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M4 Buttstock Wrench
M4 Buttstock Wrench
M4 Buttstock Wrench
M4 Buttstock Wrench
M4 Buttstock Wrench
M4 Buttstock Wrench
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BROWNELLS - M4 Buttstock Wrench

20 Reviews
M4 Buttstock Wrench
Brownells #
080000670
MFR #
100254
UPC
050806006638
$69.99
Coupon Code
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Estimated delivery: Sep 17
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Specifications
Color:
Black
Make Model Fit:
AR-15.Universal;Colt.M4
Material:
Steel
Item Length (Inches):
7.125
Wrench Style:
Armorers
Quantity:
1
Restriction
Gun Tool Restriction:
Yes
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What is the BROWNELLS - M4 Buttstock Wrench?

BROWNELLS BUTTSTOCK WRENCH FOR CAR-15/M4

The Brownells Buttstock Wrench for CAR-15/M4 is a purpose-built armorer's tool designed for the installation, removal, and maintenance of collapsible AR-pattern carbine stocks. Engineered to engage all four notches of M4-style receiver extension nuts, this wrench provides positive, non-slip contact for efficient castle nut service while helping reduce the risk of damage to the receiver extension, lock nut, or lower receiver.

Machined from a single piece of heavy-duty steel, the wrench delivers the strength required for professional gunsmithing, armorer work, and firearm maintenance. Its dedicated four-tooth design transfers torque directly to the receiver extension nut, allowing secure tightening and removal without the slipping commonly associated with improvised tools.

In addition to its primary function, the wrench incorporates several useful armorer features, including a 1/2" square-drive opening for torque wrenches, a fixed-stock receiver extension remover, an integrated pry blade/screwdriver, and a hanging hole for convenient storage.

FEATURES

  • Designed for CAR-15 and M4-Style Collapsible Stock Systems
  • Four Precision-Machined Teeth for Positive Castle Nut Engagement
  • Engages All Four Notches on M4-Style Receiver Extension Nuts
  • Helps Prevent Slippage During Installation and Removal
  • Transfers Torque Directly to the Lock Nut
  • Integrated 1/2" Square Drive Opening for Torque Wrench Use
  • Built-In Fixed Stock Receiver Extension Remover
  • Integrated Pry Blade/Screwdriver
  • Heavy-Duty One-Piece Steel Construction
  • Convenient Storage Hole for Pegboard Mounting
  • Made in USA

SPECIFICATIONS

  • Brand: Brownells
  • Brownells Part Number: 080000670
  • Tool Type: Buttstock / Castle Nut Wrench
  • Compatibility: M4-Type Receiver Extension Nuts
  • Material: Hardened Steel
  • Finish: Black Oxide
  • Overall Length: 7-1/8" (18.1 cm)
  • Construction: One-Piece Steel
  • Steel Thickness: .312" (7.9 mm)

COMPATIBILITY

  • CAR-15 Style Carbines
  • M4 Pattern Carbines
  • AR-15 Rifles Equipped with M4-Type Receiver Extension Nuts Featuring Four Square Notches

The Brownells Buttstock Wrench for CAR-15/M4 delivers the strength, engagement, and versatility required for professional AR stock installation and maintenance. With its precision-machined four-tooth design, one-piece steel construction, and built-in armorer functions, it is an essential tool for gunsmiths, armorers, and serious AR enthusiasts.

See all of our AR15s and AR15 parts here.

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CAR-15/M4 BUTTSTOCK WRENCH REVIEWS

4.5
20 Reviews
5 Stars
70%
4 Stars
10%
3 Stars
20%
2 Stars
0%
1 Stars
0%
Reviews Summary
The CAR-15/M4 Buttstock Wrench is widely praised for its high quality and effectiveness in handling castle nuts on AR-style rifles. Users appreciate its solid construction and reliable performance, though some find it expensive and limited in versatility. Overall, it’s recommended for serious AR builders and armorers seeking a dependable tool for precision work.
What Reviewers Are Saying
Product Quality
75%
Customers frequently highlight the premium quality and robust construction of the wrench, noting its effectiveness in removing staked and stubborn castle nuts. Many regard it as superior to cheaper alternatives, making it a worthwhile investment for rigorous usage.
Ease of Use
60%
Reviewers generally find the wrench easy to use, particularly appreciating its 4-point engagement with castle nuts. However, some mention challenges with leverage due to a shorter handle, indicating a desire for an improved design for better handling.
Value for Money
55%
While some users express concerns about the price, most agree the wrench's quality justifies the cost. It's seen as a valuable tool for professionals and serious enthusiasts, despite being pricier than simpler alternatives.
Versatility
40%
Some reviewers note limitations in compatibility with certain buffer tubes, especially those with fixtures like the Magpul ASAP plate. Users seek greater versatility to handle various setups without needing to remove additional components.
Durability
70%
The wrench is praised for its sturdy design, capable of withstanding heavy use without failure. Reviewers emphasize its reliability over time, especially when dealing with tough tasks, contributing to long-term satisfaction.
5
Excellent tool,
Bottom line - use the right tool for any job. This is The Right Tool. I wish I'd found it years ago.
by CDR-C on January 12, 2022
Was this review helpful? 1
5
Professional grade
Professional tools, and pride in workmanship, yield professional results.
by Bill on February 15, 2021
Was this review helpful? 1
5
Best buttstock tool
Best product on the market for AR or any AR type rifles. I have used them in training and they were prefect no issues. Thank you
by Joe on August 03, 2020
Was this review helpful? 1
5
Robust and I will write another review
I bought this 2 years ago and today, I removed another Colt LE6920 receiver extension tube. To loosen the super-staked castle nut, no need to use a deadblow hammer (although you can use it too), I used a 1/2 " square drive breaker bar (24") this time and it was smooth as butter the castle nut came loose. Since the end plate is staked too much that it won't rotate that it contacts the thread of the buffer tube tightly. You need to pry out its bottom with something like a polymer flat head. I used one from industrial rectifier/battery flat-heat tool. Once the big detent of the end plate is lifted and clear, use a rubber hammer to strike it counter clockwise. Be careful not to lose the detent spring of rear takedown pin. Once you remove the buffer tube from lower receiver, you will USE this wrench for the castle nut to push the end plate off the buffer tube. Don't worry of scratching the buffer tube's thread, it is still deep and you can stil re-use it. This scratch would be beneath and won't be noticeable. Once the old endplate is off, use a toothbrush to clean the threads. Do the reverse of steps above to install your favourite endplate with sling mount and then torque to 40 ft-lb. It should only be done on a sturdy vise and lower clamped to it, not using lower vise block that will exert stress on the magwell when torqueing. I installed a CQD rearsling mount on mine. Good luck to your project!
by Kirby on January 02, 2020
Was this review helpful? 1
5
Great Little Wrench!
Expensive? Yup. Worth the price? Absolutely! Over the last couple years, Ive ended up with a couple of different AR combination wrenches but have never liked how they fitted. The wrenchs prongs were small and narrow and never really allowed a solid purchase on the castle nuts. I had eyes this wrench for probably two years and reluctantly decided to purchase yet another wrench. Within a day of receiving the wrench, I had three ARs where I needed this tool. The wrench, while maybe a little short, is very solid and allows a good purchase on the castle nut, even with a Magpul ASAP mounted.
by BB on May 16, 2019
Was this review helpful? 1
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