Gunsmithing Drilling gas block for set screw

[zepheris.hk]

Hey fellas,

I am looking to get my low-profile gas block drilled for a set screw on the gas port (to make it an adjustable GB).

I know this is probably more work then just buying a lo-pro adj gb, but none will fit under my rail. It'd be pointless to buy one and also have that one modified to fit. Would anyone happen to know of a shop or individual that is willing to do this?

I have a Noveske lo-pro gas block.

Any help would be greatly appreciated!

 

[2156SMK]

Re: Drilling gas block for set screw

I have done a few of these.
It's best to spotface with an endmill to create a flat surface to center drill and then drill/tap.
You need a bottoming tap to cut threads all the way to the bottom of the hole which should only be drilled to the far wall of the existing gas passage.
Anyone close to you with a milling machine should be able to do this for a 12 pack.

 

[zepheris.hk]

Re: Drilling gas block for set screw

Thank you for your reply. PM sent.

 

[308MAUS3R]

Re: Drilling gas block for set screw

http://www.midwayusa.com/viewProduct/?productNumber=775354
http://www.midwayusa.com/viewProduct/?productNumber=363956

Both of those will fit under a handguard easily.

 

[zepheris.hk]

Re: Drilling gas block for set screw

I bought both the PRI and JP lo pro ones without success. I'm running the Aero Precision COP mono upper. The AR stoner would work, but for $100.00 I'd rather just have my Noveske one modified.

 

[jonaddis84]

Re: Drilling gas block for set screw

Just did this to the picatinny block on my M&P, it was quite easy, just had to locate the hole perfectly. The diameter of the set-screw was exactly the same as the space between the ID of the block and the gas tube. Didnt have either a 8-36 tap or any 8-40 set-screws, so for now it has a socket head torx on it until I find a set screw.

Question though, the Noveske Switchblock, when you turn it to "OFF", does it still eject spent shells? I cranked the setscrew in all the way to shut off the gas flow (obviously not all of it since it will escape past the threads slightly) and it did not grab a new shell, but it did eject the spent casing. I would think the gun would just operate almost like a blowback action even with no gas flow.

It only took about 1/2 turn from bottomed to make the gun cycle with a can on, definitely nicer though, no gas blowback in my face, and the gun just sounds better.

I thought about getting creative with it, but gave up. Was thinking about turning a stepped pushrod basically, with detents in it to hold it in place. The first step would be very small diameter to allow almost full gas flow. The second would almost shut off the flow for suppressor use, the third would ideally shut off the flow completely. I just dont know if the block would have been wide enough to accomplish this and still have room for the detents to hold it in place.

 

[hdbiker1]

Re: Drilling gas block for set screw

Gas is still bleeding by. That is evident by the ejecting of brass, although short stroking. The platform will not act like a blowback because the carrier is basically independent of the bolt. The bolt will not unlock until the carrier is moved back to uncam the bolt. No gas, no carrier movement, no carrier movement no bolt movement.

 

[BasraBoy]

Re: Drilling gas block for set screw

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jonaddis84</div><div class="ubbcode-body">

Question though, the Noveske Switchblock, when you turn it to "OFF", does it still eject spent shells? </div></div>

From Noveske website:

<span style="font-style: italic">OPERATION:

The Switchblock is adjustable by rotating selector drum, which is locked in position during operation.

The Switchblock has three positions; Unsuppressed, Suppressed, and OFF.

The OFF position is intended for single shot operation to reduce weapon sound signature and control spent cartridge ejection. In the OFF position, no propellant gasses travel into the gas tube effectively halting the cycle of operation at the point of firing. </span>

Effetively the rotation of the selector switch is cycling between three different ports - presumably by either rotaing the gas tube or some form of sleeve over the gas port - possibly in the off position there is no port?

I've never disassembled one so would defer to someone who has for a definitive answer on how it achieves this.

On the set screw adjustable ones I have seen there is never a 100% airtight seal when the set screw is fully closed so some gas will always travel through the system - clearly enough to move the bolt sufficiently to eject the round but not enough to fully cycle the bolt and chamber a new round.