M16-A1 style Dissipator? Terrible idea?

[MatthewVanitas]

Greetings,
This is probably a dumb idea caused by procrastination and staying up late (no, not by drinking). I had been puzzling out the details of a Dissipator AR-15 project, mostly figuring out the best way to solve the "muzzle-heavy" feel many folks complain about with the Dissy.

I was just planning to get a Bushmaster Dissipator A3 upper, +$50 for fluted barrel, and slap my Ace Shorty Skeleton Stock onto a Stag Arms lower.

Then I saw CDNN's Colt SP1 uppers for $369, and my head was full of Vietnam retro-cool visions until I realized that they didn't come with bolt assemblies, so tack on another $100 or more just to get the upper running.

Then, in a burst of late-night idiocy, I envisioned a Dissipator with triangular hanguards and 3-prong flash-suppressor, A-1 sights, slabsided, with a short A1 buttstock, 20-rd straight mag...

The handiness of a 16" M-4gery, lighter barrel/sights/receiver, short stock, etc. I'm used to iron sights anyway, and would just set it for BZO and leave it be, so the lack of A2 sights doesn't worry me. Would probably go with the 1:9" twist for ammo flexibility though.

Common sense is intruding to say that this project would probably cost as much as my original Dissipator plan, plus nobody would ever buy it off me if I decided to sell it.

What says the crowd: terrible idea, or inspirational? -MV

 

[Zach S]

Sort of insprirational. I've thought about building a dissipator on an A1 upper.

 

[Feanaro]

I'd buy one! The light weight of the A1 style AR with the short and manuverable 16" barrel. All without losing sight radius.

 

[DMK]

It's a good idea. I've seen one or two over at AR15.com.

The only drawback is due to the 1/12 twist of the M16/M16A1 barrels, you'd be limited to 55gr ammo if that matters to you.

Another option is buy a standard Dissy barrel in 1/9 twist and have it turned down to the profile you wish.

 

[BIGPHIL]

I had one. The barrel was a bushmaster 20" that had been cut down. Other than that it was all A1 (upper, handguards, FS). Mine didn't have any sights on it. I just used it as a hip gun (shooting from the hip, bump fire). I was able to take it apart and sell the parts individually when I was done with it.

Do it. It will make a good conversation piece if nothing else.

 

[Bartholomew Roberts]

The problem with cutting down a 20" to a 16" dissipator is that you don't have enough barrel after the gas port for a good dwell time and you run into some of the same reliability issues that the 10" barrels have.

 

[MatthewVanitas]

Bartholomew: I wasn't so much thinking of literally cutting down an A1-style upper so much as building up an A1 style upper in proper Dissy format.

So the eventual upper would have two gasblocks: one non-functional at the 20" position to hold the frontsight, and a functional one below the handguards at the CAR position. Building from a Dissy barrel in the first place would also get me the 1:9 twist.

Does anyone know who sells slab-sided (forward assist-less) A1 uppers, 3-prongs, and the like? Do I need special handguard retainers to hold triangular handguards?

I'll have to go register on AR15.com to see those other A1 Dissy pics.

Glad it's not just my dumb idea, though a bit let down that it's been done before. -MV

 

[c_yeager]

Its been done quite a few times. I recall that there was an actual prototype carbine built along these lines in the 1970s. Some people have had success with simply enlarging the gas port of a cut-down 20" barrel and building a dissy type rifle out of it. You could also just use a ready made dissy barrel if you prefer. They are pretty neat looking rifles, especially with an A1 stock, or one of those shorty entry stocks.

 

[MatthewVanitas]

Good deal, just waiting on my AR15.com registration so I can use their search engine to research the topic.

Looking further into it, I realize that I'm visualizing the M16 (no suffix), with the 3-prong and no forward assist:

(Pic from http://world.guns.ru/assault/m16.jpg)

A slabside upper would be harder to find than an A1 upper (BM carries the latter). Would it be horribly inauthentic to have a 3-prong flash-suppressor with a old-style forward assist? Bearing in mind that "authentic" is pretty relative since the Dissipator itself is not a Vietnam-era conconction.

