There are two ways to go when purchasing tools: heavy duty professional grade for daily use or light duty tools for weekend warriors that are used infrequently. Obviously, those of us in the gunsmith trade tend to favor the one-time purchase of a high quality product that will give a lifetime of service. Why buy a wrench more than once?
One tool unique to AR-15 type rifles that is required for assembly/disassembly is the barrel nut wrench. There are many options but the original G.I. armorer's wrench from the 1960s was a flat plate fitted with pins that slid into the teeth on the circumference of the barrel nut. Modern designs start with this concept and improve upon it.
Recently, a law enforcement armorer friend of mine stopped by to tease me with some really nice tools designed and produced by a local machine shop. I have a drawer full of various wrenches accumulated over 25 years of working on AR-15 rifles but a lot of them seemed like junk compared to the heavy duty tools this guy was showing me. I was determined to track down the manufacturer and purchase a set for myself.
2 Unique, LLC is a machining and fabrication shop in Windham, Maine that provides firearms manufacturers with parts and accessories. The owner, Vaughn Schafer, worked for Bushmaster for 15 years during the time they were located in Maine and he has personally assembled thousands of rifles, so he has a pretty good idea what tooling works well for high volume assembly.
The barrel nut wrench is very stout with triple the number of pins found on the original G.I. wrenches and a long handle made from solid round stock. Schafer designed the wrench with a lot of leverage; not because the barrel nut requires a lot of torque to install but rather to reduce fatigue on the assembler when he is wrenching together his daily quota of rifles. The extra leverage is also handy for disassembly when you encounter a very tight nut. My wrench was supplied in the white but he is looking at various coatings for future production.
2 Unique also manufactures a top notch castle nut wrench to fit the nut on carbine buffer tubes. This one slides over the nut and encloses it for a very secure fit, unlike the commonly seen wrenches made from flat plates that can twist out of alignment when torque is applied. I'm not aware of a vendor currently marketing the 2 Unique wrenches (Brownell's, are you listening?) but Schafer will gladly sell you some. You can email him with your request at firstname.lastname@example.org. Plan on $90 for a pair of wrenches plus shipping.
Another style of barrel wrench I really like is made by Precision Reflex, Inc.
This one is fully enclosed, so it may not be convenient when a pinned on front sight base or gas block is present. Available either with an integral handle or as a wrench head for attaching to a breaker bar, models are offered to fit AR-15s or AR-10s and the DPMS pattern .308 rifles. Buy them at Brownell's.
A castle nut wrench similar to the 2 Unique tool is offered by DPMS. It encloses the nut and the integral handle provides good leverage. Available from Brownell's for $25.99 retail.
Good tools will last you a lifetime and buying the right one the first time will save you from experimenting like I did and ending up with a drawer full you donÃt use.
The top three wrenches are from Precision Reflex, Inc., The middle two are from 2 Unique and are very heavy factory-style tools. The bottom one is a more conventional tool from DPMS.
Both the PRI and 2 Unique barrel nut wrenches rely on pins to engage the barrel nut. The PRI type must slide over the barrel from the muzzle, which can be a problem if a front sight is in place.
The castle nut wrenches from 2 Unique and DPMS both slide over and enclose the nut. The 2 Unique tool is well worth it if you do a lot of AR gunsmithing, Norcross says.
The 2 Unique castle nut wrench has a pocket machined into the back side to fit rifle length buffer tubes. The long, heavy handle gives lots of leverage for turning the nut.