10.5, 11.5, 12.5. . . . . . . .  .

Only want to do this once.  Balance, reliability, maneuverability, etc.

Not so much of a question of "best;" rather what advantages/disadvantages for each.

Thanks!

What caliber? .22, 9mm, 5.56, 300 Blackout?

Depending on your use/application, it may not make a difference.  I don't think you can go wrong with any of them as long as you get a quality barrel from a reputable manufacturer.

I have a Noveske 10.5" Mod0 SS Med Contour 5.56 in my SBR.  My understanding is that 10.5" is the minimum to maintain sufficient muzzle velocity to have decent terminal ballistics with 5.56.  It won't have a fierce of a muzzle blast as 7.5".  There are some mention of 10.5" not having enough dwell time for the action to cycle or more ammo sensitive.  My 10.5" has been flawless with range .223 and 5.56.  Which brings up why BCM only has 11.5" instead of the 10.5" is due to that "dwell" time.  BCM's 11.5" states that it is more forgiving to ammo because of the additional dwell time.  So with that in mind, having a 12.5" would mean even more dwell time.

Only thing I would change would have been to get a CHF chrome lined govt profile 10.5".  The Noveske Mod0 is a Medium contour SS barrel and is quite heavy (Adams Arms gas block does not help the weight situation, but makes it pleasant to shoot suppressed).

I am building a 300 BO pistol right now and planning to use an 8-8.5".  I want a compact AR pistol, but enough handguard space to just cover up to the shoulder of the barrel to hold on to.  I chose 300 BO because I can run subsonic ammo, without a suppressor, and still have the action cycle. Subsonic 5.56/.223 will not cycle an action.

My current favorite AR is my 16" midlength (standard CMV BCM 16" govt profile).  It feels lighter, muzzle wise, and overall very soft recoil impulse.

5.56 thanks.

Sionics, Noveske, BCM are on the radar for barrels and/or complete systems.

10.3 or 10.5.


My first pistol barrel was
11.5 because it was all
I could find at that time.
My second 5.56 is 10.5
and it's a perfect blend of
accuracy & compactness,
and still get standard iron
sight radius.

The 11.5 is not bad, but I
like the 10.5 a little better.

Later!

John

as was already mentioned, BCM went with an 11.5 barrel. that because the dwell time was 40% more than a 10.5 inch barrel which in a DI system made it much more reliable. a 12.5 barrel added a lot less of an advantage on the dwell time, while adding more weight and length, meaning less maneuverability.

i'd go with the  11.5 inch since it's the best balanced option.

http://www.ar15.com/forums/t_2_138/174764__Q__Why_BCM_chose_the_11_5_SBR_over_the_10_5_.html&page=3

I just built mine for fun. I went with 7.5 and I have a krink style brake like the Noveske. So you figure that puts you at 11". Anything longer and I'll just use my 14.5 middy. It runs like a champ, zero malfunctions. I have the phase 5 hex2c buffer kit which includes their spring, spikes st t2 buffer, pistol length gas system. It runs great, everything is perfect and it's a blast to shoot which is all I cared about. I'm not picky what my muzzle velocity is, It will do damage at 50 yards, I wouldn't want to be on the opposite end of it. It's accurate enough as well. I set a silhouette target at 50 yards and shot 80 rounds at the head, I missed 14 of em and not by very much. Not great but not too bad either, someone who is a better shot than I could get em all in their.





ETA: That is shooting from a standing position, no rest.



ETA: I am going to start another upper for it with an 8.5 barrel, I think that will be perfect. The muzzle blast can be pretty fierce on these little suckers, that is why I like the krink brakes, eventually I'll get the Noveske for the next upper.



 

My first pistol was a 7.5" Piston setup from Adams Arms.  I like it and still have it and shoot it frequently,

Currently building a 10.5" as my second to get improved muzzle velocity.  Using a KAK flash can or Noveske KX-5 depending on how it shakes out with reliability.

I like 10.5, barrel.

what's your overall length?... Buffer tube end to end of barrel (without muzzle device)?

Does 10.5" get you into 'firearm' vs. 'pistol' length?

I'm not a gambling man so unless the firearm is purely for range fun I'm going with an 11.5" bbl. Why?



Why BCM chose the 11.5" over the 10.5"

Colt's apparently making them with 10.3" barrels, for what that's worth.  And you'll hear lots of guys tell you that their 10.5" barrels have been fine.

~ 24.750 OAL.

Will an 11.5 with a Sig brace be too long to be considered a pistol????

There is no federal restriction as to OAL for a pistol.  For carry purposes some states limit either OAL and/or barrel length.  In AL for instance, if the barrel is > 12.5", it's not a pistol for carry purposes...


 

i posted the same link and i agree with you. 40% more dwell time for that 1 extra inch is just too significant of a gain for such a small gain on OAL, + the extra fps and wear n tear.  with an 11.5 inch and the sig brace i can still fit the gun sideways through a  standard door frame, 12.5 i'd be about 3/4 of an inch too big since the 11.5 is so snug already.

Yes I chose bcm 11.5 because of the better dwell time, increase in velocity and still extremely compact and handy. It is extremely accurate upper as well

What is this once you speak of?

Thanks. Much appreciated.

Let's look at this subjectively as well as quantitatively:

What was this application tested? A 5.56 would not be systemicaly the same as a 7.62x39 or a 300 blk. Or a number of other cartidges for that matter. Burn rate, pressure curve & expansion ratio all play a part in this scenario of ideal dwell time & velocity gain.

Let's keep that in mind for these broad generalizing ideals.

I couldn't make up my mind so I built both an 10.5" and 11.5". For all the reasons mentioned, 11.5" to me is the better "short" size. Both have been 100% reliable(approx 1.5k combined thru them) to date fwiw.

7.5 makes a great trunk gun. 10.5 is like having a sbr

I am building my first pistol (have the lower completed) and trying to decide on an upper receiver. I am going with 5.56 as .300bo does not interest me.

I have handled a 7.5" and 10.5" pistol and liked the feel of both of them. However, I want something shorter than the 10.5" barrel without getting the excessive blast from the 7.5". I believe a 9" barrel would be ideal but would like others opinions.

My thinking is the 9" barrel is a nice compromise in overall length and noise. Can use a carbine length system also. You might say it is only 1.5" but that makes a difference running through a house or getting out of a truck, and the extra 1.5" will be a bit more accurate compared to the 7.5".
Thoughts?

I have found a couple places online with this length barrel, but due to price I am considering buying a longer barrel and having it cut down and threaded.

Wow, very nice.  I especially like the version with the carry handle .

Thank you sir.