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Posted: 11/18/2007 8:40:52 PM EDT
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Is the TA31DOC calibrated for a 20" or 14.5" barrel? I'm going to build an A4 clone and I'm trying to decide between the DOC or the TA31RCOA4. |
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From Trijicon: The TA01, TA11, & TA31 (.223) were designed for the 5.56mm, 20 inch barrel, 55 grain bullet, and M16/AR15 carry handle mount. The TA01B & TA11C(.308) were designed for the 7.62mm, 20 inch barrel, 168 grain bullet, and M16/AR15 carry handle mount. The TA01NSN was designed specifically for the US Special Operations Command SOPMOD M4 Carbine. To meet their requirements, the reticle bullet drop compensator and range finding stadia lines were based on the trajectory of the 62 grain bullet from a 14.5 inch barrel, flattop mount (Picatinny rail Mil.Std.1913). Edit: Info above is outdated and is not correct.  Trijicon: Update your site! 
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I want to say they are setup for a 20” but I cannot find any info on what they are setup for. If I come a cross it I will post it. Mike @ CSGW www.csgunworks.com [email protected] Here’s some testimonials about CS GunWorks What do YOU have to say about CS GunWorks What Do You Think Of Cs Gunworks? FEEDBACK about CSGUNWORKS.com |
Did you not like the answer I gave from Trijicons website? |
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MOLLE Its not that they didn't like the answer its that it is inaccurate and outdated. According to the info I had on my TA31DOC The TA31DOC is calibrated for an M4 14.5" barrel and M855 Ball round. Now lets talk about Calibration. People get way to hung up on this. Just because a scope is calibrated this way does not make it unusable for other barrel length. When using my TA31DOC on a 20" barrel I found if I took a 6 O'clock hold on a target out to 500meters I was dead freaking on. The difference in bullet drop is minimal out to 300 meters, about the difference of the width of the stadia line. If you use any f the TA31 or TA11 series and you can tell a difference out to 300meters you should not be using an ACOG. |
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Ahhhh. I didn't know if I just stink. Thanks for setting me straight. And FWIW, I too checked my user manual on my TA31DOC and it also says 14.5 with M855. With that said, I used it at set distances....100,200,300,400 yards with a 20 inch barrel and it was dead on. Isn't the BDC based solely on velocity? |
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TA31RCO-A4 is "more" correct for an A4 clone, having been designed for it. However, you can still use a TA31DOC, it will be only slightly off. Not to mention, the BDC is not exact unless you're using the same ammo as well as the same bullet length. TA31DOC - M855 62gr NATO 14.5" 1/7 barrel TA31RCO-A4 - M855 62gr NATO 20" 1/7 barrel HTH, ~Augee |
Your info is just fine; it is Trijicon’s info that I have a hard time with at times. Trijicon will also say the TA31 is only for the carry handle AR’s so the BDC will not work flattop. The TA31 work just fine on a flattop.
Like you said your ACOG that is setup for a 14.5” works just fine for you 20” at 100 to 400yds. This is the case with any of the ACOG’s BDC, if it is for a 223 14.5” or even the 308 it will work just fine out to 400yds. Where I have seen a difference is at 500yds and out. Mike @ CSGW www.csgunworks.com [email protected] Here’s some testimonials about CS GunWorks What do YOU have to say about CS GunWorks What Do You Think Of Cs Gunworks? FEEDBACK about CSGUNWORKS.com |
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