AR Ballistics - 14.5" vs 16"


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sully0812
July 12, 2007, 12:10 AM
I know this data is out there, but I've searched for it in vain.

I'm looking for some solid and reliable comparisons between a 14.5" bbl, and a 16" bbl on a standard carbine-length-gas-system AR.

A graph would be nice.

I'd like to know velocity comparisons, and range/bullet drop.

Typically, most of my shooting is done with 62 grain bullets. At what range will I notice a significant difference?

How about noise? SBRs can be pretty brutal. Is there a significant increase in decibles when going from a 16" to a 14.5" with a perm flash suppressor?

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otomik
July 12, 2007, 01:27 AM
if you are wondering if doing the SBR thing is worth it you don't have to agonize about it so much.

a real M4 carbine has a 14.5 inch barrel plus a A2 flash hider

a Bushmaster M4gery has a 14.7 inch barrel plus a slightly longer flash hider permanently attached.
http://www.bushmaster.com/shopping/weapons/bcwa3f14m4iz.asp
with the permanently attached flash hider it comes to 16 inches but has virtually the same ballistics as the M4.

there is a problem with your question that makes it inexact and difficult to answer because we could be comparing 14.5 inch ballistics to anything from 14.7inch to 16 inch.

salty
July 12, 2007, 09:20 AM
I have a gun mag from a few years back where the author cut the barrel down inchwise from 22" to 10" on a 223 bolt action rifle - he collected data for different powders, bullet weights, velocity and accuracy. Very illuminative data - 1 1/2 inches shorter in that range would be about 60 fps w/o a flash hider using a standard ball powder with a 55 fmj gr. bullet.

DogBonz
July 12, 2007, 09:44 AM
Check out this chart from "The Book of the AR"

Enjoy.

http://www.thehighroad.org/showthread.php?t=269336&highlight=chart

sully0812
July 12, 2007, 11:18 AM
there is a problem with your question that makes it inexact and difficult to answer because we could be comparing 14.5 inch ballistics to anything from 14.7inch to 16 inch.

I'm not sure I understand. My question was pretty specific in regards to 14.5" vs 16", not anything in between.

sully0812
July 12, 2007, 11:20 AM
Here You Go

Check out this chart from "The Book of the AR"

Enjoy.

http://www.thehighroad.org/showthrea...ighlight=chart


Cool, some good information there!


Does anyone have any first hand knowledge regarding the noise, and if a 14.5" is appreciable louder than a 16"?

GRIZ22
July 12, 2007, 01:05 PM
Velocity with 55 gr NATO ammo runs about 2800 fps in each length. You may find velocities higher in some 14" barrels over 16" as there are variables in barrel manufacture. The problem with either is 2800 fps seems to be the threshold that causes severe fragmentation in the target which gives the 223/5.56 a lot of its stopping power. No difference in noise level with such a small difference in length.

$200 is a lot to pay for 1 1/2" less barrel with other restrictions that may apply.

RockyMtnTactical
July 12, 2007, 01:56 PM
The frag threshold is 2500-2700fps (2700fps and higher being more reliable and devastating fragmentation), and most 14.5"-16" barrels do closer to about 3000-3100fps from the muzzle, not 2800fps.

You can still get fragmentation out to 100 yards or so with a 14.5" barrel, well past any more likely combat ranges...

Besides, shot placement will almost always trump fragmentation anyways.

http://i2.photobucket.com/albums/y18/mwirig79/BallisticsAB.gif

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