Daniel Defense Mil-Spec Receiver Extension, Six Position

Product Description

The Daniel Defense Mil-Spec Receiver Extension, Six Position is a 7075-T6 aluminum buffer tube for M-4 and AR-15 type rifles and pistols, 7.25 in. long with a 1.15 in. mil-spec outside diameter, allowing six positions of adjustability with a mil-spec collapsible buttstock.

The receiver extension is the part nobody thinks about until it fails. It houses the buffer and spring, takes the buffer’s impact on every shot, and acts as the rail your buttstock slides on. A soft or poorly finished tube peens at the rear, wears at the detent notches, and turns a crisp stock adjustment into a gritty one – hence 7075-T6 aluminum with a Type-3 hard coat anodized finish.

The other reason people buy one is compatibility. Mil-spec and commercial tubes are not interchangeable: commercial tubes are larger, so a mil-spec stock will not fit them and a commercial stock is sloppy on a mil-spec tube. This is the mil-spec pattern at 1.15 in. outside diameter, which is what most quality aftermarket stocks are cut for.

Key Facts

• Brand: Daniel Defense
• Model: Mil-Spec Receiver Extension, 6-Position
• Manufacturer Part Number / SKU: 05-013-16186
• Material: 7075-T6 aluminum
• Finish: Type-3 hard coat anodized
• Overall length: 7.25 in.
• Outside diameter: 1.15 in.
• Weight: 4 oz
• Adjustability: six positions with a mil-spec collapsible buttstock
• Fitment: receiver extension (buffer) tube for M-4 and AR-15 type rifles and pistols; fits mil-spec buttstocks

Mil-spec versus commercial, in plain terms

Measure the tube you have, or the stock you want to run. Mil-spec tubes are 1.15 in. across; commercial tubes are larger, usually with a sloped rear face, and a stock built for one will not sit right on the other. Replacing a commercial tube means your stock has to change too. Browse stocks and stock accessories, buffers and buffer tube kits and stocks and buttstocks.

Ordering from Western Sport in Roanoke, TX

Western Sport, in Roanoke, Texas, has been a licensed FFL/SOT dealer since 2007 and is a Daniel Defense master dealer, so this extension comes to us direct. It is on backorder; call 817-393-4000 to have it ordered. Castle nuts want staking and proper torque, so our on-site gunsmith can do the install.

Frequently Asked Questions

Q: Is this a mil-spec or a commercial receiver extension?

A: Mil-spec. Its outside diameter is 1.15 in., the mil-spec dimension, and it fits mil-spec buttstocks. Commercial tubes run slightly larger and are usually slant-cut at the rear. If your stock slides onto a 1.15 in. tube it is a mil-spec stock and will fit this extension.

Q: How long is it and how many stock positions does it give?

A: Overall length is 7.25 in., and it allows six positions of adjustability with a mil-spec collapsible buttstock. Six positions is the common carbine layout and gives enough travel to shoot the same rifle in a T-shirt and in a plate carrier without fighting the length of pull.

Q: What is it made of and how is it finished?

A: It is constructed from 7075-T6 aluminum with a Type-3 hard coat anodized finish. That matters here: the buffer retainer, the buffer and the rear of the tube take repeated impact, and a hard anodized 7075-T6 surface resists the peening that turns a soft tube notchy.

Q: Will it work on an AR-15 pistol as well as a rifle?

A: It is specified as a receiver extension for M-4 and AR-15 type rifles and pistols, so the tube itself is the same part either way. What changes is what you fit to the back of it, and the legal status of the finished firearm depends on your configuration and jurisdiction.

Q: Do I need a castle nut, end plate, buffer and spring as well?

A: A complete installation needs a castle nut, receiver end plate, buffer and buffer spring in addition to the tube, plus a buttstock. We will not state what is packaged with this part number – call 817-393-4000 and we will confirm before you order so you are not a part short.

Q: How much does the tube weigh?

A: 4 oz. Worth knowing if you are counting ounces on a lightweight build, because the receiver extension is one of the few places where material choice and wall thickness show up directly in the number. Four ounces is a normal weight for a six-position 7075-T6 carbine extension.

Additional information