JMac - MDi-co

GBC-13 Gas Block - Without Detent Hole - Adjustable

(3 Reviews)
Current Stock:
3.56 Ounces
Windage Drum
Front Sight Post
Out of stock

Adjustable Version of our Popular GBC-13!

Includes Set Screw and Allen Wrench!

(G)as(B)lock(C)ombo(13) Collab with Sabrewerks13

Without detent hole

 The intended purpose of these is to adjust the amount of gas going into the system. Once you have achieved the optimal amount of gas we recommend using rockset or loktite to maintain the position.

PLEASE READ THIS FIRST: These come stripped, they do not include the windage drum, front sight post, or barrel component pins.

If you would like those items click on the links below and add them to your cart. 

This does NOT have a Detent Hole in the Front

GBC-13 is a copy of the East German 74nk Front Sight Gas Block Combo

  • Perfect for Pistol, SBR, and Rifle builds to lighten up the front end and give it a custom look
  • Fits common 0.591" gas block barrel journals 
  • Has 90* gas port and is a direct replacement for most 90* gas blocks, will work on 45* gas ports with minor gun-smithing
  • Uses standard front sight windage drum and pin (available for purchase here - Windage Drum Front Sight Post
  • Has built in cleaning rod holder
  • Cast in the US using Wax Casting techniques similar to the modern Russian barrel components
  • Machined in the US
  • 4140 Heat Treated to Rockwell 32C
  • Black Nitrided in the US
  • Weighs 3.59oz

We recommend having a Kalashnismith install.


It all started with a high definition scan of an original part from Larry Vickers, then we teamed up with Sabrewerks13 to oversee the casting process, and finally back to us for machining. 

Reviews (3)


Written by Josh Randall on Sep 14th 2022

I have found JMAC products to be in spec, and have an acceptable finish. They have functioned flawlessly in my experience. I plan to continue to use their products. Thank you.

Adjustable gas block

Written by David on Mar 14th 2022

We build custom AK-47 rifles. The JMac parts are always the ones we reach for first. You can't go wrong with these. Great fit, great function, and it looks cool.

gb13 and cs

Written by tony Smith on Feb 22nd 2022

I run hard shoot fast. 3gun is tough and takes its toll. adj gas block is a great add on and if your like me and damage one, JMAC will back you up.. It may have been a flaw in the part. It may have been me punchin through barricades. regardless. I have a replacement in time. Im good to go without missing a match. Ash is hot

Related products

Customers also Viewed