BROWNELLS - BRN AR-15/M16/M4 Buttstock Tool

This castle nut/lock ring wrench worked perfectly. I've only used it once so far, but it fit my retro XM177 style lock ring well and did not slip out. You can custom-fit the depth of the round pin to get the most bite into the round hole of the lock ring, but without marring the threads on your receiver extension or allowing the pin to slip out and damage the lock ring.

I'm the armorer for the largest Sheriff Office in Idaho. When working on AR15's this tool works the best of any other option I've used. Where other wrenches have sheared off it's lugs when trying to remove a castle nut that has been installed with lock tight. This wrench will get the job done. I've even had to put a breaker bar on this tool to get one castle nut off and it held up.

Great tool. Removes the lock ring on a SR15. Only wish is that the stock is more readily available

So I gave this 5 stars, despite my hiccup. This tool is great, it's really well made and feels incredibly sturdy. My hiccup occurred because I used it on a barrel nut, not a buttstock. If you're using this for your buttstock, no need to read any further... The Centurion CMR handguard does not come with a tool. Centurion says that you should use a buttstock tool to install the barrel nut since it is the same diameter as the castlenut on a carbine stock. The problem is that you have to use a tool that has one "nub" on it, not three like most others have. These "nubs" aren't meant to torque a barrel nut to 30ft/lbs. I used my generic amazon AR15 tool to install the barrel nut and caused the "nub" to break off. I bought this thinking it may work for me. This tool has a small replaceable pin (as pictured), which bent and became unusable almost instantly. Luckily, I was able to use a 1/8in punch in the hole perfectly fine. I'm still 100% happy with this tool, the pin broke because it wasn't designed for the torque but luckily it has a great design where you can replace the pin. Obviously, the only thing I would change about this is tool is for it to come with a stronger pin. However, if you're building an AR15 you should already have an assortment of punches, which you can use with this tool.

I purchased this tool with some concern. I have an older AR-15 that had a 2 position collapsible stock with the 2 round holes instead of the normal castle nut and were well staked in place. I had been told how difficult some staked castle nuts were to remove. A friend who has built several AR-15's suggested just cutting the castle nut with a dremel which would likely destroy the tube as well. I wanted to remove the parts but retain them for collectors purposes and switch them out for a current 6 position stock tube. I just clamped the lower receiver in a vise using Brownells rubber faced vise jaws and was able to remove the ring without damage to the lower or the castle nut. I did tap the wrench with a plastic mallet several times before attempting to loosen the castle nut. This tool worked like a charm and I have already told several other people how well it worked. Brownells guarantee gave me the confidence to try it myself instead of paying someone else to remove the stock nut for me.