How about them Dissipators?

[Dr. Gonzo GED]

Hey guys, I'm doing the window shopping thing for an AR upper and these caught my eye:

http://www.midwayusa.com/product/840432/del-ton-dissipator-carbine-kit-ar-15-556x45mm-nato-1-in-9-twist-16-barrel-upper-assembly-lower-parts-kit-m4-collapsible-buttstock-pre-ban?cm_vc=subv1951250

Has everything I need (plus a couple redundant lower parts). And the price is allright! I'm, a complete noob though when it comes to AR's (this is my first one ever) so I need a little help on choices.

My question is; How reliable are these dissipators compared to the old stand by styles (Full length and M4)?

Is it worth the $$$$, or should I just buy an M4gery like everybody else?

[slamfire51]

I had one and see no advantage.
All you need now is a bolt carrier group.

[Dr. Gonzo GED]

I had one and see no advantage.
All you need now is a bolt carrier group.
Looks like it comes with a decent BCG:

The Bolt Carrier is machined from 8620 Steel for strength, incorporates a properly staked, chrome lined gas key, and houses a Carpenter 158 Steel Bolt that has been High Pressure Tested and Magnetic Particle Inspected to guarantee a consistent, structurally sound part.


Did you encounter any dissadvantages though? Some "internet personalities" have reported poor reliability due to rifle length gas system on a carbine length barrel. Buit the reviews on Midway are pretty darn positive. (To me the advantage is I can complete my AR for less than $500.)

Was yours ever finicky though? I'm more concerned about reliability than anything else.

[imanaknut]

The big advantage of the Dissipator is the longer sight radius over the standard 16 inch barrel setup.

[Partisan1983]

The biggest problem I have seen when it comes to Dissy's is who and how it was made.

All due to the length of the gas system. Some make it rifle length, other's go with carbine length.

The big question is which is better?

[slamfire51]

Looks like it comes with a decent BCG:


Did you encounter any dissadvantages though? Some "internet personalities" have reported poor reliability due to rifle length gas system on a carbine length barrel. Buit the reviews on Midway are pretty darn positive. (To me the advantage is I can complete my AR for less than $500.)

Was yours ever finicky though? I'm more concerned about reliability than anything else.

I was looking at the list of parts not the description. My bad.

Nothing bad, I just didn't like it. Personal preference.

[Dr. Gonzo GED]

The big advantage of the Dissipator is the longer sight radius over the standard 16 inch barrel setup.

Hmm. My shooting abilities are probably not developed enough for me to take advantage of the long range benefits.

The biggest problem I have seen when it comes to Dissy's is who and how it was made.

All due to the length of the gas system. Some make it rifle length, other's go with carbine length.

The big question is which is better?
Well, this one is made by Del-Ton and features a rifle length system.

Any thoughts?

[deth502]

longer sight radius's are advantages at all distances. its not a long range thing.

i hear that the longer gas system has problems due to the dwell on the gas port not being long enough. if this is the case, then surely a carbine length system would work better. either way, the carbine length system is certainly more tried and true.

have you tried pricing them right from del-ton? hard to believe theyd be any cheaper going through a middle man (havent checked myself)

[Partisan1983]

Well, this one is made by Del-Ton and features a rifle length system.

Any thoughts?


That's the thing...I have no idea???

I want a Dissy, but it seems like one RKI says go carbine length, while another will say go rifle length :conf44:

[Dr. Gonzo GED]

That's the thing...I have no idea???

I want a Dissy, but it seems like one RKI says go carbine length, while another will say go rifle length :conf44:
The old web crawl is leading me to believew that the problems with the rifle length system pop up with underpowered ammo. Makes me think it would rather eat 5.56 than .223. It's all just heresay and arm chair quarterbacking from me at this point though...

[Dr. Gonzo GED]

Nothing bad, I just didn't like it. Personal preference.
Fair nuff!

Not the most glowing reccomendation, but certainly better than "Charlie was all around and there I was, stuck in the mud trying to extract a jammed shell casing with nothing more than my teeth and a raging kill boner!!!!"

