Questions about SLR gas block installation

daNattyFatty said:

Good morning all!

So, I'm about to order a SLR Sentry 6 to go on my 11.5" BCM upper (which I intend to shoot suppressed most of the time) and have a few questions about installation and testing.

I'm under the impression that my barrel is already dimpled (that'll obviously be verified once I take the current gas block off). Does anyone know if the set screw location on the SLR should match up with the current dimple and gas port? Secondly, once I have the new block installed, I want to test for function before using Rocksett on the set screw. Will I be okay with just hand tightening the set screw to get the gas setting correct and verify that the block is in the correct position, relative to the gas port? This would be my first time installing a gas block and I want to make sure all is well before I do a second dimple and pin it.

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ironpony said:

SLR dimpling jig. $30 and look at the different ways to check alignment. Someone more familiar with this may chime in soon.

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balttigger said:

On mine, I noticed one of the set screw holes lined up with the block port. I just spun the block 180 degrees, centered the barrel hole in the empty set screw hole and used feeler gauges to see what my offset was. Used a pencil to draw a line center to the bore and center on the block. Then when I installed, it was just line up the pencil marks, set the offset with the gauges and tighten.

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alucard0822 said:

One dimple should be directly opposite from the port, other is usually .400 or .450 away depending on spacing of that block. The SLR blocks gas passageway is really small, only a bit larger than the port in the barrel, so they have to be spot on when lined up. I do similar to balttigger, center the screw hole over the gas port in the barrel(block upside down), then mark the position and offset from the shoulder on the barrel, then mark the vertical center line of the block, and center line of the barrel ahead of the port. Slide the block on, position to the pre-determined offset from the shoulder, turn till the centerline marks on the barrel and block line up, then tighten the screw opposite from the gas port first, then the second, verify it's straight, check gas tube alignment in the carrier, then back the screws out one at a time and rockset / torque. Ideally you could verify alignment with a borescope, but this is about as good as you can get without one.

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