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Posted: 2/13/2006 9:39:44 AM EDT

I have an AR15 with a 16" barrel and short handguards like this...

http://www.bushmaster.com/shopping/barrel-assemblies/Images/abbl-16a.jpg

I would like to convert it to a Dissipator style AR.

Would this work?

- move my current front sight further down the barrel
- install a Dissipator gas block
- install longer handguards

Is there more to it than this?

Any help appreciated!
Link Posted: 2/13/2006 9:45:42 AM EDT
Crop/shave down your current gas block/FSB & then just add either a new "bolt-on" gas block or another regular gas block up front.

Or you could just forgo the front FSB all together & just add a 12" (or longer) free-float tube after you've cropped/shaved down the original gas block/FSB... you'd want to add a front BUIS of some kind to the free-float tube of course.
Link Posted: 2/13/2006 10:48:35 AM EDT
the barrel profile would need to be .750 at the front so that the fsb would be able to hold tightly.



the only way i see is to use a freefloat tube and rail mounted front sight or replace the bbl.
Link Posted: 2/13/2006 11:02:29 AM EDT

Originally Posted By eklikwhoa:
the barrel profile would need to be .750 at the front so that the fsb would be able to hold tightly.



the only way i see is to use a freefloat tube and rail mounted front sight or replace the bbl.



He is soooo correct, I tried to attach a fsb near the end of my 16" bbl and it would not fit.

I even tried out a PRI bolt on, not enough on the end to hold tightly.

Link Posted: 2/13/2006 11:14:40 AM EDT

Originally Posted By John_Bennett:
I have an AR15 with a 16" barrel and short handguards like this...

www.bushmaster.com/shopping/barrel-assemblies/Images/abbl-16a.jpg

I would like to convert it to a Dissipator style AR.

Would this work?

- move my current front sight further down the barrel
- install a Dissipator gas block
- install longer handguards

Is there more to it than this?

Swap out the barrel for a Dissipator.

Any help appreciated!

Link Posted: 3/1/2006 5:04:48 AM EDT
Can I ask a stupid question? What is the advantage of a dissy?
Link Posted: 3/1/2006 5:07:43 AM EDT

Originally Posted By ROADKING4:
Can I ask a stupid question? What is the advantage of a dissy?




rifle sight radius and if done with rifle length gas system the recoil impulses is less and runs smoother.
Link Posted: 3/1/2006 5:13:58 AM EDT
Thanks, I just bought one from the EE. I just wanted something different. I have an OLD SP1, and a RRA Tac Entry, now a DPMS Dissy!
Link Posted: 3/1/2006 12:56:14 PM EDT
Dont most dissy uppers have a short gas system anyway? So how do you gain an advantage other than sight radius? To add a rifle gas system would be the same as buying a 20" upper and cutting and re-threading the barrel. Right?

Only asking because Im trying to learn myself......
Link Posted: 3/17/2006 3:12:44 PM EDT

Dont most dissy uppers have a short gas system anyway? So how do you gain an advantage other than sight radius?


I believe they do.

Another reason I want a dissipator style is to avoid accidental burns from a hot barrel. The full-length handguards serve as a heat sheild similar to this one on a shotgun...

http://www.epicycle.org.uk/images/m870-5.jpg

My daughter burned herself on my CAR barrel. I laid it on a table next to a plastic cup, which melted. Less chance of these bonehead accidents with a dissy.

Plus, I think they look cool.
Link Posted: 3/17/2006 5:30:56 PM EDT
Link Posted: 3/18/2006 3:19:28 AM EDT
To solve the problem of attaching a gas block to the barrel you could do it a couple of ways. You could have your barrel turned down to take a pencil barrel FSB (.625) or you could have a sleeve made and silver soldered to the barrel and add a .750 FSB over it. Unless you do the work yourself or have a buddy who is a machinist both might end up costing as much as buying a new barrel in the configuration you want.
The area where the FSB goes is .750 but the barrels are usually turned down anywhere from .010 to .050 smalled up to where the FSB mounts. Makes it easier to slide the FSB on wih out marring the finish I guess.
Link Posted: 3/18/2006 8:07:00 AM EDT
I took a Bushmaster post ban patrolman barrel and shaved the gas block. I bought a front sight base from Fulton Armory. It has four set screws that hold it in place. I used a small screw in the gas tube port to hold the hand guard cap in place.



GVS
Link Posted: 3/20/2006 6:12:04 AM EDT

Thank you for the assistance friends. I believe a conversion is beyond my limited abilities. I don't have a machinist friend.

I guess the easiest thing would be to trade my 16" upper for a dissipator upper. I know dissipators cost more. My 16" upper is a J&T kit with less than 200 rounds through it.

How much cash should I offer along with my Upper for a fair trade in the Equipment Exchange?

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