Gas block options

Jun 14, 2017
I have narrowed down my search for a gas block for my 308ar build to a slr sentry 7 adjustable. Anybody using one? All my research brought me to that one but not sure if I need the clamp on or set screw option. I will be running a 18" JP light contour barrel with a rifle length gas tube. Any advice would be much appreciated.
Jan 25, 2013
Tempe, Az
I would look at the inner diameter of the hand guard you'll be using and the size of the gas block and see which one will fit. JP doesn't dimple its barrels for the gas block. They may do it if you ask them to. I had to use the Sentry 9 gas block and had to go with the set screw model because of the inner diameter of the hand guard I was using.

If you do go with the set screw model and JP won't dimple it for you make sure you go with a good gunsmith. It doesn't seem like it should be all that hard to do but the gunsmith I took mine to screwed it up and dimpled it too far away from the shoulder and the gas block partially covered the gas port on the rifle and was blocking about half of the gas port. Had to go back and have him redo it after fighting with him about why my rifle wasn't cycling properly.
Jun 14, 2017
The ID for the AP m5 handgaurd is 1.72. The slr clamp on is 1.44 so I'm hoping I'll be ok. i was hoping to not have to go to a gunsmith.


Staff member
Mar 13, 2013
Southeastern, Pennsylvania
Fyi I run 8 or more SLR AGB. Mine seize up and after stripping screws and having SLR send me rebuild kits they told me to use the small end of the supplied wrench instead of sticking the long end straight in and to always turn it out when seized, not in. Breaks free every time now following this direction. Actually did it yesterday on a seized AR15 that wasn't tuned for my can.

unfortunately to use the wrench this way most times you will have to remove the Handguard.

I've used all the agb out there, they all seize.