Is there a performance difference between a 7" and an 8.5" barrel for a 556 pistol build? - Page 1

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[ARCHIVED THREAD] - Is there a performance difference between a 7" and an 8.5" barrel for a 556 pistol build?

Posted: 9/9/2017 11:02:49 AM EDT

I have an 8.5" pistol in 300 Black Out and love it. I now want a 556 upper for the same lower. I see 7 inch and 8.5 inch barrels. I don't want to go longer than 8.5 inches for storage reasons. Can anybody tell me the performance difference between these lengths....

Thanks

Posted: 9/9/2017 11:25:20 AM EDT

[#1]

You'll be on pistol-length gas system either way, so really the biggest difference is velocity. Probably about 200-250 fps difference with 55gr. ammo. The velocity drop for 5.56 really starts to drop off quickly once you go sub-10" or so.

http://www.ballisticsbytheinch.com/223rifle.html

Posted: 9/9/2017 12:46:49 PM EDT

[#2]

Thanks for the chart...looks like I want the 8.5 barrel......

Tony P.

Posted: 9/9/2017 3:31:33 PM EDT

[#3]

You should see how well a 20" fires

Posted: 9/9/2017 8:31:43 PM EDT

[#4]

I think the velocity gain is worth the 1.5" personally. I've owned both.

[ARCHIVED THREAD] - Is there a performance difference between a 7" and an 8.5" barrel for a 556 pistol build?

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