If you only had on rifle to use, would 12.5" work? I have a 16" AR. Thinking of cutting my 14.5". Will I really miss that two inches? If I ever have to use this gun Seriously believe it will be for home defense.

Go shorter. I've had 10.3 and 10.5 and currently use a 11.5" for HD and I'm building a 556 and 762x39 12.5" right now
Plenty of YouTube vids of guys ringing steel at 600m with a 12.5" and I believe Kyle Defor posted a pic of his 11.5" and the caption said "500m all day long"
ETA: Barnes 62g TSX

Posted Via AR15.Com Mobile

my go to rifle is a 11.5 . it shoots just as good as my 16" . The only thing that differs is the velocity.

It depends. If I were looking for a true do everything, and did intend to stretch it beyond 350 yards, then I'd probably opt for the 12.5.

Reality is, I see little reason why I'd truly need to stretch it beyond 350 yards, so I find an 11.5 to be the sweet spot for me.

I also have a couple 10.3s, and for most, even those would cover any and everything you'd ever actually need out of your rifle.

There's not really a wrong answer for an SBR barrel length. It just depends on what all you're looking to do.

My BCM Kino is my favorite and most used rifle. I find it to be pretty much perfect for me.

you still live in CA? 12.5" barrels are a no-no.

But other than that, with the ammo current;y available, a 10" will do everything you will most likely ever ask of it. target shoot out to 500-600 as well as have good terminal ballistics out to 250.

Build a second upper, ideally something more suited to a short barrel like the 300 Blackout.  You can run a 9" barrel and get a full powder burn, unlike the 5.56 which needs twice that (about 18.5") to do the same thing.  That means far less flash (for night vision as most dont have NVGs at home) and far less BANG (it will still suck indoors but the suckage will be reduced), out of a still smaller package (my pistol is about 25" long).  Additionally it gives you bigger bullets making bigger holes in your target, all without the need for special magazines or bolts.

Math works out to about 1400ft/lbs of energy for the BO.  A .44 Magnum averages around 1000 ft/lbs.  From a 12.5" a 5.56 is managing 1100ft/lbs of energy but with a much smaller wound cavity compare to either of the others.  YMMV but I'll take an expanding .308 bullet over a .22 for HD any day.


Here's a nice comparison...  
http://i.imgur.com/FHHJ4.jpg

http://www.thetruthaboutguns.com/2013/07/jim-barrett/comparing-sbr-calibers-5-56-223-versus-300-blk/


The only down side at all is the ammo is a bit more expensive (I'm paying about $.60/round at Freedom), but if you reload the extra cost goes away since it uses 5.56/.223 cases as the parent case anyway.  I finally found a way to not send my stepped-on split neck-cases to the junk brass box.  Instead they get cut down, reshaped, and continue life as a BO case.

My go to rifle is a 11.5" with a suppressor pending (although I have a 9" 300blk with a Suppressor pending also) and my 3gun rifle is a 12.5".  A 16" for home defense is really to long to sweep through doorways with.  I would definitely SBR your primary lower if that is allowed wherever you are.  You have a real possibility of  hearing loss if your firing a unsuppressed AR in the house, a shotgun or handgun may be a better choice for actual home defense.

One thing I would add is that an 11.5" SBR would usually benefit from an adjustable gas block to make it nice and smooth.

12.5 should work great for you. I personally went shorter, to a 10.3.

AR-Ryan has a great point, the theoretical problems at long ranges are, IMO, overstated. If you're shooting that far for fun, that's one thing. However, I can't envision a reasonable scenario where a civilian is going to need to shoot in self defense that far, particularly with a short barreled carbine. At least not without going to jail, in normal times, or making yourself into a target, if you're imagining post-disaster stuff.  I tend to look at my personal ARs as PDWs, which is to say, means to extricate myself/others from situations, rather than intentionally involving myself in them, so your mileage may vary.

Summarizing my wordiness, it should do everything you need, just fine.

If it is over gassed, sure.  My 10.3 DD is over gassed, and will benefit from the adj gas block.  My 11.5 is nearly perfect, and is smooth with only an H buffer.  It is also a LW, so if it were gassed hot, I would feel it.  Some just have larger ports.

To the OP, I would not have a problem only having a 12.5, I like the length.  Tough decision between 11.5 and 12.5, for sure

It will actually be on pistol lower here in Cali.(Out of state it will SBR & have a can.) I also have a 12.5'' in 300blk. THX for info. guys.

My only AR is an 11.5". I wouldn't have a problem having a12.5" as my only AR either.

My BCM Kino is my choice, I like the 12.5

The 12.5 I own will work just fine.

Surefire Mini on the 11.5''?  God damn that is glorious.

I like the 12.5" in 6.8:



       
 

Man, I so wish my state would allow me to own an SBS!

Switched up from a PWS 7.5" diablo, to the 12.5" PWS... best decision I made.. Its my new "end of the world" rifle...

Great looking, well thought out collection there.  I went with a full size can for my 11.5", but damn that looks awesome.

If you are looking to put a can on it, just consider the muzzle pressure between even a 10.5 and 12.5 is significant....different cans are rated for different min lengths.  Just one more thing to check before you make a final decision.  I have a 10.5 and a 12.5 and also notice a bit of difference in the blast when shooting unsurpassed.

Here is one thing I do know...loosing that 4-5 inches does make the weapon a LOT handier to bring on target and maneuver with....

ZY

Thx for info guys! Really like the pix! Did any of you open up our gas hole any? What size gas hole are you running?

Yeah, it's a SF Mini.

I could definitely make do with a 12.5" as my only AR.  It's about the perfect length for an all around jack of all trades rifle.

12.5 and 16" are my favorite lengths and yes, if I could only have one it would be a 12.5. Without hesitation.

12.5 is perfect for an unsuppressed SBR.

I have a 12.5.  It is my favorite out of all my sbrs.  

ETA: here is a pic.  I use a mini 4 on it.  this is my go to hog hunting gun.