What do you guys think of Dissipator uppers?

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[ARCHIVED THREAD] - What do you guys think of Dissipator uppers?

Posted: 9/7/2010 1:47:37 PM EDT

I am working on my first build and have never seen one before until yesterday afternoon.

I'm liking it a lot!

Thoughts?

Posted: 9/7/2010 1:54:44 PM EDT

[#1]

The dissy is for someone who wants a 16 inch barrel with a carbine gas system and a rifle sight radius, and rifle hand guards. The Bushmaster has a shaved FSB under the handguards. The front FSB has no gas tube, just a roll pin installed into the gas hole to hold the triangle handguard cap inplace, Its not a bad setup, and can be made into some interesting configurations, with rifle lenght rail systems.

Posted: 9/7/2010 1:59:22 PM EDT

[#2]

I had one years ago and liked it.

Posted: 9/7/2010 2:05:12 PM EDT

[#3]

People seem to either love or hate the looks. For me, it is about functionality. I love the rifle length sight radius.

Posted: 9/7/2010 2:21:42 PM EDT

[#4]

Quoted:
People seem to either love or hate the looks. For me, it is about functionality. I love the rifle length sight radius.

This is what I am thinking.

Same sight radius, smaller package.

Posted: 9/7/2010 2:39:37 PM EDT

[#5]

I just pulled the trigger on the new upper from ADCO and I am glad I did. It has a mid-length dissipator, which I have seen no where else on a dissy unles you put it together on your own. I really like the rifle sight radius and the longer rail it pretty sweet as well. I have not gotten the time to do more than zero it but from that time I really like it.

I decide to put a TA31RCO on there as well

Posted: 9/7/2010 2:43:38 PM EDT

[#6]

i have built 2 with J&T kits, i abosutely love them. the heavy barrel seems a bit heavy after a afternoon of shooting but i love the accuracy. i sold one to a buddy that had to have it and the other is my truck gun. Bushamster now makes a light weight dissy upper, i would love to have one

Posted: 9/7/2010 4:00:06 PM EDT

[#7]

I like the longer sight radius better but now rarely use them.

Posted: 9/7/2010 4:04:25 PM EDT

[#8]

I have a hard time finding one with a midlength gas system. I would think that would make more sense.

Posted: 9/7/2010 4:13:33 PM EDT

[#9]

CMMG sells one with midlength gas.

16" midlength gas Dissy

Posted: 9/7/2010 4:46:52 PM EDT

[#10]

my bro's dissy, also an adco Cruiser barrel. Its my father behind the optic

Posted: 9/7/2010 5:36:06 PM EDT

[#11]

They just look right to me...and if it looks right, it is right. It makes sense as well. I'm stuck on A2 hand guards and the sight radius made this the default option for me. Mine's a rifle length gas system with an enlarged port but a mid length is really the right way to do it.

Posted: 9/7/2010 5:54:25 PM EDT

[#12]

Quoted:
They just look right to me...and if it looks right, it is right. It makes sense as well. I'm stuck on A2 hand guards and the sight radius made this the default option for me. Mine's a rifle length gas system with an enlarged port but a mid length is really the right way to do it.
http://i164.photobucket.com/albums/u40/Ricky_a_photos/IMG_1992.jpg

Why?

Posted: 9/7/2010 5:54:32 PM EDT

[#13]

I love them. Longer sight radius with the benefit of less hot barrel to burn yourself with.

Posted: 9/7/2010 7:52:00 PM EDT

[#14]

Quoted:

Quoted:
They just look right to me...and if it looks right, it is right. It makes sense as well. I'm stuck on A2 hand guards and the sight radius made this the default option for me. Mine's a rifle length gas system with an enlarged port but a mid length is really the right way to do it.
http://i164.photobucket.com/albums/u40/Ricky_a_photos/IMG_1992.jpg

Why?

Well, the long and short of it are that with a 16" barrel the carbine length is a little over-gassed with a longer dwell time, the rifle length tends to be under-gassed with a short dwell time, and the mid length is considered the best compromise for a 16-18" barrel. The carbine length is optimized for a 14.5" barrel, the rifle was intended to work with a 20" barrel, and the mid is becoming the standard for everything in-between.

