I'm tossing around the idea of building an AR like this:

20" Gov't profile bbl, cut to 18", in dissipator configuration w/full length gas tube, A2 FS and milled off bayonet lug.

A2 upper receiver.

A1 length buttstock made from A2 materials and with A2 buttplate.


What do you think of this configuration? I figure it will only be about 2" longer than a 16" LW carbine with the stock extended, and about 1.5lb heavier.

It would look something like this:
[img]http://albums.photopoint.com/j/View?u=1191620&a=12698392&p=48744451[/img]
Nothing radical, just a slightly faster handling package than the original.

You dont want to go cutting the barrel when the gas hole is already cut into the barrel.  Some genius on the old board took a 20" barrel and cut it down to dissapator size.  Of course, since there wasnt any space between the gas block and the muzzle, the gas impulse to the carrier was not enough to cycle the gun.  Net result: One ruined barrel.  Have a smith start with a barrel blank and cut the hole at the right distance from the muzzle.  

Why not just buy a light weight barrel and keep the full length?  With .223, velocity is life and cutting the barrel 2" will drop your velocity something like 200 fps.

Kharn

If you are looking for a light weight Dissipator style weapon, you have a couple of options.  You can get a standard Dissipator upper and have the barrel turned down by Kurt at Kurts Kustom Firearms.  I also seem to remember that Bushmaster is producing the Dissipator barrel in a light weight version now. There are a variety of muzzle brakes available if your recever is post-ban.  If you have a pre-ban then the A2 flash supressor is certainly an option.

It'll still beat the hell out of the MV of an M4, and a few people around here seem to think that is a viable combat weapon. [;)]

Keeping the full length gas tube is one of the main goals of this project. That rules out all the BM dissipator uppers. It will be built on one of my pre-ban Colt receivers, so the A2 FS is a must, the only reason I'm going to trim the bayonet lug is because it won't be of any use with an 18" barrel.

Why ruin a nice gun?

Because a 20" balances too far to the front, more like a target rifle than a fast handling game gun, and the A2 stock is too long to shoot well from prone position, or when wearing an LBV, unless you are a gorilla.

Have you handled the ArmaLite M15A4™ Carbine?   I think it would fit the bill for handiness. Besides I wear a 36" sleeve,a 32" inseam and have a 56" chest.  I have to get back to my tree now.

I've just sold a Bushie M4gery, and 2 Colt 6520s, I no longer get all hot and bothered over the shorties. I want a weapon with improved handling qualities that doesn't give up much of the practical accuracy or effective range of the full-sized rifle.

I've seen guys cut the barrel back and bore out the gas port slightly. They run ok if you do it right. I don't know how much you have to open up the port. I think Fulton Armory does it this way.
It looked kinda like this...
[img]http://wsphotofews.excite.com/024/sy/YF/7b/Q526793.jpg[/img]

Actually, the Fulton Armory Dissipator upper is what got the wheels turning in my mind. I think the 1/12 twist barrel with NM sights on their Millenial Dissipator upper may be one of the most moronic ideas of all time, never mind how spendy they are!

I've already done it.  It's a great idea.  I went without a muzzle device, since I put it on a post-ban lower.  I also used an A2 length stock, because that's what I had laying around.  I cut the barrel back to 17.75" actually.  It leaves plenty of barrel in front of the gas tube to ensure functioning.  The A2 Govt barrel, with a slightly shorter front end balances great, and handles much better.  Go do it, you'll like it.  I can't post a pic as my system quit working and I'm using the laptop right now.

Ross

Thanks Ross! Glad to know I'm not the only one who thought this would be an improvement. You don't happen to have any chrono numbers with the 18" barrel do you?

No.  I have a chrony, but I haven't had a chance to use it yet.  It just came in the mail a couple weeks ago.  Like you said, if 14.5" is good enough, then 18" will probably suffice as well.  If I get it clocked, I'll post it.

Ross

I have no problems with the handling qualities of a A2 20" HB. I use a HK G41 at work and the A2 seems better after 12 years of the G41.
I do have a AR carbine for the wife or "close" work.

Join the Guard and get your own M16A2.

M4 with fixed stock fills that place

Nope, I don't want the short sight radius and carbine gas system. Been there, done that.

