Why don't I see the 12.5" AR SBRs anymore? - Page 2

Armory » Short Barreled Rifles (SBR)

[ARCHIVED THREAD] - Why don't I see the 12.5" AR SBRs anymore? (Page 2 of 2)

Posted: 1/26/2017 6:07:09 PM EDT

[#1]

Quote History

Quoted:

I'm
On our mk18s, for my unit, we were averaging between 3500 to 5000 before a bolt failure. Then crane tried to get us to use the one piece gas rings and that resulted in a bunch of FTF and FTE. By the time I got out, it still wasn't resolved (2014).

View Quote View All Quotes

View All Quotes

Quote History

Quoted:

Quoted:

So how many rounds through my 10.5" until my bolt fails?

What about my 16"?

I'm
On our mk18s, for my unit, we were averaging between 3500 to 5000 before a bolt failure. Then crane tried to get us to use the one piece gas rings and that resulted in a bunch of FTF and FTE. By the time I got out, it still wasn't resolved (2014).

What type of bolt failures?

Posted: 1/26/2017 6:12:10 PM EDT

[#2]

Quote History

Quoted:

What type of bolt failures?

View Quote

3 different bolts sheared lugs, and one cracked in half at the cam pin.

Posted: 1/26/2017 7:17:52 PM EDT

[#3]

Quote History

Quoted:

3 different bolts sheared lugs, and one cracked in half at the cam pin.

View Quote

I've had good luck with my CQBR, has around 15k on the original bolt (BCM bolt.) Just my one singular experience with a semi-auto rifle, I do keep a spare bolt and bolt parts in the case with the rifle since i'm expecting that bolt won't last forever (or even much longer.)

Posted: 2/1/2017 9:59:30 PM EDT

[#4]

The rifle I use to KILL things is a 12.5" 6.8spc. I do own a 10.5" 5.56 SBR as well, but haven't had the success with large hogs that the 12.5" offers.

Posted: 2/2/2017 5:47:47 PM EDT

[#5]

I built that 12" upper when Larue had a barrel sale. Look at how close the length is to my Tobr 14.5" with the freakishly long SF Brake. They are called short barrel rifles not kinda short barrel rifles.

My MK18 upper has been shot over 8,000 times and still original. I haven't shot the 12" since I tested it and dialed in the irons because it feels like i'm carrying my Tobr, it just doesn't feel right after using my 10.3" for so many years.

I've lived and learned and IMO if I had limited disposable income I'd go with a 14.5" P/W over buying a stamp for a 12.5".

Posted: 2/3/2017 9:40:44 AM EDT

[#6]

I love the 12.5" length. I have one in 5.56 and one in 300BLK

12.5" Noveske 5.56 w/ Form 1 Reflex Suppressor

12.5" Noveske 300BLK w/ Gemtech Quicksand

Posted: 2/3/2017 10:54:54 AM EDT

[#7]

My current project consist of a 12.5 inch barrel in .300 blackout. I only chose this length because of the ALG handguard I received for Christmas. The weight isn't to bad though and it is going to be my hunting rig.

Posted: 2/3/2017 11:19:09 AM EDT

[#8]

Memory fails me at the moment but IIRC that 11.5" gives the 5.56 NATO fragmentation out to 125 meters were the 10.5" loses enough velocity that it bullet at the muzzle is below fragmentation level. Sure that @Zhukov will be along in a short to correct this.

The 'sweet spot' (aka point of diminishing returns) on the curve of MV vs. barrel length for the 6.8 SPC & 6.5 Grendel is 12.5". Again, IIRC that a bullet from the 6.5G is still supersonic at 500 meters out of a 12.5" barrel while the 6.8 SPC will give fragmentation to 200 meters with a 12.5" barrel.

Posted: 2/3/2017 2:47:52 PM EDT

[#9]

Mine is still chugging along. Getting close to 8K though it.

Posted: 2/3/2017 2:58:15 PM EDT

[#10]

For me personally, if it's a 5.56 I'd rather have something a little shorter. If I want it to be longer than 11.5" I'll just go 14.5" and pin it.

That doesn't make it right for you, but it's right for me.

Posted: 2/4/2017 10:32:28 PM EDT

[#11]

Just finished my 12.5 build with a ballistic advantage barrel.

Posted: 2/6/2017 5:36:12 PM EDT

[#12]

Well I'm waiting on parts for my 12.5 inch SBR build in 5.56 and 6.5 grendel. So I'll be back.

Posted: 2/7/2017 12:22:46 PM EDT

[#13]

My centurion arms 12.5 upper is my my favorite

Attached File

Posted: 2/8/2017 4:08:05 PM EDT

[#14]

i'm going to rebarrel my 10.5" with a 12.5" and run a form 1 reflex can.

Posted: 2/8/2017 4:30:44 PM EDT

[#15]

Quote History

Quoted:
i'm going to rebarrel my 10.5" with a 12.5" and run a form 1 reflex can.

View Quote

Seems like a valid reason to go with 12.5"

Posted: 2/8/2017 6:21:56 PM EDT

[#16]

Quote History

Quoted:

Seems like a valid reason to go with 12.5"

View Quote View All Quotes

View All Quotes

Quote History

Quoted:

Quoted:
i'm going to rebarrel my 10.5" with a 12.5" and run a form 1 reflex can.

Seems like a valid reason to go with 12.5"

i've got a 9.6" tube so i'll have plenty of room for baffles and the section over the barrel.

Posted: 2/15/2017 9:22:20 AM EDT

[#17]

I'm waiting on a Form 1 back for my 12.5" BCM Kino now.

12.5 ain't dead.

Posted: 2/18/2017 9:32:02 PM EDT

[#18]

Is 12.75 close enough? I love this gun. However, at the time PWS only offered the Mk110 and Mk112. If I could go back I'd have waited for the Mk111.

Posted: 2/18/2017 11:03:44 PM EDT

[#19]

8.5 for 300bo.
11.5 for 556
12.5 for 6.5 and 6.8

Posted: 2/18/2017 11:18:59 PM EDT

[#20]

12" is a great length

Posted: 2/19/2017 9:39:08 PM EDT

[#21]

Suppressed 11.5 FTW (bottom gun)

Posted: 2/22/2017 6:36:19 PM EDT

[#22]

Colt 901 16SE 12.5"

With Gemtech HVT-QM

Posted: 2/23/2017 6:27:10 PM EDT

[#23]

Here's mine.

[ARCHIVED THREAD] - Why don't I see the 12.5" AR SBRs anymore? (Page 2 of 2)

Armory » Short Barreled Rifles (SBR)

Win a FREE Membership!

Sign up for the ARFCOM weekly newsletter and be entered to win a free ARFCOM membership. One new winner* is announced every week!

You will receive an email every Friday morning featuring the latest chatter from the hottest topics, breaking news surrounding legislation, as well as exclusive deals only available to ARFCOM email subscribers.

Warning

Confirm Action

About AR15.COM

Stay Connected

Newsletter

Contact Us