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Posted: 9/25/2012 10:11:55 AM EDT
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Sorry for some dumb questions...total newb here (this is, in fact, my first post here).
I currently have an AR-15 chambered in .223 with a 16" barrel. I'd like to replace it with an 18" or 20" barrel. What do I need to know and do to accomplish this? Do I need a .223 barrel or will 5.56 work? Through this gun I'll mostly be shooting 45-55 gr bullets, so 1/9 twist will work. But is there any downside to firing lightweight bullets through a 1/7 twist barrel? Any other suggestions or recommendations? Thanks in advance! |
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Welcome!
Here's a guide on how to change your barrel in the build it yourself forum. There's no reason to not get a barrel in 5.56 in my opinion. It is the more versatile of the two, and a .223 chamber offers no real advantage. Molon's thread regarding 5.56 vs. .223 I have never shot projectiles that light through my rifles (which are all 1/7 twist), so I can offer no firsthand experience on their performance. Here's the breakdown in the ammo forum. |
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Few barrels are made with a true SAAMI 223 chamber anymore. If you're looking for a precision rifle you'll probably be looking for something with a Wylde chamber, or a modified version of the Wylde for improved accuracy and no questions about compatibility with ammunition made to military pressures.
Optimum barrel twist is really going to depend on how serious you are about just shooting lighter weight bullets. If you're really looking for optimum results with 45 to 55gr standard lead core type bullets, you would go with something like a 1:12 twist. But you'd be limited to 55 to 60gr or so (lead core) bullets at the longest. A 1:9 twist would let you use bullet lengths up to the low 70's gr (lead core) and would be ideal for something like the 69gr match types. A 1:8 twist would let you use any factory loaded ammo as well as essentially anything that would fit in a magazine (and beyond). The faster twists do start to sacrifice a little of accuracy (noted more strongly with less precisely made bullets) and have some long range trajectory effects on lighter bullets. Personally I'm not a fan of 1:7, its just not needed and (IME) produces a wider variation in performance with lighter/shorter bullets. |
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