I here you! But wont you be making a "halfbred" stuck in the middel, dont belong to one side or the other? not really good for any one thing?

I really can't see anything major I'd be giving up with this rifle. It seems like a configuration that could do everything the full-sized rifle can do, and at only around 2.5" longer than an M4 with the stock extended, work well in tight quarters.

Yeah, I'm biased, but why don't you share your insights on the uselessness of the M4 with our special forces, I'm sure they'ld like to know that the weapons they carry are no good.

Don't get your panties in a wad M4, I never said the M4 was no good. I was pointing out the fact that if the MV from a 14.5" barrel is good enough, then how can an 18" barrel have an unacceptable MV?

If you are going to go this route..might I suggest a  1 in 9 twist -Bushy- GI profile- chrome lined 20" have it cut down to 18"install a phantom flash hider..if you have a large pivot hole lower..Id go with the new Les Baer flat top upper that have the large pivot hole...go with flip up front and rear sights and put some decent glass on it..the ACOG for example...just a thought

Why not just buy an Armalite M15A2 Carbine. You will get the longer sight radius than a standard carbine, longer gas system. Just put an A1 Stock on it.

NO SLACK!

I want to stick with the 1/7 twist so that M856 tracer can be used. The Phantom FH is a definite possibility, I'm still mulling over that one. I want the fixed A2 carry handle upper to fall back on, but I'll probably mount a compact ACOG as the primary sight. I haven't decided yet.

Nice rifle, but [b]NO EVIL FEATURES ALLOWED![/b] I'll be having none of that, thank you. [;)]

You have a preban and say you want evil features. You mean like the evil full length stock and the evil ground off bayonet lug and evil non-bayo compatible barrel length??????

What's wrong with an M4?? Stock is light and adjusts for A1 length, body armor, etc. 14.5" barrel will give you ability to actually USE the evil bayo feature. And a Phantom works 100% better than an A2.

As far as the sight radius goes, if you want it for the "ultimate all-around combat AR" (AKA CQB) weapon, what the hell do you need full sight radius for? Accuracy? At what "combat" range??

My recommendation is to use your preban and build an M4. You will save money by not having to pay a gunsmith for anything and there is a much less chance of having something screwed up. You will save weight with the stock and the barrel, and nomatter what carbine problems you had before, a quality carbine should not screw up any more than a full length gas system.

My baby, over 2000 rounds with not a single gas related hic-up, mostly only fired full auto/rapid fire.
[img]http://wsphotofews.excite.com/033/vS/oV/Rv/Q391168.jpg[/img]

Relax M4, I don't think there is anything wrong with the M4, they just dont do it for me anymore. I just sold a preban BM M4 and 2 preban 6520s. I have had no problems with my carbines in the past, but I feel the full length gas tube is the most reliable configuration possible.

Obviously I'm concerned with more than just CQB handling or the M4 would be just what the doctor ordered. I think "ultimate all-around combat AR" implies ranges from 0-500m+ and I'll take every bit of that extra sight radius if shooting anywhere near the maximum effective range of the M855 round with iron sights.

The only preban feature I'm concerned with is the flash hider, the bayonet lug comes off for the weight savings, and the A1 fixed stock will take more abuse than a collapsible stock any day of the week.

I am also an individual. I like my tools to have a bit of style or be unique as well as functional and dependable, no more cookie-cutter M4geries or AR-15A2s for me, I'm trying to think a little out of the box here.

Cost was the major consideration for me in building mine.  I already had all the parts laying around, except a reciever.  I bought a post-ban lower for $100 and that was it.  So an AR carbine for $100.  Even if you add the cost of the parts that were left-overs from other projects, it wound up costing under $450.  I'd have a hard time replicating a pre-ban M4 for that price.

I personally don't like telestocks.  I don't find them comfortble to use.  I don't need to adjust for a flak vest.  I don't find the collapsing feature of the M4 to be all that great when compared to a conventional folding stock like on a K2, AR180, ParaFAL.  I've owned several CAR-15 types, and I've always gotten rid of them because I never liked the stock.  I see no reason to spend the kind of money an M4 would take, just to "keep up with the Jones" and have a gun I don't like.  I don't like Glocks either.  Carried one, but eventually got rid of them because I just didn't like them.  The CAR-15 variants work for some, just not for me.

