Posted by Austin Colomaio on Oct 6th 2022

What model MERC should I order?

When it comes to picking a MERC for your setup there are three major questions:

1. Rifle or Pistol?

2. Rear Sight Barrel Diameter?

3. Gas Tube Length?

1. Rifle or Pistol?

The main differentiating factor for the two models is the overall length.

- Rifle - 11.75" From Front of Receiver to End of the MERC.

- Pistol - 8.0" From Front of Receiver to End of the MERC.

Best bet to see which flavor of MERC works best for your build is to measure the above dimensions out on your gun and see which you like best. Things to take into account are how far out you want to be able to hold the rail, whether or not you want your gas block covered or not, how close you want the end of the MERC to your muzzle (WARNING - DO NOT have the rail go past the muzzle device as the gasses can damage the MERC).

2. Rear Sight Barrel Diameter?

We use the two most common Barrel Diameters for where the MERC attaches.

- Stamped (AKM) - 17.5 mm

- Milled - 18.5 mm

A word of caution. Not all stamped guns have a 17.5mm diameter and not all milled guns have an 18.5mm diameter. We highly recommend viewing our youtube video below. In short, measure the diameter of the barrel where your rear sight base attaches. This will tell you which version you need as far as clamp diameter. 

3. Gas Tube Length?

We currently sell gas tubes for the following styles of Pistol/Rifle.

- AKM 

- Draco

- Lynx

- Krink

The gas tube you choose makes no difference in the MERC rail itself . This only provides the correct length of gas tube for proper function. 

If you have any further questions please email us at