Guys I’d like to hear some opinions.

I’m thinking about converting my stock carbine upper into a mock dissipator, by replacing the a2 front sight with a low profile gas block, then mount a separate gas block with the handguard cap to where I can fit a rifle length a2 handguard, then mount a impact weapons components TMC flashlight mount on the a2 handguard or something of the like.

I’m doing this mainly because I’m not too satisfied with the carbine length handguards and I don’t have the proper tools to switch from a drop in handguard to a freefloat rail without pulling a muscle, and I’m a little convinced that it’s cheaper than buying a freefloat rail. I do have a magpul SL handguard but I like weird things, hence why I want to convert to a mock dissipator. I can always go back to the classic stock carbine just by switching out a few parts.

I also plan on getting the Primary Arms 1x prism sight when it releases for sale later this year.
I just want to know if this conversion will be worth the trouble, so give me suggestions or try and convince me not to convert aa carbine upper to a mock dissipator.



What I plan on using:
-YHM gas block/flip up front sight
-A2 rifle length handguard
-Impact weapons components TMC flashlight mount (or mod a magpul MOE picatinny rail adapter to fit the A2 handguard which I’ve done before, then add a low pro offset flashlight mount)
-Recycle the existing round handguard cap
-Any Low profile gas block
-A sacrificial gas tube to hold the handguard cap

Sounds like a fun project.

Do it!

Is the barrel .75" where you want to mount the fake gas block? I think there's a shoulder that sandwiches the front grip cap behind the gas block too.

To save some money, you could probably just cut/grind the sight and bayonet lug off your gas block. It will be hidden by the fore end anyway.

It would be way easier to just buy a freefloat tube and pay somebody to mount it for you.

Or buy a cheap dissipator upper for $200 http://palmettostatearmory.com/psa-16-mid-length-freedom-stainless-steel-1-7-moe-dissipator-without-bcg-or-charging-handle-43632.html

I was thinking about preserving the a2 fsb in case i wanted to go back to a standard carbine by taking off and switching out a few simple pieces with simple tools. I’ve always wanted to try the dissipator look and I have enough freefloated uppers already.

If you’re looking for a super easy to install free float rail, check out the DD Omega (not the X version). Installs on the stock barrel nut with supplied hex wrench and a screw driver. The “hardest”part is removing the stock hand guard.

Unfortunately that Daniel defense rail is kinda out of my budget. The YHM gas block/front sight is quite enough already and it’s only intended purpose is to serve as a fake gas block and to hold the a2 handguard I plan on mounting.
However I’ve always liked the shape of the Daniel defense quad rails and hope I’ll get my hands on one down the road.

I just want to put a rifle length handguard on the upper with the least possible effort and cost.
There’s still a lot of time to convince me into different options or to completely give up.

my experience has been that the process of knocking out the taper pins on the A2 FSB is the hardest part of the task, and that's where I thought you'd be likely to "pull a muscle".  at least, that's the hardest part for me, having to really wail on that sucker, and of course, whacking my hand or my fingers because of my piss-poor shaky aim.  But I gather that you don't have the clamp or vise or jig or reaction rod and barrel nut wrench for removing the barrel nut.  okay then.

I'm not sure if you'll need a make-believe gas tube to keep the cap from rotating.  the rear of the handguards locate off of the teeth on the barrel nut, and the front of the handguard, whether round or triangular, has some devices to locate the handguard cap.  As long as the barrel diameter fills the HG cap hole fully, i.e. .75"

and as mentioned above, whether the barrel diameter is .75" to support the relocated A2 front sight gas block.  With the drop-in HG, you might still experience some wiggle, especially if you use a front vert grip, depends on the brand, how they lock it up, etc.  at least, that's been my experience.

I’ve punched out taper pins from an a2 before and it wasn’t too hard, but not every AR is made equal.
I’ll be mounting a “fake” gas block in front with a chopped down gas tube to hold that front handguard cap just to put my mind at peace. As for the vertical grip I’ll be modifying a magpul moe picatinny rail adapter to fit an a2 handguard and a magpul RVG and if that’s too wobbly then I’ll just use a hand stop (I’ve done it before but again, not everything is made equal)

Isn’t the YHM front sight/gas block a clap on design? I don’t think I’ll need to worry about the diameter.
There’s someone on eBay selling used colt a2 handguards for about $23 or something like that, or my other options are del-ton and PSA.

