New to the forum. I've got a 1522 with the compensator. To use the barrel nut wrench, you first remove the compensator and then the plastic end cap because obviously the end cap is bigger in diameter than the ID of the nut tool. I'm asking to see if others would see a need for a different style end cap that would allow the barrel tool to slide inside the ID of the cap to reach the barrel nut. This would allow you to remove the barrel without taking off the compensator.

The factory flash hider has a larger O.D. than the I.D. of the barrel nut. The nut just wont go over the FH.
You could cut the 4 inner ribs and sand until smooth. Then the wrench would fit thru the end cap, without having to remove the end cap.
To machine or mold a replacement end cap could be a spendy proposition, but very possible with a competent machinist or molder.

If you make the hole big enough to clear the wrench, it wouldn't serve any purpose. Why not just remove it and run the rail free-floating? The compensator/flash hider is bigger than the hole the barrel goes through and would have to come off every time anyway.

The last 1522 I bought had a nut that wasn't tight. I don't know how often you would want to check the nut but if we made a end cap with a larger ID, then you could slide in the wrench to check it (without removing the flash hider). I would just as soon leave off the cap for myself but some people may like the look of having it there.

How about making the hole bigger and making a new barrel nut that extends forward over the barrel and has a nut that sticks out through the end cap? Then, you could just put a wrench on it and tighten it without removing anything or having to use a special wrench.

That would be weak, a little heavy and very expensive, Plus it would be a trap for dirt and grit. We are working on a new barrel nut wrench that takes a lot of factors into consideration.
Stay tuned.
The flash hider has to come off to remove the barrel, but not always to tighten the nut.

The endcap has at least 1 functional purpose. Even though it's not in solid contact with the barrel, it still limits the amount of off-axis movement or flex in the forend / guard. Not that most of us bang them around in use, but for example a sling mounted to the guard could put enough tension there to flex it and strain or fatigue the guard where it attaches to the upper. Basically without the cap, whatever forces the front of the guard is subjected to get amplified by about 9" of leverage. Offhand that doesn't seem like a good thing.

I agree.. It's not like a mil spec alloy free float that is bolted down solidly to an alloy upper.

Yeah, the polymer certainly locks up nice & tight, but ... well it's polymer.
I wish I'd thought to have a better look at the attach point when I had the guard off, but I was on a cleaning mission at the time. Barrel still had a bunch of that thick factory lube / preservative on it under the guard and after a few range trips it was like used flypaper down there. Oh the horror!

Has anyone been able to clean the barrel exterior without removing the handguard?

Don't know why you couldn't just wrap a rag around a cleaning rod, pop off the cap and swab it out. If it's covered with heavy lube maybe shoot some WD40 or whatever in there first to break it up.

Not elegant but works, thought perhaps someone came up with a trick

so does anyone know where to buy a new S&W M&P 15-22 handguard end cap