I am planning on getting a new Bushmaster upper. I currently have a Dissipator and a Carbine. The carbine has a BM fixed collapsable stock, the Diss. a standard. Both are A2's. I want a flat top. Trying to decide between a flat top carbine or Dissipator that I can swap on one of my existing ones. Which would you pick. I plan on putting an Arms flip up rear sight on it, and possible a BM flip up front. Also on the possibility list is an RAS from Knights. If I went with the Diss. do you think it would look ok on the lower with the Fixed collapsable stock? I guess its mearly a cosmetic thing because both have 16 inch barrels, although the Diss. lets you use the sights a bit more effectively because of the longer radius. Need everyones thoughts.

My next upper will probably be an A3 dis. The longer sight radius is what sold me.

I'm trying to make the exact same decision for an upper purchase later this year.

My thoughts were:

Dissy Pros:

Better heat dissipation - which is a problem with carbines in general and from the recent Marine evaluation seems to be even more of a problem with RAS

Better sight radius in same barrel length

Dissy Cons:

Longer handguard means more weight forward and could mean an unpleasant balance. With RAS or a collapsible stock, this would be even worse.

Dissy Questions:

Since most of the BUIS were developed for the M4, would there be weird sight issues if they were used with the longer sight radius?

Since most of the BUIS were developed for the M4, would there be weird sight issues if they were used with the longer sight radius?

I am having a brain fart. BUIS??

Quoted: Since most of the BUIS were developed for the M4, would there be weird sight issues if they were used with the longer sight radius? I am having a brain fart. BUIS??

Butt Ugly Intuitive Sight!

I personally don't like the looks of the dissapator myself. But they say the increased site radius is worth it. Good Luck.

I have a carbine with the AK-74 break.  God I love it, and the break keeps people from getting too close and asking what it is. If I had to do it over again i'd skip the break and go with the dissipator.  The gun looks more balanced with or without a (fake) tele-stock. The only problem with the dissapator is that no one that I know of makes a lower rail or M-4 style handguards for mounting tech toys.

BUIS = Back-Up Iron Sights

The only problem with the dissapator is that no one that I know of makes a lower rail or M-4 style handguards for mounting tech toys.

Knight's makes a full-length RAS that I believe can be used on a Dissy; but I know Olympic offers the FIRSH in rifle length, Bushmaster offers the C-More Rail system in several lengths, and Fulton Armory has a system as well.

If you've got a lot of toys to hang on the front, you can definitely do it with a Dissy.

I have a pre-ban Sendra lower with a Dissipator upper and collapsable stock. The longer handguards and gas system work fine, but to me the looks of the stock just doesn't balance out with the rest of it. My .02.

You guys need to check the "gas system length" issue.
The Dissipator has the same short gas tube as the carbine.
The front sight/handguard length is what makes the Dissipator unique--it's just a sight platform in front of the longer handguards, which are covering the gas block/tube.
You get a longer, full sight radius with the Dissipator, which is the good feature about it.
I can't think of a bad feature.
If you'll be installing a flip-up rear sight, you might want that full sight radius.
A3 Dissipator is a great choice, considering you have the A2; and an A2 carbine already.
Weight difference would be negligible.

BusMaster, Thats kinda where I was leaning. I love my A2 Dissipator. Both my carbine and current Dissi shoot great. I love the may carbines and M4's look, but, my Dissi with its Wilson Combat muzzle break on it just has this look about it. Personally, I think the Dissi is a great Urban Combat Rifle, er, excuse me, Urban Sport Utility Rifle. You get the handiness of a carbine but the full length sight radius and very little exposed barrel to accidentally bump your hand against when its HOT! I think that a A3 model with an ARMS flip up rear sight, possibly a flip up front sight (what do you guys think of them), Trijicon Mini ACOG, either a Knights RAS or a Bushmaster rail forearm, a Wilsons Muzzle break, and a light of somekind on the forearm (maybe even the one from sure fire with the foreward grip) would make nt only an extremely versital, but awesome looking weapon.

Thanks for the clarification on the BUIS. Brain was just dead.

I have a BM dissipator with an M4 stock but it is a little front end heavy.
 I'm building a post ban M4gery so I may put a A1 stock on the dissipator.

I really like the dissipator though from a functional point of view.  I like the longer sight radius & the full length handguards.
I would think you could put a RIS or RAS on there.
 I wish I had spent the $50 extra for a fluted barrel to save a little weight.  If BM has these in stock (last I heard back ordered) I'd spend the extra $$ for it.