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Old November 2, 2002, 10:40 AM   #1
Hard Ball
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AR15 Barrel Length vs Ballistic Effectiveness

Much of the effectiveness of an FMJ .223 bullet comes from yawing and bullet fragmentation. To get these effects the bullet must strike the target at at least 2,700 feet per second or more. From a 14.5 inch barrel you drop below 2,700 fps at @ 60 yards when firing M855 ball ammunition. An 11.5 inch barrel's performance is worse,
If you are buyinf an AR15 as a deffensive weapon 16 inch and 20 inch barrels are a much better choice.
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Old November 2, 2002, 11:08 AM   #2
Art Eatman
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If you're buying any AR as a defensive weapon, why aren't you buying soft-point ammo? Anything over, what, 2,200? 2,300? ft/sec, and it expands quite nicely. You're not worried about the ethics of a "clean kill", right? You're trying to stay alive.

Why would somebody worry about full-patch ammo for self-defense? Money? Duh? Cheap is for practice ammo, gaining proficiency at shooting multiple targets at various ranges from awkward postions. When it gets to the Real Deal, the last thing I'd want to have on my mind was the cost of my ammo.

Self-defense ain't gonna be a 1,000-round fire-fight.

Match the ammo to the gun and the package to the probable worst-case scenario. Probable, I said, not Hollywood.

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Old November 3, 2002, 03:01 AM   #3
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Yeah, for "all arround" use I like the 16".
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Old November 3, 2002, 11:40 AM   #4
PeteyPete
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I bought a 16" shorty figuring it's a nice compromise between the 14.5" and standard 20" barrel.
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Old November 3, 2002, 11:41 AM   #5
Steve in PA
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Do you really think 1.5" (14.5 vs 16) really matters that much??? I mean, just how much velocity are you loosing to that 1.5"??
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Old November 3, 2002, 11:53 AM   #6
Redlg155
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For the military shooting at extended ranges the 150 to 200 fps loss in velocity make make a big difference in bullet performance.

Especially with the newer "Green Tip" penetrator type ammo.

For the Civilian at home just load up with some good Soft Points and be done with it. If you are engaging targets at 300 meters at home, you've got some serious problems. You might just need a bigger gun.

I'd have bet a lof of those boys over in Somalia wished they had M14s.

Good Shooting
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Old November 3, 2002, 01:31 PM   #7
Jamie Young
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Quote:
Match the ammo to the gun and the package to the probable worst-case scenario.
Something nobody does.

I get a little tired of seeing all the M4 Clones and the SHTF setups with cheap ammo. Use the M4 for what it was intended to be used for. Its a house sweeping gun if you ask me. Once you get down to the 14.5inch barrel, ammo selection is crucial in a life and death situation. If I wouldn't hunt a deer with a rifle I wouldn't want it as a SD weapon.

The streets of Mogadeshu was the perfect example of the wrong weapons being used. They originally were to be just doing "house sweeping" until things turned ugly.

I actually have just started reading "Black Hawk Down," and I have yet to read anything bad about the standard M16A2.

My Bushmaster XM15E2 feels like a toy compared to my DSA STG58. If I want to go light and handy, I'll take my 18.5 inch Mini 14. If I want to jump out of helicopters, or wear body armor, I might want to change the rifle stock to the M4 style. In the summer time, the M4orgerys that I've fired were the most uncomfortable rifles I've ever fired. It felt like I was shooting off of a pogo stick. I shot a Daiwoo a few weeks ago that had a much better fitting stock.

Quote:
Especially with the newer "Green Tip" penetrator type ammo.
I shoot that round more than any other .223 round. I've probable put more than 4000rds of it threw my Mini 14. Its far more accurate than any of the 55gr stuff past 300yds. I can put all my rounds in a 12inch target at 500yds with my AR, but the 55gr stuff just blows away in the wind. The M855 is a better round than the M193 past 300yds as far as accuracy. It may mean something in War like situations, but for self defense...... its simple not the best round.
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Old November 3, 2002, 08:19 PM   #8
flinch_of_gt
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Just so that people know...

M193 out of a 11.5" bbl gives you a maximum effective range of about 45 yards.

