One of the tradeoffs with the AR15’s direct impingement gas system is that they tend to run better when regularly given a little love. Since the gas tube is venting directly into the bolt carrier, regular cleaning is important. The OST Wrench fills the need for a small but tough field tool for help with the basic maintenance and cleaning of the AR15 platform.


The OST Wrench manages to avoid the “jack of all trades, master of none” problem by focusing on tasks common to someone in the field with an AR15 type rifle. It works well on its focused list of tasks. For example, the handle of the tool fits inside the AR bolt carrier. When turned, it will scrape loose carbon buildup that is difficult to access without the use of a tool.



The pointed, finger-like end of the OST Wrench is a carbon scraper for the back of the AR’s bolt. The “finger” in the back of the bolt should be pushed in far enough so that the curved edge of the tool sits against the shoulder, right below the gas rings. Giving it a few twists will scrape loose an impressive amount of grime. The adjoining small claw performs a similar function on the bolt lugs, as do the holes in the handle for the firing pin.



As the name would suggest, the OST Wrench can be used as a castle nut wrench. We found it to also work on the UBR Gen2 stock, with Magpul’s provided adapter. While it is not a direct replacement for an armorer’s wrench, it does weigh a full pound less and would certainly be up to making a field repair.



The butt end of the OST Wrench has a small pry tool V-cut. We found it to work best as a fingernail replacement of sorts for helping to get things started or worked loose. There are also wrench cutouts for the standard oxygen bottle valve and screwdriver bits.  The bit wrench helps to snug up fittings with that final twist or when extra torque was needed to get things moving. It is not a replacement for a full sized screwdriver handle, but works well enough in a pinch.



The OST Wrench comes with an elastic band to lock it onto a single loop of MOLLE webbing. It is small and light enough to easily find a place on a pack, vest or range bag. As for build quality, it is laser cut from 0.075-inch D2 steel. This is the steel of choice for some makers of hard use knives and it also makes for a tough little tool. All things considered, the OST Wrench is a well thought out little tool that is not afraid to get dirty and earn its keep with AR15 shooters.




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