BROWNELLS - M4 Buttstock Wrench

Bottom line - use the right tool for any job. This is The Right Tool. I wish I'd found it years ago.

Professional tools, and pride in workmanship, yield professional results.

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

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!

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.