Looking to build a 7 inch AR.... Pics for ideas please.

[Miami_JBT]

Looking to build a 7 inch AR-15.

Iether I'm going to go with a Primary Weapon System Diablo upper or I'll go the cheap route and build a DI 7 inch with a DPMS Kitty Kat Barrel.

This is my idea if I go the DI route.

A3 Spike's Upper
DPMS 7 inch Kitty Kat Barrel
Primary Weapon Systems CQB Comp flash hider
Midwest Industries rail for 7 inch carbine

I'd rather have a standard A-post front sight. So can I use Midwest's rail with the DPMS barrel?

Basically something like this...

Some pics for ideas also please....

Thanks

 

[kwelz]

Make sure you go ahead and get your forms turned in. From what I hear the ATF is pretty backlogged on getting Class 3 stuff approved.

 

[jpwilly]

The muzzle blast and effectiveness of the 223 must really shine in that short of a bbl.

Do you load with pistol powder at some point?

 

[MarineOne]

I'm thinking I could open a tanning salon with the muzzle blast from that thing.






Kris

 

[TexasRifleman]

If you build one you should really consider suppressed.

If you just can't do that, then you need the Flaming Pig. Don't even look at any other flash suppressor.
You put any other flash suppressor on that thing and you will hate it. People you shoot with will hate it even more

I put one on my 11" AR and it truly changed the usability of the rifle.

http://noveskerifleworks.com/cgi-bin/imcart/display.cgi?item_id=kx3556p&cat=11&page=1&search=&since=&status=

ETA: I do agree that 7 is just too short for anything except a toy. 11" is to me the shortest usable length.

 

[CleverNickname]

If you want to suppress the gun, consider that many suppressor manufacturers will void the warranty if their 5.56mm suppressor is used on a <10.5" barrel. Adding a few inches to the barrel length doesn't really decrease the operator's ability in handling the gun. Also if you plan on shooting anything other than paper, those extra few inches on the barrel will help get the bullet speed up to something useful.

 

[Duelist]

build a piston-driven gun. the blast from a DI system will really cook your parts. Adams Arms has a kit for it.

 

[TeamRush]

Take the front sight off, thread the gas port, and screw in a 'Set Screw'...
Drill out the set screw a little at a time to get the amount of gas to operate the bolt without cooking parts or causing recoil related extraction or feed problems.

When I first got mine up and running, I tried the 'Piggy Tail' gas tube... Around $100 to get it here, and it was nothing but a 20" barrel gas tube someone had annealed and wound around the barrel about three times.

Worked OK for a while, but was impossible to clean correctly, and the SBR was a PAIN to keep cycling with stock/available ammo without special loading...

The set screw cost me 50¢, took all of about 30 minutes to install, and I only had to take it off for resizing once to make it right...
Been in there for three years now, swallows all kinds of ammo with no problems!



Since then, I've used the same idea to cut back on the gas from my 'Hot' prairie dog/ground hog/coyote hunting loads so the AR cycles like it's supposed to, and it works fine with all the AR rifles.

DO NOT try and use an open "Bird Cage" type flash suppressor on the front!
You WILL loose hair off your knuckles!
I use the A2 type flash suppressor, with the sold bottom on it angled so it protects my hand some!

And DITTO with the paperwork to the BATFE!
I've been waiting 4 months for my newest toy, and they say they are at LEAST 6 months behind right now!

 

[Big44mag]

7" with a KX3 inside a PRI rail.

 

[Exposure]

Here's mine-

Flat top upper, 7.5" barrel, YHM 4 rail handguard, YHM Phantom flash hider, all attached to my registered full auto lower.






The muzzle blast is quite impressive, I am not a huge fan of standing right the thing when someone else is running it, but it is much more tolerable then my Barrett. As far as the naysayers go, it is very accurate out to at least 100 yards. It also will still move a 62 grain slug fast enough to detonate Tannerite at 100 yards, so still in excess of 2000 FPS. I absolutely LOVE this thing.

Until recently I had been running it with a carbine spring and buffer but have just started to get light primer strikes in full auto which I am pretty sure is gas port erosion. That Beta Mag in the first pic has had more than one emptying by a single pull of the trigger. It sure is impressive to watch and do, but it is murder on gas ports and gas tubes! If done at the end of the day when the sun is setting the gas tube is glowing bright orange by about the 50 round mark! Lots of fun.

I have switched back to an AAC rate reducing spring and buffer and she once again runs like a top with no more light primer strikes, just a bit slower. Here is a short video, check out that fireball!!!




Good luck with your build, these things are a hoot!

 

[Bill_Rights]

Good luck on getting muzzle velocity up and controlling muzzle flash/blast if you use standard NATO5.56mm (.223) ammo in that 7" barrel. There is a current thread (Knight Arms Co PDW) in which one of the main points is that a respected manufacturer had to take some pretty extreme steps to solve these problems....

 

[dscottw88]

ATF is pretty backlogged on getting Class 3 stuff approved.

Yeah, I'm still waiting for forms I requested back February.

Are your guys' AR's running smoothly? I Hear that the 7" models are really hard to get working. This is why I want to build a 10.5" SBR.

 

[TeamRush]

I've built a couple for other people, and the 7" are REAL hard to get running with 'Factory' ammo.

Use the gas restriction (Set screw drilled out) in the front gas block, and you can use a direct (short) tube,
But you have ZERO chance of getting full strength .223 ammo to work without gas restriction.

http://www.brownells.com/aspx/ns/store/ProductDetail.aspx?p=1591&title=AR-15/M16 PIGTAIL GAS TUBE

These 'Pig Tail' gas tubes work, but they are EXPENSIVE and they can be REALLY HARD to tune with super short barrels.

Just drilling/tapping the gas block and inserting a gas restriction.... Then drilling it out to the size you need is about the best way to go about it that I've found.

9"/10" barrels are AMAZINGLY easier get running than the shorter ones...
----------------------------------

I have one, and have had several down through the years,
And I can safely say it takes a special kind of STUPID to own a rifle with a 7", 8", 9", 10" barrel!

Having done this for the past 30 years or so,
I can tell you, there are better calibers for AR PDW/SBR than the 5.56 or .223 Rem rounds!

I have a .45 ACP top end that you simply DO NOT want to be around when it cycles!
Anything down range is TOAST!
Mags are cheap in both 9mm and .45 ACP versions, and you don't have gas problems since they are blow-back systems...
And with blow-back bolts, you can use NO STOCK or FOLDING STOCKS with ease.

I even saw a .380 version of an AR/SBR and I have to admit,
I though of it as a toy until I spent an hour with it at the range!
It was pretty effective, especially in the suppressed versions!
-----------------------

If you don't like the recoil, consider a P-90 for PDW/SBR.
They work GREAT! (and that's coming from a long time AR man!)
In my opinion,
(and opinions are like buttholes, everyone has one and they all stink!)
The P-90 is the BEST PDW/SBR rifle ever made to this point in time!