Velocity loss in 223 Rem with carbine barrel lengths?


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Balrog
February 26, 2010, 06:58 PM
Does anyone know approximately how much velocity you lose with a 16" barrel length as about to say a 20"?

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Birdhunter1
February 26, 2010, 07:33 PM
200 fps.

NCsmitty
February 26, 2010, 07:35 PM
You lose around 100fps or so, depending on the load.

Here's a link to an older thread, same question.

www.thehighroad.org/showthread.php?t=352353

NCsmitty

benEzra
February 26, 2010, 08:51 PM
Here's a chart from M4carbine.net comparing a 20" M16, 16" civilian carbine, and 14.5" M4:



http://i62.photobucket.com/albums/h86/PFC-JB/m193ballisticchartny2.jpg



BTW, the "fragmentation threshold" reference is to military FMJ, not civilian SP's or JHP's, which will expand/fragment reliably at much lower velocities than 2700fps.

Al LaVodka
February 27, 2010, 01:34 AM
I have often gotten disbelief from people who don't know the M4 is shorter than our AR Carbine's and that we have a slight advantage with one that is 10% longer.

:rolleyes:

Al

Ughh
February 27, 2010, 02:33 AM
That chart is weird... M16 is 16'' right? How is it faster than the following '16''' column?

Runningman
February 27, 2010, 05:08 AM
That chart is weird... M16 is 16'' right? How is it faster than the following '16''' column? The M16 uses a 20" barrel.

That chart is also very close to the difference I got between a Colt AR 20" HBAR and another Colt AR, 16" 6721. Using winchester USA 55 grain load on a slightly warm 82 Deg F day. I recorded 3263 FPS out of the 20" Colt. VS 3132 FPS out of the 16" Colt. For a difference of 131 FPS.

Ughh
February 27, 2010, 11:43 PM
Holy cow! I was always under the impression that the M16 was 16''. Stupid me :p

taliv
February 28, 2010, 12:51 AM
however, if you hang around the reloading forums, or people who own chronographs, you'll find that

1) 20 different rounds from the same lot of ammo may have more than 100 fps difference between the fastest and slowest measured

2) the average speed (constant ammo) through individual barrels of the same length may vary by 100 fps due to differences in chambers, rifling, lining, etc


i mostly just work on trigger control these days

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