So here's the deal. I'm building a 9mm AR out of a Bushy lower and RRA upper. Later I intend to chop the barrel and form 1 it. Does anyone have any chrono numbers showing the optimal barrel length for the 9mm. I think I remember someone on here saying it was 8". More that likely I'll cut my M4 to just in front of the front sight which will make it around 10" I think (haven't measured). Anyone know the barrel length that 9mm likes. Also if 10 is longer than optimal by what rate will the bullet begin to slow.
Optimal 9mm Barrel
- Thread starter Ryu
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Here is a thread that I posted a couple years ago. It doesn't answer your question, but will at least give you something to go on. You will have to scroll down a little bit to get to the 9mm stuff.
I chronoed loads from various 9mm handguns and an AR15 with a 16" barrel.
http://www.thehighroad.org/showthread.php?t=45283&highlight=chrono
I am going to do the same thing with this AR15 I have (Colt Lightweight Sporter: factory 9mm AR). I am going to cut the barrel down to the same size as the Colt SMG. What that length is, I don't know right off hand, but my local NFA dealer has one.
EDIT: Ask Google and you shall receive. The Colt SMG has a 10.5" barrel: http://www.srtsupply.com/pages/firearms/colt_full_auto.htm
I chronoed loads from various 9mm handguns and an AR15 with a 16" barrel.
http://www.thehighroad.org/showthread.php?t=45283&highlight=chrono
I am going to do the same thing with this AR15 I have (Colt Lightweight Sporter: factory 9mm AR). I am going to cut the barrel down to the same size as the Colt SMG. What that length is, I don't know right off hand, but my local NFA dealer has one.
EDIT: Ask Google and you shall receive. The Colt SMG has a 10.5" barrel: http://www.srtsupply.com/pages/firearms/colt_full_auto.htm
Don't have the info handy or would post specifics. I own a PC9 and Keltec Sub2000. Both with 16.5 inch barrels.
Compared to a Glock 17 you see a velocity increase in the carbines longer barrels. With 147 gr. factory ammo you don't see much, usually around 50 fps. Hotter varients may push it up to 100 fps, though usually it is no more than 75 fps. The lighter 115 gr loads see a greater increase. The 115 gr. ammo usually gets you around 150 fps with some of the hotter reaching 200 fps.
Unfortunately just data from this one long barrel length doesn't tell us if you would gain more speed with more barrel length or less.
Compared to a Glock 17 you see a velocity increase in the carbines longer barrels. With 147 gr. factory ammo you don't see much, usually around 50 fps. Hotter varients may push it up to 100 fps, though usually it is no more than 75 fps. The lighter 115 gr loads see a greater increase. The 115 gr. ammo usually gets you around 150 fps with some of the hotter reaching 200 fps.
Unfortunately just data from this one long barrel length doesn't tell us if you would gain more speed with more barrel length or less.
shoobe01
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Pistol calibers work great out of short barrels, so an 8 or 10 inch barrel is much more speedy and accurate than a 4" pistol.
.45s start to loose speed after 8-9". 9mm I think doesn't do this until over 16", so its all good. Pick one that makes you happy.
Yes, it will vary some based on rifling type, bore tolerances and so on.
.45s start to loose speed after 8-9". 9mm I think doesn't do this until over 16", so its all good. Pick one that makes you happy.
Yes, it will vary some based on rifling type, bore tolerances and so on.
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