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How To Make A Hiflow Valve

I read about converting a regular gas valve into a hiflow valve on a discussion board and decided to try it out.

All you need is a normal valve (such as from an unmodified magazine) and a file.

I tried a homemade hiflow valve on my G18C with a metal slide installed. The homemade hiflow performs well, with the gun shooting noticeably harder, and of course in exchange it eats gas far faster. 🙂

Note that to install and uninstall gas valves on the magazines, you will require either a special tool or some ingenuity.


The original stock gas valve has four small holes drilled in it. To make it look more like a hiflow valve, we simply “enlarge” two of the holes by cutting out the brass separating one hole from its neighbor. Do this on opposite sides so that two neighboring holes become one large hole on each side.

The images above show a side and top view of a valve after having this modification made. The valve is mostly brass, which is easy to cut with a dremel cutting wheel or a hacksaw – or even a file. Be careful to clean the valve completely afterwards as you don’t want any brass filings to be in the valve! A good way to do this is to rinse with water and allow to dry completely.

Now the stock valve looks almost, but not quite like a real hiflow valve.

Here is the modification (top) along with the real thing (a Hurricane hiflow valve in this case). You can see there are some differences; most notably that the Hurricane hiflow valve looks overall sturdier. The left tip is larger on the real hiflow as well.