M855 drops to 25 yards.

Short barreled ARs are best used for entry teams/CQB.
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Old November 3, 2002, 09:12 PM   #9
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Quote:
M193 out of a 11.5" bbl gives you a maximum effective range of about 45 yards.
M855 drops to 25 yards.
flinch_of_gt:
What do you base that statement on?

The data I have (from an article about M2 Corporation).
Their M16SP, 8.4" barrel velocity data:
Ammo:.....Muzzle:.....100 yards:
M855.......2550 fps....2319 fps
M193.......2591 fps....2329 fps

(From GWLE, Feb 2001, p.43)

I can't verify this data untill the barrels (11.5") I have coming in arrives. Then I will duplicate some of these tests. (Which I'll of course poste on TFL).

I bet that the data for a 11.5" is better than the 8.4"
I'm not saying a shorty is a long range gun, but merely that if you need to, you can also use it at longer ranges.

K.
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Old November 3, 2002, 09:40 PM   #10
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I never liked to fight with .223 in nam, always grabbed an m14 if I needed to go out with a rifle.20 m14 mags are heavy though. IMHO a short barreled .223 is kinda like going in harms way with a .22 hornet. I have an m-4, a flattop HBAR, and an old delta style A2 . the m-4 is nice for my motorhome, but I think you dont get that high velocity impact effect below 2800fps IMPACT velocity so 20" at at least is necessary for .223 at normal 100 yd up ranges.I think .223 is best from 25 to 125 yards from 16 up barrels.
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Old November 3, 2002, 09:50 PM   #11
flinch_of_gt
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Data from http://www.ammo-oracle.com/#velocity

(distance to 2,700 fps)

For M193, 11.5" bbl, 45 yards.

For M855, 11.5" bbl, 15 yards.
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Old November 3, 2002, 11:45 PM   #12
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OK flinch, god data.
But, whom exept military forces would choose M855 or M193 over HP/SP/frangible bullets?

Pick the right tool for the job. That is why I have more than one gun...
Using a long gun indoors can be difficult, and even 4" makes a big difference.

K.
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Old November 3, 2002, 11:54 PM   #13
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Quote:
old delta style A2

What is a Delta style A2?
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Old November 4, 2002, 12:04 AM   #14
gordo b.
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Thats the original triangular(delta) handgaurd, forward assist M-16 with 1 in 12 twist.I think I should have said M-16a1.
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Old November 4, 2002, 10:35 AM   #15
Hard Ball
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M193 ball has superior wound ballistic performance to many .223 commercial SP loadings particularly at striking velocities of 2,800+ feet per second. The performance of SP bullets in AR15s is variable to put it mildly. Much of it was designed for 1 in 12 inch twist barrels. Performance may be very poor in 1in 9 or 1 in 7 inch barrels.
If you intend to use SP ammunition in an AR15 select it carefully and test it thourgly on ballistic gelatin or deer size game before you decide to bet your life on it.
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Old November 4, 2002, 11:15 AM   #16
Brian Busch
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Quote:
If you are buyinf an AR15 as a deffensive weapon 16 inch and 20 inch barrels are a much better choice.
I don't think so. Justifying 60+ yard self defence shots are gonna be pretty hard to prove after-action

Also, the proper load for an M4 is M193, not M855. The M855 ammo was designed to be used with the M249 5.56mm SAW (MINIMI). Muzzle velocity of the M193 out of a 14.5" barrel is well over 3000FPS. In my experience, and that of others who's chrono data I've seen, M193 drops around 300FPS per 100 yards regardless of barrel length, making the 2700FPS barrier for the 14.5" barrel right around 100M. I have it on good authority that the M4 is plenty within 150M if you do your part (COM hits).
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Old November 4, 2002, 11:40 PM   #17
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Keep in mind that the military is actively field testing the heavier 75 and 77gr loads (Hornady BTHP and Sierra MK) in Afganistan, and supposedly are quite happy at how those loads are performing, in the real world, against actual people, out of the M4. The heavier, longer, thin jacket bullets seem to be much, much more insensitive to velocity loss than the ball (M855) loads. So perhaps the M4 does have a future after all...
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