Went to install my new NEA rail set today (swapping out the bonesteel), and the bolts/screws included to install the short rails are not the correct spec...
They are 17mm in length from top of head to bottom of screw/bolt. Previously, I have ordered the same items and received 13.85mm screws/bolts measured the same.
I email SFRC to see if/how they'll correct.
And the screws worked to install the bottom rail, but the sides, the screws impacted the barrel before tightening down the rails. At this price, they should correct... Will loop back once I have a resolution.
Also, when installing these aluminum rails, I cannot emphasize enough the importance of greasing the backside of the rail and receiver where they meet. Saved me from filing the front end on both the bonesteel and NEA vs my somewhat ignorant first attempt.
1. Grease blue section of rail all the way from top to bottom, backside facing the receiver (didn't mark blue on the pic past the lug portion to not confuse/cloud the tapping marks, but from top to bottom of the rear you'll want to grease the full thing, including past the lug). You'll also want to grease the forward surface of the front lower receiver against which this piece will rest. So grease on both surfaces that interact.
2. Install green portion in your front lower handguard retainer (previously where I filed 1/8" or so off, but have since learned is unnecessary).
3. I've found it easiest to upend rifle (use a muzzle device or otherwise protect crown). So arrow would face down and also the direction you tap. You'll tap the lug surface indicated by yellow line. Your support hand will hold the barrel and lower handguard. While you tap w/ rubber mallet/gunsmith hammer, you'll squeeze with your support hand to install. Once you get it installed to the point where you don't have space to tap, a hand squeeze should seat the rest of the way, but if it doesn't, just tap from the outside bottom towards top to seat (tap area just above the yellow arrow head).
Super fast and easy install.