First AR Build Questions

[LRRPF52]

How's hive opinions on this M-Lok upper?

Also, how great is this upper build video?

https://www.midwestindustriesinc.com/pro...-crm14.htm

I like the MI handguards and have used many of them.

There are a few things I would mention with the assembly video that I recommend not doing, but it is overall a decent video.

1st: Isolate the barrel itself when doing any type of muzzle device work. That means the barrel is clamped, not the upper or a barrel extension insert rod like he used when he removed the muzzle device.

2nd: Barrel nut torque can be anywhere from 35-80ft-lbs, doesn’t have to be a specific number. Since there nut doesn’t have Armorer wrench teeth on it that have to be timed with the gas tube, as long as you’re 35ft-lbs or more, you’re fine. For accuracy related to barrel nut torque, the AMU did studies across large samples of rifles and found that the 20” government profile barrels shot better with higher torque, whereas the heavy competition profiles barrels shot better with lower torque values. Something to do with resonant harmonics that balance out like that.

3rd: Gas tube alignment needs to be trouble-shot with the upper upside-down and your stripped carrier inside so you can find where it won’t clip the carrier key. After you’ve measured the correct axial port location relationship between the block and the gas port, you will know where you need to place the gas block to have port alignment. I bed my gas blocks to seal off the gas system, but I prefer interference fit if I can get it. Most gas blocks are built to slip-on for the DIY-er, which isn’t helpful for the gas system because it promotes leakage.

Their basic approach is OK though for installing their product. Big thing is to remember the torque plate that fits inside the gap at the bottom of the handguard.

I also apply their supplied Blue locking compound onto the knurled surface of the barrel nut to prevent the handguard from slipping forward when shot with a bipod. They used to have smooth OD barrel nuts that would allow that to happen.

I also make sure the receiver face is square before letting the barrel go near the upper.