JMAC CUSTOMS GBC-13 FRONT SIGHT/GAS BLOCK COMBO WITH DETENT
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$119.95
MSRP
$119.95
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Updated
Aug 26, 2026
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Specifications
Brand
Description
JMac Customs GBC-13-With Detent Hole
This does have a Detent Hole in the Front
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 gunsmithing
Uses standard front sight windage drum and pin
Available with detent and spring at 12 o'clock location
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
GBC-13 is a copy of the East German 74nk Front Sight Gas Block Combo
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 JMac Customs for machining.