Unfortunately that Daniel defense rail is kinda out of my budget. The YHM gas block/front sight is quite enough already and it’s only intended purpose is to serve as a fake gas block and to hold the a2 handguard I plan on mounting.
However I’ve always liked the shape of the Daniel defense quad rails and hope I’ll get my hands on one down the road.

I just want to put a rifle length handguard on the upper with the least possible effort and cost.
There’s still a lot of time to convince me into different options or to completely give up.

Gotcha. Yeah, that rail isn’t cheap. I have it on two guns. One muddy and one carbine. Super easy to install. Actually had a tough time finding it in stock.

I always thought the dissy concept was interesting. Longer sight radius and the rifle length. However, I was more interested with the performance of the rifle length gas system and your mock dissy would be more for the sight radius and look. Still interested in how it will turn out. Good luck!

Alright I went ahead and ordered the major components minus the flashlight mount since I didn’t get much opposition. Hopefully everything will work out and I’ll try to remember to post a picture and my progress.

Yeah yhm usually makes a .75 clamp on with sight gas block. Usually after the gas block journal it usually becomes thinner.

Iirc they dont make a gas block with flip up sight in .625.

Measured the diameter yet?

Well anyways what i was trying to say was that where the fake gas block will go may infact be .625 like mine. I was gonna opt into buying a gas block with rail and gas block height flip up front sight and dump the a2 style front sight/ gas block.

A real dissy is kind of a pita to run with different ammo reliably. Best option is not to overkill the gas port diam. But make it slightly bigger since the dwell time is hella short. And maybe a "lighter" buffer. Around 3.5-4.2 oz may be good. Windham makes one i believe or atleast use to. Dunno if they still do.


Keep us posted! Interested in seeing yours. maybe ill post up my mock dissy one day. Lol

Yeah it’s at 0.75”
I actually have a one of those picatinny rail/gas block you speak of, it came with one of my uppers sitting in the spare parts box but I think the YHM gas block/flip sight looks cooler. Looks has to matter too.

Nice nice. Yeah looks matter. I have a free float rail on it cause it was the cheaper route. Kinda wish i saved up and got a kac rail or something. Too little too late for me but good luck with yours!

I had to google what a dissy is.  And it looks pretty cool.

That's a lot of work to Barbie up a tool.

Can’t be too hard to swap out a a2 fsb with a low profile gas block and mount a 2nd fake gas block forward to accommodate a rifle length drop in handguard.
Easier than switching between barrel nuts and I already have two freefloated uppers that I use.

Thats unless you can source me a affordable lightweight extended drop in quad rail for a standard carbine upper which was my original intention before considering in a mock dissy. I was going to get a Midwest Industries extended drop in quad rail but it seems that they don’t make them anymore.

Anyway I’ll let you all know how it goes and how much effort it took.

I have seen some KAC RAS for sale on ar15.com some go for less than $100
DD Omegas too.
Several companies make carbine drop in rails. MI. Daniel Defense. Yankee Hill
The handguard cap rests on a shoulder on the barrel - how will you maintain that?

I thought one of the trademark characteristics of the Dissy was the way-forward A2 FSB, right behind the A2 FH.  yeah, they sure do look cool.  very "business" like.

I have the YHM clamp-on front sight block on one of my uppers also, I like the picatinny on the bottom, handy for the bipod off the bench (for me).  I got the one with the HK style hooded sight, semi-circular.  realized belatedly that it's also AK style.  oh well, international flavor.  they work pretty good, but it takes some tedious juggling (at least in my case), to get the sight damn straight precisely vertical so you don't have to crank the rear windage all the way to one side, and also to get the side-to-side gaps on the clamp even.  the intersection and overlap of those two independent universes was hard for me to capture.  although the latter is just a beauty touch.  I'm sure there's probably some simple elegant way to make all those planets align, bada-bing, bada-boom.  but I'm not privy to that craftsman dark trade secret.

USED rifle M5 KAC RAS's usually goes for a lot less than the carbine KAC RAS, I've seen.  lightweight?  hmmm maybe not so.

I’ll be using a separate gas tube that I’ll cut down to hold the handguard cap in place, or at least that’s what I have planned.

Dollar for dollar the complete PSA dissy upper is a far better deal.