Mr Yeager: I don't suppose you have any pic of the short M16 prototype you mentioned? I was going to just PhotoShop myself an example, but this computer has no PS, so I just have to look at the M16 pic and use my imagination.

I do want to be modern "under the hood" though, so probably would stick with a modern 1:9 Dissy barrel, either fluted or M4 profile to save weight, since it all looks the same on a Dissipator anyway. I'm sure there's a parallel term for this in the automotive world, right?

Will post further once I get a chance to search AR15.com and see other folks' projects. -MV

 

[BIGPHIL]

I must have been lucky then. I had no reliability problems with mine and the standard gas port.

 

[Amish_Bill]

I have an old A1 upper that was chopped off at 16". To get it to run properly I had to enlarge the gas port.

If I could only get it off the upper it's on I'd consider having it threaded... (barrel nut is fused to receiver)

 

[rbernie]

MidwayUSA has one of the DPMS A1 upper receivers left in stock - it's not cheap but it is a new A1 upper receiver. You could always couple that with an Armalite 16" mid-length barrel (lightweight profile), low-profile gas block, rifle-length free float railed forearm, and rail-based front/rear sights.

 

[MatthewVanitas]

rbernie: Bushmaster has new A1 uppers for $145

So the BM is a fair better deal than the DPMS, but I do appreciate the heads-up.



Regarding the rails and such: I'm thinking that this would be the "un-tactical" AR-15, so no need for highspeed attachments. To summarize:

Either pre-A1 "slabside" receiver, or A1 receiver
Three-prong flash-suppressor ($9 on Gunbroker, mil-spec threading)
A1 buttstock if available, otherwise Entry solid stock.
A1 triangular handguards
Bushmaster 16" Dissipator barrel (two gas blocks), fluted or M4 profile

So the overall goal is to have something that looks as close as possible to a cut-short M16 (no suffix) or M16A1, but has a modern 16" 1:9 Dissy barrel for reliable operation, compatibility with wider ammo range, and the short-handling nature of an M4gery.

It'd be distinctively novel, yet have the same operation and easily handling as modern AR carbine, lacking only the easy adaptability of the highspeed gadgets that I wasn't planning on buying anyway. Off to AR-15 to do some research (and then back to working on my sociolinguistics paper on the Oakland School Board's resolution on Ebonics). Thanks for all the info thus far, and if anyone has advice on obtaining A1 or pre-A1 handguards/grip/stock, that'd be much appreciated.
-MV

 

[MatthewVanitas]

Getting some great replies from the ARF lads

No disrespect to THR; this forum is great and the quality of discourse exceeds almost every discussion forum I've ever seen, but they have some _hardcore_ AR buffs over on ar15.com

Dig the historical precedent attached below. I'm thinking pretty much like that, but with a Stubby buttstock...

 

[BIGPHIL]

I guarentee you can find that A1upper in the EE cheaper than $145.

ar15.com rocks

 

[modifiedbrowning]

Those old school Dissies look very cool. There is a guy over at ARF named Mongo that cuts 20" barrels down into Dissies and opens up the gas port a little. He has some nice looking rifles and I believe he has been selling some of them.

 

[LToled]

Fulton Armory

I have one of the Fulton Armory uppers that were A1s that were shortened to Dissy (16") length with an A2 FH. I think they called them Millennials. They used the standard length gas system instead of the carbine system. I haven't had a malfunction with it since I got it. I lost track of the number of rounds I've run through it. I don't think they sell them anymore but it's an extremely light and handy rifle. I kept it simple and only added a Hogue grip and a Sully stock.

 

[MatthewVanitas]

Man, those Sully boys are building pretty much what I want!

A1 upper with Dissy barrel. Only difference is that they use highspeed shorty furniture, I want retro shorty furniture.

Oh, and they also charge twice what I hope my project will cost. It's very possible that they're totally worth it, just a bit rich for my blood. Great pic though. It is quite cool to see a resurgence of the A1. They apparently also use a special rear sight flip-aperture with no loss of zero between large/small aperture. This project might get pricier than I thought...