[Schuetzenman]

Rifle lengh gas system is what the AR / M16 system was orginally designed for. Internal case pressure should be lower an this should be easier on the brass and extraction force. Mid length, (9 inch spacing) gas sytems are a compromise between carbine 7" systems and 12" rifle systems. The Mid-lenght a.k.a. middies are getting more and more popular for 16 inch barreled short rifle / carbines. They help out with lower pressure in the case and a bit more delay in extraction, which helps to prevent tearing rims off cases and case stretching for reloaders. I have my own Mid length and it was converted to gas piston, it is very gentle on the brass, more so IMHO than my full length rifles are.

The longer Dissapator sight spacing help with sighting error and for older eyes, the ability to get the front sight post in focus. The down side is, hard to find a bayonet to fit one, though I have seen people mod M16 bayonets to work in them.

[Dr. Gonzo GED]

The Mid-lenght a.k.a. middies are getting more and more popular for 16 inch barreled short rifle / carbines. They help out with lower pressure in the case and a bit more delay in extraction, which helps to prevent tearing rims off cases and case stretching for reloaders. I have my own Mid length and it was converted to gas piston, it is very gentle on the brass, more so IMHO than my full length rifles are.
I'ver been eyeing the middies as well. (I like the versatility, and you can still get that cool "dissipator HG look" with a low-pro block and free floating rails.)

I'm reluctant to go with a carbine gas system because I don't have tons of money to throw into maintenance and from what I understand the higher preasures and higher heat wear out the internals faster.

What do you think would be best for a first time AR guy?

[Schuetzenman]

I personally won't have a 7" carbine gas system AR. Seen too many of them fuckup at the range. Stuck cases from torn off rims or extractors that simply slip off the rims. Never had that with the Middie even when it was impingment before piston conversion. If you want a light quick handling AR I'd look at a 16" mid-length model of upper. I'd also go light profile vs. all these HBAR types. The M4 profile is between the HBAR profiles and the light weight barrel profiles. You do it right and you can probably get pretty close to 6 lbs. for the weapon. My first 2 AR rifles were 20" full sized rifles, both HBAR types tipping the scales way over 9 lbs. each. Better for match shooting, not so great if you had to carry the weapon all day.

Maybe my attitude has change as I'm getting older now and what once felt light as a feather now makes me go hummm when I pick it up and shoulder it. I like lighter now and think this heavy barrel stuff for a general purpose AR is way over done. We don't get to own full auto versions of these things so the heavier barrels except for match shooting aren't really necessary IMO. If I was to set up another 16" middy, I'd go light weight barrel, 1 in 7 so I can shoot any bullet in it, Moe handguards and grip, CTR stock and the MOE + grip. I like the YHM flip up gas blocks and rears for BUIS, you opinion may vary.

Back to the Dissapator look, like I said the iron sights are going to be easier to see with the rifle length gas system placement. However if you're going flat top upper, not as big a deal as you may end up putting a dot sight on it anyway and the irons become your backup sights should the electronic sight fail.

[NewbieAKguy]

I've thought about getting a dissipator style upper myself Dr. Gonzo. I like the looks of the hand guards covering most of the barrel, the longer sight radius, and still having a 16" barrel but with a rifle length gas system. If me I'd go for a set of Magpul MOE rifle length hand guards to put on it, but just me :): http://store.magpul.com/product/MAG419/62

My question to S-man or others more AR technical savvy than I am is is there any difference of a rifle length gas system with a 20" barrel vs. 16" barrel operation wise? Does the extra barrel length help it run better than shorter length barrel with same rifle length gas system?

[FunkyPertwee]

Palmetto State Armory makes a dissipator upper with a mid-length gas system.

http://palmettostatearmory.com/index.php/ar-15-05/complete-uppers/premium-dissipator-madness-16-cmv-chrome-lined-stripped-upper-without-bcg-or-charging-handle.html

http://palmettostatearmory.com/index.php/ar-15-05/complete-uppers/psa-16-hammer-forged-midlength-dissipator.html

[deth502]

I'd also go light profile vs. all these HBAR types. The M4 profile is between the HBAR profiles and the light weight barrel profiles. You do it right and you can probably get pretty close to 6 lbs. for the weapon. My first 2 AR rifles were 20" full sized rifles, both HBAR types tipping the scales way over 9 lbs. each. Better for match shooting, not so great if you had to carry the weapon all day.

