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AndyRexia 08-15-2013 10:32 PM

New Build
 
Well I thought my last build would be just that, my last. We all know that's never the case and I started a new build this morning. I want to build a SBR. My intended uses will be for home defense and for work purposes, LEO. I have some questions though because I've never dealt with a short barrel AR. Any recommendations on barrel length? What kind of buffer should I be considering? Muzzle devices? Lastly, any recommendations on triggers? I ordered my lower, now I need to start the paper work. I know it's a long wait but I'm ok with that. It gives me plenty of time to shop around and buy quality parts and not settle for less because I want to hurry up and get it done. Normally I would know what to put on an AR but I don't know how the shorter barrel will effect the other components. Thanks in advice for any help.

KG7IL 08-15-2013 11:01 PM

I think a good start would be determining your desired barrel length.
Note that shorter will usually
* decrease the muzzle velocity
* increase the muzzle flash due to unburned powder.
* increase the muzzle report
* facilitate Close Quarter handling.
* Reduce Iron Sight sight radius
* Scare the ignorant.

I would guess that you are going 5.56/223
I currently have a 7" BHW Polygon in a pistol configuration. Carbine Spring and Buffer.

You most likely will not want to go that short. so take a look at barrels.
7.5 9.5 10.5 14.5 are available from Black Hole Weapons.
Similar lengths are available from other manufactures.

If you are going to suppress, then you will have some issues that I AM NOT familiar with. I use a muzzle brake, it adds a bit of dwell time as well as length. No issues with a 'can type' of brake like the SA Dragons Mouth.
Some may suggest an adjustable gas block. I didn't go that way.

Spend some time in the stickies and the Photo threads here on our favorite forum. Lot's of ideas there. http://AR15news.com has great news.

Both on the web and facebook.!

Now.... on barrel length and velocity.
I found http://www.ar15.com/archive/topic.html?b=3&f=118&t=511787 that has this chart.
http://i44.photobucket.com/albums/f4...8/velocity.jpg

AndyRexia 08-15-2013 11:40 PM

I was looking at a 10.5" 5.56 barrel from Noveske. I pretty much decided in that barrel unless someone comes up with a reason not to. I want a short barrel but not so short it should be a pistol.

I was also looking at can breaks. I was leaning towards the Flaming Pig. Any thoughts? Thanks a million for the reply.

AgentTikki 08-16-2013 02:10 AM

Before making any decisions, I'd strongly recommend looking at the ammo you intend to use as a LEO. Look at the typical velocities for the different lengths before choosing anything.

For example if I were to use m855 or m193, I would not go any shorter than 12". The minimum fragmentation velocities out of a 12" iirc are about 75 yards for those rounds. Not very long. But for cqb it'll do.

If it were for just a fun plinker ya go 7,8,9,10 but remember for short barrels these common milspec rounds do not even rach the necessary speeds to fragment and they will just pass through leaving a small 22 cal hole.

If you are usuing special defensive ammo, like soft points or any such expanding tip its still important to research the minimum velocities required for expansion.

And remeber eveyone except movie stars, leos and spec operators in cali hate you will all our hearts......please post lotsa pron!!!!

AndyRexia 08-16-2013 02:22 AM

Quote:

Originally Posted by AgentTikki
Before making any decisions, I'd strongly recommend looking at the ammo you intend to use as a LEO. Look at the typical velocities for the different lengths before choosing anything.

For example if I were to use m855 or m193, I would not go any shorter than 12". The minimum fragmentation velocities out of a 12" iirc are about 75 yards for those rounds. Not very long. But for cqb it'll do.

If it were for just a fun plinker ya go 7,8,9,10 but remember for short barrels these common milspec rounds do not even rach the necessary speeds to fragment and they will just pass through leaving a small 22 cal hole.

If you are usuing special defensive ammo, like soft points or any such expanding tip its still important to research the minimum velocities required for expansion.

And remeber eveyone except movie stars, leos and spec operators in cali hate you will all our hearts......please post lotsa pron!!!!

Thanks for the reply! I really doubt I would ever use it at those distances. I was thinking more along the lines of an active shooter in a school scenario, clearing buildings on search warrants, home defense, etc. So what ammo would you recommend? I have 0 experience with sbr's and want to learn. I've got plenty of time to do so. Any particular brand or grain? Could I get a 10.5" barrel and still use it in CQB effectively with the right ammo?

I'll post the pron as it comes in lol! My lower should be here in a few days so I'll keep the pics coming. Thanks again for the input.

Jpyle 08-16-2013 02:37 AM

Quote:

Originally Posted by AndyRexia (Post 1336760)
Thanks for the reply! I really doubt I would ever use it at those distances. I was thinking more along the lines of an active shooter in a school scenario, clearing buildings on search warrants, home defense, etc. So what ammo would you recommend? I have 0 experience with sbr's and want to learn. I've got plenty of time to do so. Any particular brand or grain? Could I get a 10.5" barrel and still use it in CQB effectively with the right ammo?

I'll post the pron as it comes in lol! My lower should be here in a few days so I'll keep the pics coming. Thanks again for the input.

Are you going to mount a suppressor? That will influence barrel length, ammo selections, buffer choice, etc.

purehavoc 08-16-2013 02:51 AM

I have a 7" and a 11" . The 11 is my favorite . The 7" is obnoxiously loud , the precussion for people around you other than directly behind u will make people gasp as its like someone punching you in the chest and the flash with a brake is enough to light a very large room with . They are both tons of fun so dont get me wrong . Love the shorty , but its more of a range toy .

AgentTikki 08-16-2013 04:40 AM

TAP is a great ammo, I have a few mags worth loaded up of it but its really expensive at .75 to $1 a round. I've only shot a couple hundred through my ar pistol to make sure it cycled and functioned perfectly. Its great in an sbr, but even better in a full 16" carbine. Also if you plan on using it indoors get a supressor, or at the very least a linear compensator.

ZeusEcho 08-16-2013 10:44 AM

Exciting build man! Gotta love the SBRs!!!

I'm building a 10.5" this weekend with a Rainier Arms Ultra-Match barrel. Was a 300BLK build but with the ammo shortage I decided to build a 5.56 upper as well so I can shoot it now since I got the stamp! :D

I got the Syrac Ordnance adjustable gas block (about $100 at Brownells) because I plan to run both suppressed (AAC-762-SDN6) and unsuppressed and figured I might need to do some tuning. It seems like a good adjustable block because the settings are locked by a pin so you can change settings and it will stay locked. Also you can change the setting from the front and they provide long tools for the job to get down inside most length rails.

I'll be using an AAC Brakoute muzzle device so I'm excited to see how that sounds/feels out of a 10.5" barrel.

As far as Trigger for the AR15 I'm a Timney fanboy. Just got a Geissele SSA and don't care for the feel of it as much as the Timneys but I need to give it some range time to really see how it is.

I'll be using this build for some defensive carbine competition so it will get some decent use.

Hopefully get to the range this weekend so I'll let you know what my experience is and post some pics. :)

Sgt_Skrb_25 08-16-2013 01:33 PM

2 Attachment(s)
Good choice to go with the 10" barrel. It makes it easier to balance out the cycling with a carbine gas system. If you go 7" inch it would take a little more precision to get her running right because of the pistol gas system. I am not a fan of the Noveske KX3 "Flaming Pig", Check into the PWS CQB. I don't think you want a foot long flame out the barrel, especially for duty. The PWS Is around the same price. I tried KX3, and didn't like it, PWS performed better. Here are some pics of the PWS.


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