There's some good info and graphs near the bottom of the page HERE

Posted: 9/7/2010 9:17:29 PM EDT

[#15]

Quoted:

Quoted:
They just look right to me...and if it looks right, it is right. It makes sense as well. I'm stuck on A2 hand guards and the sight radius made this the default option for me. Mine's a rifle length gas system with an enlarged port but a mid length is really the right way to do it.
http://i164.photobucket.com/albums/u40/Ricky_a_photos/IMG_1992.jpg

Why?

Well, the long and short of it are that with a 16" barrel the carbine length is a little over-gassed with a longer dwell time, the rifle length tends to be under-gassed with a short dwell time, and the mid length is considered the best compromise for a 16-14(for 18 its between rifle and mid - they have it called intermediate.)" barrel. The carbine length is optimized for a 11.5" barrel, the rifle was intended to work with a 20" barrel, and the mid is becoming the standard for everything in-between 14.5 and 18".

There's some good info and graphs near the bottom of the page HERE

Not all correct, I fixed it for ya

Due to the energy transfered into the action (pressure and dwell time), pistol gas system (on 5.56) is best for under 10", Carbine is optimal for 11.5" and best out to 14". Midlength is best from 14.5" out to about 17" Its ok for 18". Intermediate is perfect for 18". Rifle is best for 20"+

Posted: 9/8/2010 2:55:07 AM EDT

[#16]

Love it! More rail space to add stuff.

Posted: 9/8/2010 11:20:18 AM EDT

[#17]

So from what I'm reading, the rifle length gas system isn't suitable for a 16" barrel?

Posted: 9/8/2010 11:35:49 AM EDT

[#18]

I like them and I think ADCO makes the best one on the market.

Posted: 9/8/2010 12:13:23 PM EDT

[#19]

I have a 14.5" middy with a 12" DD Omega rail that I really like, I also have a 18" mk12ish clone that uses a rifle length gas system. I haven't had issues with the 14.5 middy but the 18" rifle fails to lock the bolt back with Wolf ammo, works great with everything that is full power though.

I'm thinking about doing a 16" 6.8 midlength dissy build using MOE components for one of my next builds. I've got the 6.8 marked lower but haven't started anything else yet.

Posted: 9/8/2010 1:56:38 PM EDT

[#20]

Quoted:
So from what I'm reading, the rifle length gas system isn't suitable for a 16" barrel?

Not without modification. It can work, but be unreliable.

Posted: 9/8/2010 2:54:05 PM EDT

[#21]

I would like to see a dissy with a light weight barrel and mid-length gas. If someone doesn't offer one soon I'll go ADCO and have them re-profile the barrel.

Posted: 9/9/2010 5:31:35 AM EDT

[#22]

I have a dissy upper from DPMS with a rifle length gas system and it's a tack driver ! I have over 2000 rds. thru her and it doesn't miss a beat. It's never jammed. That's bulls#*% it does not work with a 16" barrel. It's all internet talk,That's all...

Posted: 9/9/2010 6:05:53 AM EDT

[#23]

You just gave me an idea for my next rifle:

Flat top upper with 16" barrel dissy with Magpul MOE handguards....

Posted: 9/9/2010 12:21:16 PM EDT

[#24]

Quoted:
I have a dissy upper from DPMS with a rifle length gas system and it's a tack driver ! I have over 2000 rds. thru her and it doesn't miss a beat. It's never jammed. That's bulls#*% it does not work with a 16" barrel. It's all internet talk,That's all...

I think people are saying it's problematic to use a rifle length gas with a 16" barrel, not that it is problematic to use a dissy (which is carbine length gas).

Posted: 9/9/2010 6:25:20 PM EDT

[#25]

Quoted:

Quoted:
I have a dissy upper from DPMS with a rifle length gas system and it's a tack driver ! I have over 2000 rds. thru her and it doesn't miss a beat. It's never jammed. That's bulls#*% it does not work with a 16" barrel. It's all internet talk,That's all...

I think people are saying it's problematic to use a rifle length gas with a 16" barrel, not that it is problematic to use a dissy (which is carbine length gas).

It's not ideal, but properly tuned it works fine. It can be problematic with low powered loads, some have short stroking issues in extreme cold weather, and they can be more sensitive to fouling. It just takes some of the flexibility out of the system. On the plus side, they are very soft shooting and can be more accurate due to the low impulse. Mine has never given me a problem, but I've always fired the same ammo out of it.

ETA: If you're building from scratch or buying a new upper, there's very little reason to go rifle length gas. I went that route as I was pleased with the performance of the existing upper/barrel and couldn't afford to go with anything else.