Since I wasn't going to use a telestock, I didn't see the reason to go with an upper that was going to have short handguards or short sight radius.  When you add the extra length of the Phantom FS, mine is only about 1.5" longer than an M4.  Yet at 2.25" shorter than an A2 the handling qualities are great.  Do I need the longer sight radius?  Certainly not.  Do you need 600m sights on the M4?  Probably not, but most people get them that way.  I've given serious consideration to using an A1 type upper, but that's adding cost to a low cost project.

Since I used a post-ban, I didn't need the bayonet lug anyway.  In fact the barrel I used was a leftover Colt without the lug anyway (I suppose another reason to build it post-ban).  

Before I built the gun, I was not really convinced that it made much sense either.  I had all the parts laying around, and wanted to build something, so I figured I'd give it a try.  It came out great, and I have found the gun to be quite nice.  I found it more comfortable and more enjoyable to shoot than an M4 for me.  I found it MUCH less expensive than an M4.  I think 700PSS will like his gun very much if he builds it his way.  I recommend he proceed with his plan [:)]

Ross

Okay, here is the $64,000 question: who makes an A1 stock out of the same material as the current A2 stock? I don't want to use one of the old grey fiberglass A1s if I can help it.

700pss - colt made them for blue label carbines - they can be id'd by the cs (custom shop) logo on the fron right of the stock.  i have one - sorry not for sale.  i'm sure you can hunt one down - check with dealers who stock colt stuff

steve
ps - email me so you can mail me the check for $64k

Thanks for the info steve, the (rubber) check is in the mail! [;)]

Why the 18" barrel? And why not the BM Dissipator?

The BM Diss is going to be more reliable over a wide range of
ammunition and environmental conditions that a “chopped” 20"

BM Dissipator has the shorty gas tube, I want the full length tube. The 18" barrel would have better balance and be more handy than the 20" without sacrificing as much velocity as a 16" barrel.

PSS-
Have you found the perfect woman yet?  
I've been looking at the posts, and you're shopping for the rifle that doesn't exist---yet.
I'm curious as to how you'll put this one together. I'm rooting for you to prevail, because I rather like the underdog approach myself.  This will be a great setup when you find all the parts in all the right places.
Good Luck.  You can do it.  It's fun getting what you want!

I have the Pre-Ban Dissipator with ALL the bad-boy features in its standard configuration.  I just got the V-MATCH 24 upper for it, and, thanks to the guys here at the Forum, found out the Telestock wouldn't work with the longer gas-tube...so, I had to get the new "TeleStyle" buttstock for it to work correctly, and it does.  The only real "sacrifice" I had to make was not having the "Tele" in the buttstock.  Oh, well.  If it weren't for the comments on the Forum, I could've made a big mistake and not known what I'd done wrong.
The Dissipator is my favorite Combat Carbine.  The V-MATCH upper allows for more accurate target shooting until I spring for the new Post-Ban Bushmaster Lower, thereby giving me 2 Bushmasters to work with.
That's my story.

No, but I've found several with a feature or two that I like. I'm trying to figure out how to assemble them into the "ultimate all-around woman". [:D]

Thanks for the encouraging words about my pet rifle project! It may take a few months (finding that A1 CS stock will probably be the death of me), but I'm going to get all the parts together and do this thing. I'll probably send the upper to Kurt and have him cut the barrel and deal with the gas port modifications if necessary.

You want the ultimate combat rifle?  You already have it.  It amazes me the number of folks that think they can improve on what millions of dollars worth of R&D, and the combined wisdom of hundreds of experts come up with.  The standard 20" setup has been found to be the ultimate for what it is designed for.  Now we have a host of other barrel lengths on the market, but those have all been designed for a specialized niche.  If your needs fit into that niche, you need a different ultimate combat rifle.  

Ever consider just getting a 20" barrel spun down to a light weight profile?  You'd have a lot less problems getting that done then getting someone to mess with the gas system.  Whats wrong with the carbine gas system anyway?

Kharn

I have an SP-1 that had a 16" BARREL (C.A.R.15)My final choice was to go with the 11.5" barrel with the 5.5" flash hider. It is compact and quick handling.