Recently acquired this rail for the M4.

There is not a whole lot of options out there unfortunately for the M4 but Strike recognized that and released an MLOK variant.

The rail does not come with instructions but it is easy to install:

1. Break down the M4 and remove barrel.
2. Install the HAYL over the gas block.
3. Reinsert the barrel with HAYL handguard.
4. Guide the HAYL into the handguard retainer grove then line up the front.
5. Press the barrel all the way (just like you would with factory handguard).
6. Tighten your end cap.
7. HAYL comes with four anti-rotation set screws with supplied blue locktite...honestly...the HAYL did not move up and down once installed...only slightly right to left without the anti rotation screws.
8. Once the set screws are installed...enjoy the HAYL.

The HAYL looks awesome but better yet...it gives you MLOK flexibility...counts as 922r and provides much better traction for your grip. There are no sharp endges that makes things uncomfortable.

Another benefit I can see is that it can aid in airflow around the piston system over the factory style handguards.

I'd rate it 8.5/10...simply because it didn't come with a manual and the anti rotation screws are somewhat tiny so be careful not to lose them.

They make some pretty interesting stuff.

The minimalist stock they have coming out is pretty neat

So can the rail be installed and uninstalled if you use the set screws and back off just a fraction so they prevent rotation but aren't "clamping"? I also noted there is a huge scratch on Strikes demo gun mag tube. Is the rail prone to doing this?

Oh yeah. You can. I don’t see it causing additional scratches. When you back off the set screws and pull the barrel out...the HAYL rests on the gas block.

I think their demo gun was an LE M4.

As long as the set screws are not impinging, can it be removed? Or do they have to truly be backed off? I'd like to set it up like a trigger. Barely off impingement.

Also, can the shotgun be 100% stripped without tools still? Y9u say the rail rests on the gas block? It slides right off too, yes? Or is further something required?

You just back out each set screw 2-3 turns and it comes off no problem. You don’t have to remove the set screws all the way.

The rail only rests on the gas block when you remove the barrel...the rail never touches the barrel once installed.