QUAD RAIL HANDGUARD FOR SIG 556 INSTALL

Install handguard cap (if desired) and muzzle. For grins, I took a punch and LIGHTLY angle punched the slot on the lock ring (on one of those slightly raised edges) clockwise (looking toward muzzle) to assure tightness. You'll notice that with the top rails (receiver and HG) aligned, the design of the barrel nut slots mates with the set screw which seats secure into one of the valleys. Re-install rail set screw (I used some blue loctite) on bottom rear rail. It doesn't have be super tight, but good and snug. Now tighten with the strap wrench that 30 (or so) degrees until your rails are aligned. Wrap the wrench strap around the HG rail that surrounds the barrel nut (this will minimize stress). You can keep backing off, retightening the lock ring easily until you're happy with the amount it takes to tighten to rail alignment. That 30 degrees (or so) will now be retightened against the lockring with the strap wrench. Play around backing off the HG about another 30 degrees further from rail alignment, then tighten the lock ring forward against the HG snug. This is where you use your 'estimation'. There will be a small gap (mm+) between HG and upper continuous rail. I found out you'll have problems with tolerances around your takedown pin space. Do not thread HG against upper receiver, even if it fits perfect.

QUAD RAIL HANDGUARD FOR SIG 556 FULL

Screw the handguard lock ring (threaded outside the bbl nut) full rearward toward the upper receiver to keep out of the way during HG install. I used 1 drop blue loctite on handguard threads. Handguard screws on to barrel nut (lots of threads). Remove the handguard set screw at the bottom rear rail. Install barrel nut/gas block&tube according to standard rules You will need a strap wrench (cloth one is best). So I thought to mention that (I have to remove 4 crush washers - my poor planning). THESE MUST BE INSTALLED BEFORE THE MUZZLE. They attach to the open end of the rail with 4 tapered screws (to prevent things from getting into the handguard area - if you desire), and the caps have 2 small set screw against the barrel. If you want them, ohhunts makes and sells them too. Mid $300's for 10 free float handguards.Д«ear in mind these are set up to receive the rail end caps. But the tubes all passed through and everything seats fine. The ONLY thing I found was a slight variance in the HEIGHT of the gas tube holes when torquing (the gas tube would tap the receiver entrance on the top side (I have a cheap flex video scope). Only thing is there is no instruction - though I watched an identical handguard install online (same mfr I presume). Finding these was an unexpected surprise.

QUAD RAIL HANDGUARD FOR SIG 556 PRO

I had inadvertently bought barrels with dedicated pinned low pro gas blocks, making free float a necessity. I think they may just keep these, unless very particular. Trying to keep the investment as small as possible (when sold, new owners will customize every part to their favor). The price for these rails is outstanding. At the time of this review I have all the ohhunt barrel nuts installed and 4 of the handguards. South Georgia & South Sandwich Islands (USD $)

Quad rail handguard for sig 556