Still torn between M16 vs. M16A1 upper, "to forward assist or not to forward assist". I was thinking to keep the FA for brasschecks: "slingshot, brasscheck, tap the forward assist, sweep sights, check sights"

Then geekwitha.45 brought up the fact that you can manually push the bolt forward with your pink or thumb. Now I'm not so sure as to what I want. Will have to ruminate on the idea over Christmas break.

Thanks for all the great info thus far. -MV

 

[sully]

A1 Style 16" Rifles with Full Length Sight Radius

If you like the one above you should check this one out: http://www.olegvolk.net/gallery/ar15m16/commander_green7943

We still offer the A1 upper receivers, but we have switched our main line over to an ambidextrous flat top upper receiver with an A1 knobless carry handle. This offers the best of both worlds IMHO. We also use a light weight barrel Wilson chromed lined barrel in 1/9 that is cut to our own profile.

If you are going to cut down an old A1 barrel then be extremely careful not to cut it too short as it will cause reliability issues, and if you are thinking of reporting then be cautious at the old A1 barrels are chrome lined as you do not want to mess up the chrome.

If you are wanting to keep it light weight then be careful of aftermarket barrels as many of them are heavy barrels, this is why we have Wilson cut to our own configuration. You will also find that balance to the rifle is very important, as many rifles are front end heavy, thus another advantage for a Sully stock.

CY6,
Greg Sullivan "Sully"
http://www.SLR15.com
http://www.TheDefensiveEdge.com

 

[MatthewVanitas]

Greetings Mr Sully: great site! I've really enjoyed drooling over your rifles.

Regarding cutting SP1s: though this has been suggested to me, I'm a bit leery of it, so planning to go with a Bushmaster M4-profile 16" Dissy, 3-prong flash-suppressor, screwed onto either an A1 upper or an M16 "slabside" upper. That way I won't be fiddling with the gas-system, just using a standard CAR-length system, and avoiding all the other issues you mentioned with cutting an SP1. Plus, the BM will be new and have a 1:9" twist, so good all around.

As mentioned in my other thread, mainly trying to figure out if a slickside upper would be simpler than an A1. It mainly comes down to whether or not one can easily push a bolt into battery by sticking one's thumb through the ejection port, after a brasscheck (presscheck). That seems to be the main application of an FA, so if it can easily be done with finger, I'll skip the FA.

Best of luck on your ongoing development; I'll be following your site with interest. -MV

 

[sully]

My suggestion is to go with an upper receiver that has a shell deflector, as you should learn to shoot efficiently off of both shoulders, as the shell deflector is a nice feature when shooting as a lefty. On the forward assist issue, I basically don't use them except for making sure the bolt is locked up after press checking. It is possible to push onto the side of the bolt carrier and get the bolt to lock but not reliable, especially if it is dry, dirty, or extremely hot from firing. A1 uppers come in several variations like the C7 style that you see posted above that has the forward assist with shell deflector.

We still build on the C7 style upon request, but we seem to be building mostly on our ambidextrous flat top upper receiver that is combined with our A1 Carry Handle that is knobless.

Stay Safe & CY6,
Greg Sullivan "Sully"
Chief Instructor
http://www.SLR15.com
http://www.TheDefensiveEdge.com

 

[KriegHund]

Whoa...

Is 16" the minimum barrel length? I thought it was 18" (is is that only for shotguns, and can rifles have 16"??)

Oh, and unless your going with historical accuracys, just go wth whats cheaper (insofar as A1 uppers

 

[sully]

Federal rules for barrel length are 16" for Rifles and 18" for Shotguns.

CY6,
Greg Sullivan "Sully"
Chief Instructor
http://www.SLR15.com
http://www.TheDefensiveEdge.com

 

[KriegHund]

Hm, ok

 

[peabody]

fulton armory still sells the A1 slicksides.

im building a dissy with A1 stock, and a 1x9 pencil barrel, cutt back to 17.5, with old three prong flash hider.
triangular handguards..

love the rifle gas, so smooth n' soft. my neighbor bought a dissy from DPMS years ago, its got rifle gas, zero problem's.. lost count on the many hundreds of rounds shot through it.

im just going with a 17.5 barrel, and leave the gas port alone.
she'll be fine

peabody