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9/22/2017 12:11:25 AM
Posted: 2/24/2006 12:39:44 AM EDT
What is the effectivity of an 11.5 barreled AR with a 1/9 twist? And when does this barrel length useful? Is it still effective enough for defensive use? or will there be minimal chances of fragmentation? and what ammo is ideal in this lenth and twist?thanks
Link Posted: 2/24/2006 12:56:11 AM EDT
[Last Edit: 2/24/2006 12:58:52 AM EDT by Boom_Stick]
This is the complete guide for 5.56 ammo and selection for twist, length and performance.

It'll definitely bring down the frag range. To answer your question quickly, I'd use the newest heavy balistic tip loads for an 11" barrel. However the the link above will give you the best info.
Link Posted: 2/24/2006 1:11:18 AM EDT
If it is an actual 11.5 bbl, it has a use, mostly CQB work.
If it is an 11.5 bbl with a 4.5 in flash hider attached, forget it.
Link Posted: 2/24/2006 2:16:05 AM EDT

Originally Posted By thedoctors308:
If it is an actual 11.5 bbl, it has a use, mostly CQB work.
If it is an 11.5 bbl with a 4.5 in flash hider attached, forget it.




thedoctor is right. This set-up is used at distances that almost negate the terminal ballistics factor all together.

In many/most cases, we are talking distance inside 50 feet. At 50ft, the blast alone is almost enough, especially out of a short barreled 5.56/.223 AR.

Imagine breeching a room, pulling up on a perp sitting on a couch 10 ft. away- who decides to reach for his gun.

The bullet you shoot him with will have made 13 revolutions when it blows a hole in him.

With a 1/7 barrel, it's made 17 turns.

Not a big deal.


For those reports of shots or even kills out past 100 (or maybe 200) yards, 1/9 is likely not used

It is probably 1/7 guns doing that damage - and for that reason, it would be my first choice.




Link Posted: 2/24/2006 4:27:24 AM EDT
Sorry to hijack but... I just bought a Colt 6921 14.5" SBR. I have been thinking of getting an 11.5" upper (probably one of the new Colt gas pistons, when they come out) for home defense use. Before this thought, I was planning on using the 14.5" for home defense with Hornady 75gr. TAP.

First, would the 11.5" be a good move, or should I just stick with the 14.5"? Second, what are some advantages and disadvantages of the 11.5" barrel? And finally, would the 75gr TAP round still be one of the top tier zombie rounds in the 11.5" config. or should I switch to something heavier or something lighter?
Link Posted: 2/24/2006 4:29:01 AM EDT

Originally Posted By sunga_sy:
What is the effectivity of an 11.5 barreled AR with a 1/9 twist?



Three rounds, center mass, move on.

Link Posted: 2/24/2006 4:37:24 AM EDT
If you choose and 11.5 then go with a 1/7 twist barrel and use 75 or 77 grain bullets. The fragmentation range will be down to somewhere around 50 yards I think.

Much better choice to go with a longer barrel unless you have a need for the extra short barrel such a CQB work.
Link Posted: 2/24/2006 4:39:33 AM EDT
I always thought of the sole purpose of a 11.5" barrel was to still have a compact carbine when you stick a 5.5" sound suppressor on it. I will never understand the point of a 11.5" barrel and a 5.5" flash hider.
Link Posted: 2/24/2006 4:39:37 AM EDT
Crap I just noticed you said 1/9 twist. If that is the case try some 75 grain loads and see if your barrel will stabilize them. If so the go with the 75's if not go with some 68 grain loads.
Link Posted: 2/24/2006 4:40:22 AM EDT
[Last Edit: 2/24/2006 4:42:24 AM EDT by StewartTR]

Originally Posted By LoadedDrum:
I always thought of the sole purpose of a 11.5" barrel was to still have a compact carbine when you stick a 5.5" sound suppressor on it. I will never understand the point of a 11.5" barrel and a 5.5" flash hider.



Looks

If you read www.ammo-oracle.com you will see that 11.5" barrels barely get bullets to the minimum fragmentation velocity and 10.5" or less are hopeless.
Link Posted: 2/24/2006 4:55:17 AM EDT

Originally Posted By KorpiszZ389:
First, would the 11.5" be a good move, or should I just stick with the 14.5"?



Cleatus, I'd stick with the 14.5 for two reasons.

1. Obviously better velocities!

2. 11.5 is TOO friggin' loud for in the house!
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