Maybe my attitude has change as I'm getting older now and what once felt light as a feather now makes me go hummm when I pick it up and shoulder it. I like lighter now and think this heavy barrel stuff for a general purpose AR is way over done. We don't get to own full auto versions of these things so the heavier barrels except for match shooting aren't really necessary IMO. If I was to set up another 16" middy, I'd go light weight barrel, l.

i concur. middys were hard to find when i got mine, they were the new thing on the block. all that was to be found was the heavy barrle version. dont like it. imo, it handles like shit with all that weight out front.

i saw a while back palmetto started doing other profile middy barrels. keep wanting to change it out, but theres always something else to spend the $$$$ on.

[Schuetzenman]

My question to S-man or others more AR technical savvy than I am is is there any difference of a rifle length gas system with a 20" barrel vs. 16" barrel operation wise? Does the extra barrel length help it run better than shorter length barrel with same rifle length gas system?

Yes I've mentioned the length of gas system in my posts here. Longer = easier on the case, extractor and extraction of the fired case. Stoner designed the system for a 20" barrel with the spacing and size of the gas port for that length barrel. Carbines with a port only 7 vs. 12 inches away from the chamber start to cycle, (extract) the fired case earlier, so early the sides of the casing are still pressurized against the walls of the chamber. This raises the forces needed to extract the fired case. Sometimes the rims rip or the extractors slip off the rim and leave a case in the chamber. To over come this stronger extractor springs and round and D shaped rubber washers have been developed to put more holding force on the extractor claw so it won't slip off the case rim. I personally don't trust the 7" gas sytems, as I've said I see way too many of them having stoppage after stoppage. The mid-length with gas port 9" down the barrel helps to lower pressure in the case by adding time between ignition and gas getting through the port and tube back to the bolt group. Still not as low or as long as the 12" rifle gas system but a lot better than the Carbine length 7" systems.

I didn't have a 16" barreled AR until I could get a middy. That rifle proved to me that the mid length gas even when original impingement system does work relaiably. It handled 55 gr. surplus to 69 gr. Sierra match loads I made up, zero failures to extract.
http://www.gunsnet.net/photopost/data/500/Mid_length_gas_system_small_image.jpg
Here it is as initially built up from a Delton Upper and Stag Lower. Socom Stock by Ace. Plus one last thing, Mid length takes a stock M16 bayonet and I loves me bayonets! :D

[NewbieAKguy]

Yup, I read what you said about explaining the pluses of running at least a mid-length system in a DI AR. My main technical question was the second question that you quoted:

what is the difference, if any, mechanically when using a rifle length gas system on a rifle with a 20" barrel vs. a 16" barrel? Are there any issues when running a rifle length gas system with only a 16" barrel and the gas port so close to the muzzle than compared to a 20" barrel?

Thanks for the plain speak with the technicals :). I've also decided to go mid-length gas systems, minimum for all my future ARs......even though my dpms with carbine length has been absolutely reliable since I've had it.

[Schuetzenman]

Yup, I read what you said about explaining the pluses of running at least a mid-length system in a DI AR. My main technical question was the second question that you quoted:

what is the difference, if any, mechanically when using a rifle length gas system on a rifle with a 20" barrel vs. a 16" barrel? Are there any issues when running a rifle length gas system with only a 16" barrel and the gas port so close to the muzzle than compared to a 20" barrel?

Thanks for the plain speak with the technicals :). I've also decided to go mid-length gas systems, minimum for all my future ARs......even though my dpms with carbine length has been absolutely reliable since I've had it.

I understand what you were after now. I would expect (thinking about this vs. actually having experience with it) the gas back to the Bolt Group to be a little less as the bullet will exit the barrel 4" after the port vs. 8" after the port in a 16" dissy barrel vs. a 20" rifle barrel. Assuming you don't have too weak a load it should still cycle just fine. One other thing I can mention as I've have had experience with it on that middy. The SOCOM stock I have on it is the same length as a 20" fixed stock buffer tube. I started out using a rifle buffer, wouldn't cycle except with 69 gr. match loads I had. 55 and 62 gr. M855 ball wouldn't cycle right. The 55 gr. loads wouldn't eject, the 62's would eject but not far enough to pickup the next round from the mag. I put in a Carbine buffer and it ran fine after that. My point is buffer weight can take a not cycling weapon and make it cycle just fine. These weapons are a balancing act of forces. Get them in balance and they should run reliably.