOE Rifle stock (A2 style)
Pros
- Replaces an A1 or A2 fixed stock
- About 13.4 in length of pull
Cons
- Needs a rifle-length tube, rifle buffer and spring
A2 style
Strike Industries Modular Fixed stock
Pros
- Shims set length of pull, 12 to 14.25 in
- Carbine tube
Cons
- 12.8 oz
Adjustable fixed
B5 Systems Bravo fixed stock (mil-spec)
Pros
- Fits mil-spec carbine extensions
- Steel QD mounts
Cons
- B5 lists conflicting weights
Alternative
How to choose between a fixed and collapsible stock
- Check your tube first. A carbine tube takes carbine stocks, collapsible or fixed. A rifle tube takes an A2-style stock. Our mil-spec vs commercial guide explains tube diameters.
- Do several people shoot it? A collapsible stock adjusts; a fixed one does not.
- Want to keep it simple? A fixed carbine stock keeps your carbine buffer and tube, with no moving parts.
- Building an AR-10? It uses .308 buffer parts. Luth-AR, for example, sells a separate .308/7.62 rifle buffer tube kit. See AR-10 vs AR-15 parts.
- Pistol builds. A stock on a pistol with a short barrel makes it a short-barreled rifle; see how to build an AR pistol.
Compare every AR-15 stock, check buffer tubes, and plan the rifle in the AR-15 builder.
Counting ounces? See the lightest AR-15 stocks and skeleton stocks, compared by maker weight.
Frequently asked questions
What is the difference between a fixed and collapsible AR-15 stock?
A collapsible stock slides on the buffer tube to adjust length of pull. A fixed stock has one length. Fixed stocks come in carbine and rifle-length versions.
What is an A2 stock?
A fixed rifle-length stock from the A1 and A2 rifles. It mounts on a longer rifle-length extension tube. Magpul's MOE Rifle is a replacement for it, with a length of pull of about 13.4 inches.
Can I put a fixed stock on a carbine buffer tube?
Yes, if it is a fixed carbine stock such as the Magpul MOE Fixed or the Strike Modular Fixed. Rifle-length A2 stocks need a rifle-length tube.
Do I need a different buffer for an A2 stock?
Yes. Rifle-length tubes use a rifle buffer and rifle spring; carbine buffers are not interchangeable. See our buffer weights guide.
Can I use a fixed stock on an AR-10?
You need a stock and tube system made for the AR-10, with .308 buffer parts. Check the maker's compatibility notes before buying.
Is a fixed stock lighter than a collapsible one?
Not necessarily. Magpul's MOE collapsible is 8.4 oz and its MOE Fixed Carbine 9.5 oz, and the A2-style MOE Rifle stock is 14.0 oz.
