Hey everyone, I got a 16" pencil barrel on a sale and want to put together a new upper, and was considering getting the PRI folding front sight/gasblock for it as well as throwing a Magpul SL middy handguard on it, but I see Magpul says it only works with the standard FSB.

Has anyone ever used this combo?

Haven't used it, but I don't see anything obvious why it wouldn't work.  That FSB looks to have very similar dimensions as an a-frame FSB.

My concern is the space between the bottom of the sight block and the inside of the handguard as the PRI looks to take up sufficiently more space than the standard A-Frame, due to the crossbolts.

Best I got...


Attached File


Granted that Magpul has clearly stated that the MOE SL handguard’s top cutout only clears the stock A2 front sight base. I have encountered a small clearance issue with the Yankee Hill folding front sight gas-block. This YH combo fits original MOE handguard but the front sight won’t fold all the way down with the longer SL model. All it needed to fixed was was just some quick trimming of the polymer material.

SOURCE

Thanks for that. I imagine its likely the model with the bayonet lug which looks to be pretty similar to the stock A2 when it comes to the bottom of the block.
I'm probably just going to go free float, and save this idea for a future build.

Honestly considering the cost of a quality folding FSB, you likely would be better off just floating it with a decent rail anyway.

What is the purpose/genesis for the build?  Style?  Or, substance?  There are advantages as well as disadvantages, re: free float vs fsb.  If you are going to use a rear peep, the front should be attached to the barrel.  If optic, is there really a need for a front sight anymore?

Bit of both. I've had free float setups with no irons on 'em. I've had pinned FSBs and carry handle uppers. Think I settled on going free float with no front sight like my last build.

There is no wrong answer, right?!?  Looking forward to the pics

The PRI front sight gas block is designed to work with either an end cap or the included spacer. I just looked at mine (installed on an upper with a rail) and the front sight when folded is slightly shorter than the length of the gas block. It looks like it should clear the SL handguard, but if it didn't minor fitting would work. Comparing it to pics of the YHM one shown above, it looks like the PRI mechanism sits a little farther forward giving more clearance than the YHM.


I built this one out of spare parts I had kicking around; the YHM railed gas block, B5 P22 grip, and B5 stock had to be ordered. I'm real tempted to swap my PRI front sight gas block onto this one as the main reason I ended up with the YHM as it was cheap on sale.