Best barrel length for 9mm sbr?

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Maverick1911

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I wouldn't fiddle with a 9mm AR that isn't the Colt pattern. You'll always be able to get parts for a colt pattern gun.

I have shot mine at steel out to 200 yards. Did fine with open sights. It's the only part I kept from my 9mm AR when I parted it out. Sitting in the safe waiting to be used again one day. Or auctioned off to the highest bidder I suppose.

I'm new to the pistol ar build so excuse my ignorance when I ask what does a "colt pattern" mean? I know for .223/5.56 builds everything is pretty much interchangeable. I have a cmmg dedicated 9mm lower...,will the tros work on that? And the 3 lug barrel....is that better than just a threaded barrel?
 

Maverick1911

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Check this out for velocity info at various barrel lengths:

http://www.ballisticsbytheinch.com/9luger.html

On average, the biggest drops in fps per inch of barrel lost are from 13" to 12" and 9" to 8" inch and then then after 7 inches the loss climbs increasingly (though 5" is a relative sweet spot).

Here's what you loose in fps for each length compared to a 17" barrel:

16": -14.2
15": -16.3
14": -13.2
13": -18.4
12": -44.5
11": -51.4
10": -62.4
9": -64.3
8": -80.9
7": -96.8
6": -125.3
5": -151.2
4": -210.7
3": -279.5
2": -365.1

I suppose the length isn't so important if you plan on shooting subsonics. (?)



Thanks for that data! I'm trying to decide between a 5 or 7 inch barrel. Add a suppressor on the 7 inch and it really isn't that short anymore!
 

BigDiezel

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Your Cmmg lower would be Colt pattern. There's a couple more out there like Olympic and the glock mag lowers, maybe some others aswell but most just run the colt style. The tros barrel will work , Go 5" and tros or threaded it would be personal preference I'd say.
 

Super Dave

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I wouldn't fiddle with a 9mm AR that isn't the Colt pattern. You'll always be able to get parts for a colt pattern gun.

I have shot mine at steel out to 200 yards. Did fine with open sights. It's the only part I kept from my 9mm AR when I parted it out. Sitting in the safe waiting to be used again one day. Or auctioned off to the highest bidder I suppose.

What Dustin said. You can get Colt style anywhere. The Glock style, albeit is neat, is "special". If there is any weird part for it, say a bolt for example, will you be able to replace it in 5 years if something breaks? 10? 20?

My barrel is a RRA. They call it a 10.5", but they must be comparing it to a 5.56 barrel/bolt. From the bolt face it is actually 11.2", or somewhere there about. I am supremely happy with it. Although I bought 4 magazines from Spikes (Metalform) that were great, but a gazillion $ each, I have 20 or so Uzi mags that I modified that work just as well (but no BHO). I want to say they were $5.20 each at the time. Good luck finding that deal now.
 

338Shooter

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Colt style.

i306_photobucket_com_albums_nn269_dustingaunder_Guns_20and_20R2d0865c76f69df9e52d943c5f64129bd.jpg
 

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