02-26-2014, 05:58 PM
I use them all. For a precision gun, a set screw gas block that is bedded and has some method of securing at least one of the set screws into the barrel underneath is fine, especially when the gas block is underneath the handguard.
On my 16" Grendel with AA barrel, I currently have a clamp-on JP gas block that I machined down, made lightening cuts to on the sides, re-profiled the front of the block at an angle, blasted, and Cerakoted. I've never had that gun choke unless I tried a Magpul PMAG as a test to see if 3 rounds would feed.
For an exposed, standard Front Sight Base, you of course will want it pinned, as there is leveraging opportunity for the FSB to torque and come loose if it was set screwed, but I doubt many people will be installing standard FSB's on these Lilja barrels.
I think clamp-ons are probably the best method for getting a uniform seal around the gas block journal, and I haven't seen one come loose. You might also consider Loc-tite compound on the machine screws that clamp the gas block around the journal, and use an inch pound torque driver to balance the compression of the gas block around the barrel.
When installing a gas block, we tend to make assumptions that all the parts on the market should fit, however, a good AR15 smith or hobbyist will measure their gas block journal, as well as the ID of their intended gas block. Many need reaming, but reaming too much can bite you in the bung. I have also temp-fit gas blocks and barrels, where the journal was slightly too large. Place the barrel in the freezer, and heat up the block with a hot air gun (not open flame). Then quickly fit and trouble-shoot the parts. That makes for a very secure set screw gas block to barrel install.
On my 16" Grendel with AA barrel, I currently have a clamp-on JP gas block that I machined down, made lightening cuts to on the sides, re-profiled the front of the block at an angle, blasted, and Cerakoted. I've never had that gun choke unless I tried a Magpul PMAG as a test to see if 3 rounds would feed.
For an exposed, standard Front Sight Base, you of course will want it pinned, as there is leveraging opportunity for the FSB to torque and come loose if it was set screwed, but I doubt many people will be installing standard FSB's on these Lilja barrels.
I think clamp-ons are probably the best method for getting a uniform seal around the gas block journal, and I haven't seen one come loose. You might also consider Loc-tite compound on the machine screws that clamp the gas block around the journal, and use an inch pound torque driver to balance the compression of the gas block around the barrel.
When installing a gas block, we tend to make assumptions that all the parts on the market should fit, however, a good AR15 smith or hobbyist will measure their gas block journal, as well as the ID of their intended gas block. Many need reaming, but reaming too much can bite you in the bung. I have also temp-fit gas blocks and barrels, where the journal was slightly too large. Place the barrel in the freezer, and heat up the block with a hot air gun (not open flame). Then quickly fit and trouble-shoot the parts. That makes for a very secure set screw gas block to barrel install.