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Posted: 5/8/2017 1:12:30 AM EDT
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Noobie questions:
I'm building a basic AR for Service Rifle matches. Is there a mandated barrel length, or can I choose between 20" and 16"? Of those two lengths, which might be best? 1:8 twist for 500 yards/69 grain projectiles? Or would 1:9 work just as well? |
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I don't know the rules, but I don't think a carbine would stand a chance against a rifle. Look at the sight radius.
Probably post your question here http://www.ar15.com/forums/f_9/2_Competition-Basics.html Or here. http://www.ar15.com/forums/f_9/14_High-Power---DCM---CMP.html |
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There's a little grey room as to what's an "M4" and "M16" configuration, but I prefer to stick with what's sure and more aligned with the "spirit of the rules".
If you're a small guy, a 16" carbine will fit better. For irons, a 0.040" aperture and 0.052" post works well with the shorter sight radius. 0.25 MOA clicks are closer to 0.3 MOA or 0.1 Mil, and 0.5 MOA clicks are closer to 0.6 MOA. Optics are getting reliable enough that you could pretty much disregard this if going that route, but I like having a backup. The slower velocity is worth about another 0.5 MOA in a 10 MPH full value wind - a ring worth. 20" is the standard. For both lengths, 1:8 twist is optimal for 75/77gr HPBT. If you want to use the 73gr ELD or 77gr TMK, or 80gr single loaded bullets, get a 1:7.7 or 1:7. All three twists will shoot 69gr SMKs well. The state championship is in a couple weeks, May 19th, 20th, and 21st, at Camp Swift, east of Austin. |
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Many thanks for all the great information and suggestions.
Yep, according to another source (shooter friend), 16" isn't even allowed in sanctioned matches. So... 20 it is. And probably 1:7 or 1:8 twist. I have 'tons' of 55gr FMJ BTs and even more 77gr HPBTs. Not quite ready for the TSRA match. Don't even have a glove yet. PS: I can't find the 'subscribe' button any more. I didn't know there were any responses already. Good thing I checked back here! |
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I assembled this Tuesday and got a rough 100yd zero Wednesday before leaving Thursday. I participated in the Saturday individual match which was shortened to 50 shots plus sighters. With a difficult magazine, some positional quirks, and "squishy" MOA clicks, I managed 450-5x. Windage-wise at 600yds, I was seeing 2 MOA shifts and stayed within edge-of-9 to edge-of-9 for most shots. I think I'll try it at the local walk-and-paste to give it a fairer benchmark.
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Quoted:
I assembled this Tuesday and got a rough 100yd zero Wednesday before leaving Thursday. I participated in the Saturday individual match which was shortened to 50 shots plus sighters. With a difficult magazine, some positional quirks, and "squishy" MOA clicks, I managed 450-5x. Windage-wise at 600yds, I was seeing 2 MOA shifts and stayed within edge-of-9 to edge-of-9 for most shots. I think I'll try it at the local walk-and-paste to give it a fairer benchmark. https://www.AR15.Com/media/mediaFiles/379478/20170518-130227-213719.JPG https://www.AR15.Com/media/mediaFiles/379478/20170520-142834-213720.JPG |
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