COMBO ADJUSTABLE GAS BLOCK

By popular demand we've added a combination front sight gas block version of our standard adjustable gas block.  This block uses an AR-15 front sight post, allowing for lots of options for tritium and non-standard post designs like a forward ghost ring.  The windage is set using a standard AK front sight tool.  To set elevation, use the included front sight post tool to screw or unscrew the post to the desired setting.  Once the desired setting is reached, degrease and red loctite both male and female threads of the set screw in the drum and torque to 6-12 inch pounds, or approximately half an ugga-dugga.

The block is 100% made in the USA from 4140 steel (body), 17-4 stainless (gas valve), INCONEL X750 (spring), and A2 tool steel (detent).  The spring is rated for 1100F, which occurs when the barrel is glowing bright orange.  This is hard use gear by design, verified by actual testing.  The body is finished with nitride, which is extremely hard and corrosion resistant.

The inside diameter of the bore is 15mm, standard for AKM, AK-74, and AK100.  This part may work with heavy modification of the barrel on RPKs, VEPRs, Milled AKs, etc., but is not guaranteed.

Rather than using the usual set screw to moderate gas flow, this design utilizes a gas cup with multiple aperture sizes around the rim.  This cup, combined with a detent, allows the user to select between discrete sizes.  The design has no screws; nothing to come loose under high temperature conditions!  The gas cup design borrows heavily from historically rugged designs from HK, SIG, AK-12, and FN.  As all gas blocks accumulate carbon, we've designed in a removal feature so that the cup can be removed from the front by rotating to the section of cutout flange and pulling towards the muzzle end of the barrel.

PATENT PENDING

SPECIFICATIONS:

• 4140 ALLOY STEEL HEAT TREATED AND NITRIDED BODY
• 17-4 STAINLESS STEEL HEAT TREATED APERTURE CUP
• DRILL LOCATION IN 45 DEGREE (AKM) LOCATION
• INCONEL 1100F RATED DETENT SPRING
• 0.591" NOMINAL INSIDE DIAMETER OF BARREL BORE
• The easiest way to reduce excessive interference on the barrel bore diameter is with an adjustable lap. You can get a good one at Mcmaster-Carr.  The mcmaster part number for the lap is 4548A23, and some good diamond compound is mcmaster part number 4428A19 .  The diamond paste is a bit spendy—more economical aluminum oxide or silicon carbide compound works as well.  You only need a tiny amount of diamond paste—no more than the volume of a pea (though you’ll need to add more over time).  To size the bore up, rub compound then drip oil on the lap, chuck it in a drill, and spin at a moderate RPM while stroking the lap in and out of the barrel bore, evenly across the length of the lap.  You’re likely to not have any resistance at first.  Tighten the screw on the end of the lap by about 1/16 of a full turn.  Repeat this process until you feel mild to moderate resistance to holding the gas block still while the drill is spinning.  Ideally you want to cradle the gas block so that it aligns to the lap, and the only thing your hand on the gas block is doing is resisting the rotation of the block.  Once you’ve run the lap for 30 seconds or so with moderate resistance, the part should be getting a bit warm.  Pull a rag through the bore, and try banging it on the barrel again. Repeat the above till you feel the block smoothly hopping up the barrel with every hammer blow.  The barrel should be in a vise—never put hammering or pressing load on the receiver.