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9/22/2017 12:11:25 AM
Posted: 8/23/2005 11:00:54 PM EDT
I have decided that's my next rifle project, 16" .308 with full length handguards - exactly like a 556 Dissy, but 308. You get the idea.

Has anyone seen one or done it? If so, is there a problem with the rifle-length gas system on a 308? I can't imagine why it wouldn't work, but I'd like to know if it's been done especially to see one.

I'll probably go with an Armalite lower, and build the rest unless there's a better way.
Link Posted: 8/24/2005 4:38:52 AM EDT

From what I have seen the shorter gas system has given folks more problems than the 20"...interesting idea. Do you plan to get a 20" and cut the barrel down?
Link Posted: 8/24/2005 9:07:35 AM EDT
What's a Dissy? Is it rifle length handguards on a 16" barrel?



Why not use the 16" gas system with a low profile gas block and put the rifle length handguards over it and use a front sight to retain them.

From the OlyArms Website:
"At Olympic Arms rather than cutting down a 20” barrel, we created a new 16” barrel and contoured the 16” gas system to accept a standard front sight base in the same location it would have been on a 20” barrel. Looking at our design, we have a gas block separate from the front sight base. The front sight base is not part of the gas system, but still holds the handguards and the front sight assembly. This successful Olympic Arms design has brought the Eliminator to a high standard among industry leaders in quality, reliable tactical AR systems."
Link Posted: 8/24/2005 4:50:21 PM EDT

Originally Posted By PK90:
What's a Dissy? Is it rifle length handguards on a 16" barrel?

www.olyarms.com/images/k7/k7-angle.jpg

Why not use the 16" gas system with a low profile gas block and put the rifle length handguards over it and use a front sight to retain them.

From the OlyArms Website:
"At Olympic Arms rather than cutting down a 20” barrel, we created a new 16” barrel and contoured the 16” gas system to accept a standard front sight base in the same location it would have been on a 20” barrel. Looking at our design, we have a gas block separate from the front sight base. The front sight base is not part of the gas system, but still holds the handguards and the front sight assembly. This successful Olympic Arms design has brought the Eliminator to a high standard among industry leaders in quality, reliable tactical AR systems."




That setup was called the "Dissipator" by Bushmaster, and the name stuck (kinda like a xerox copy), that's a "Dissy".

In any case, that looks like Oly's .223 version of Bushmaster's Dissipator 16". I'm wanting to do it on a .308 rifle, either by cutting down a 20" barrel or by having a custom 16" built with a shorter gas system, hence my question. Don't know which would be the more reliable method.
Link Posted: 8/24/2005 5:04:54 PM EDT
Great idea!

Carbine - Mid-Length - Full Length gas system, what length would work best? Thats a good question, the .308 pressure curve has to be different than the 5.56, my guess would be full length is best.

Some ARFCOM experts need to jump in here.
Link Posted: 8/25/2005 4:53:12 AM EDT

I would go with the 20" cut-down and keep the longer gas system.
Link Posted: 8/26/2005 3:53:24 PM EDT
[Last Edit: 8/26/2005 4:00:58 PM EDT by Spooky130]
Here's some pics from ADCO's industry forum...







What mags does this use? I remember one of the .308 ARs using modified M14 mags. I can't remember if that was because of the AWB and not having high-cap mags available. Are they still using M14 mags - those things are darn expensive for USGI ones and then you have to tack the modification costs on the top of that...

Spooky

ETA - Found this on MSTN's industry forum

13.2 Larue - this one looks good too...
Link Posted: 8/27/2005 3:23:19 AM EDT

The Armalite AR10 still uses what looks like a modified M14 mag but the mags are being made from scratch now instead of actually converting old M14 mags. New AR10 mags are in the $35 (+/-$5) range.

Rumor is ARmalite is getting close on their new design that eliminates the bolt-hold-open plunger.

Bushamster uses FAL mags and DPMS uses their own or the $125 original waffle mag for AR10s.
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