I served in VietNam in 1969-70.  I was issued an M16, but lusted after a CAR-15.  Fast forward 55+ years, and now I can have an H&R CAR-15 (OK, XM177E2).  It has a 12.7" barrel with a pinned and welded FAKE moderator.  Since the moderator serves no "moderating" purpose, why not just have a correct-looking shell over a 16" (or so) barrel.  That would avoid the loss of velocity from the shorter barrel, but would look exactly the same.  After all, it also has "fake" gov't markings, etc. so why should a non-moderator that doesn't moderate also require the shorter barrel?  What would be wrong with this?

I had the same question and posed it to a few machinists (though with a shorter-than-16" barrel). I was asking about the CORRECT-LOOKING one, not the ones that are more modern takes on the look of the XM177 flash hider.  The response was that the barrel would be too thick (even with a pencil barrel) to allow the bottom portion of the flash hider to slip over it, so for it to work, you'd have to turn the barrel down a bit.

Here's an example of one that's using the same principle:

https://innovativeindustriesllc.com/xm177-moderator-non-functioning-slip-over/

A less accurate, less expensive option similar to the old school DPMS unit…
https://tonyscustomsllc.com/product/ar-15-reverse-flash-hider/

I bought this slip over flash hider around 2010. Compared to the others it didn't look too bad. A year later I stamped it and had the barrel cut to 10.5"

I had the reverse one in the link on a clone, and it actually looked really good.   That said it was a heavy barrel not a pencil, pretty sure it would look like crap on that.

I have a Preban DPMS that was originally made like that, with a pencil barrel.
It’s an A2 style and looks decent.

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That's close, but I think he's talking about a correct-looking XM177 flash hider.  The one you have is not.  The correct one has a step down where the wrench flats are, along with adding a grenade ring (for the XM177E2).

The one you have is what's possible without needing to turn down the barrel diameter.

That barrel is a Colt not DPMS unless I misunderstood you.

You are correct. The otb shroud is original DPMS.
The barrel and rest of the upper assembly are Colt.
I bought from the original owner and was told it is as he purchased it.

Pictures were to show the step from the barrel shoulder and indexing washer when using a pencil barrel.

OP can use a Colt Match Lightweight barrel and not have the gap between the OTB shroud and the barrel.
It will require threading the end of the barrel to match the shroud.
This might allow the shroud to be machined for the grenade ring groove.

Absolutely true. Thanks for what you guys do for us.

Also, the whole "loss of velocity" thing is a non-issue on what is most likely not going to be a fighting gun. Even with that, MK18s seem to do all right in the fighting department with 10.3" bbls.

Ammo choices have improved from the VN days.

I had a slip-over faux Moderator on my Colt CAR-15 Sporter's 16" barrel circa 1984.

Nothing wrong with it. Kind of surprised that they aren't more common now. It was a very simple construction.

I think you can get a pretty good looking carbine, by using a mid length gas system with a 16" barrel and a shorter slipover..or use a shorter barrel with a pinned and welded FH

Great idea and a great looking rifle.

I did some work to my build this weekend finally. I had a 10.5 barrel with a .750 gas journal that I turned down to .625 to fit the front site post, and drilled, tapered, and pinned it. Need to black the barrel a little more.
I don't have a 50 post count so my pictures won't post unless someone approves them, but here's the links.

I like the looks.  I'm not shooting hundreds of yard with one.  Where I live it's about 100 yd. across the road/pasture to the trees.  About 100 yds. from the back of my house to the woods.  In the woods you won't be seeing anything farther than 60 or 70 yds.  This is a no rifle/shotgun with buckshot only part of the state.  So looking cool is still good enough.

My very first AR15.  I bought it because it looked cool (added the pistol grip, optic later.  It even has a two position stock on it.  It is more accurate than either of the M16A1's I was issued in the US Army in the mid 70's.  And that's why I started building my own, because dog gone it, they can be more accurate than the crap I was issued.

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The one I build because I wanted a cool looking 9MM AR.

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Got another one with an Aimpoint on it I take on most road trips.  No pics of it.  Had two AR15 .223 pistols and decided to make one of the look better.

LRRP98
"I did some work to my build this weekend finally. I had a 10.5 barrel with a .750 gas journal that I turned down to .625 to fit the front site post, and drilled, tapered, and pinned it. Need to black the barrel a little more.
I don't have a 50 post count so my pictures won't post unless someone approves them, but here's the links."


That's quite a good looking build. And the skills to use the lathe!!!