Archived Posts » 59,726,163
Help zeroing in a TA-31RCO-M4
4/23/2012 3:29:45 AM
hello, i'm trying to properly zero a TA-31RCO-M4 on my 14.5" (pinned) LMT 1/7 twist upper using LC M855 as the BDC is intended for.
i cannot do an expedited zero per the manual at 33meters (36yds) as the 100yd range at my club does not allow shooting closer than 50yds. anything less must be done on the 25yd pistol range. i can move the target a bit past 100yd yards before hitting the berm so i can hit the 100m zero point to fine tune if necessary once getting a basic zero.
my question is what poa/poi difference should i shoot for on the 25yd range to best get a field expedited zero?
am i correct in assuming (after looking at a M855 trajectory from an M4 image from google) that my poi should be ~6" lower than the tip of the chevron as poa on the 25yd range to achieve this 100m expedited zero or am i incorrect?
any and all help to the ballistics gurus would be appreciated.
i cannot do an expedited zero per the manual at 33meters (36yds) as the 100yd range at my club does not allow shooting closer than 50yds. anything less must be done on the 25yd pistol range. i can move the target a bit past 100yd yards before hitting the berm so i can hit the 100m zero point to fine tune if necessary once getting a basic zero.
my question is what poa/poi difference should i shoot for on the 25yd range to best get a field expedited zero?
am i correct in assuming (after looking at a M855 trajectory from an M4 image from google) that my poi should be ~6" lower than the tip of the chevron as poa on the 25yd range to achieve this 100m expedited zero or am i incorrect?
any and all help to the ballistics gurus would be appreciated.
4/23/2012 5:18:44 AM
Just zero point aim point of impact on the tip of the post at 25 to get a field expedient zero and than refine it at 100 using the tip of the chevron.
4/23/2012 9:22:20 PM
if i do that (25yd zero using tip of post/300m bdc), should i be about an inch high at 100yds before adjusting? i ask due to the difference in lengths b/w the recommended 33m (36yd) zero and the 25yds (22.9m) i have available.
i know i'm probably looking this too much but i'm trying to see if i can do a 25yd zero, then come down what i would need before actually shooting a test string at 100m (109yds) to see if i'm dead on from the start.
i know i'm probably looking this too much but i'm trying to see if i can do a 25yd zero, then come down what i would need before actually shooting a test string at 100m (109yds) to see if i'm dead on from the start.
4/24/2012 4:24:33 AM
Originally Posted By eWRXshun:
if i do that (25yd zero using tip of post/300m bdc), should i be about an inch high at 100yds before adjusting? i ask due to the difference in lengths b/w the recommended 33m (36yd) zero and the 25yds (22.9m) i have available.
i know i'm probably looking this too much but i'm trying to see if i can do a 25yd zero, then come down what i would need before actually shooting a test string at 100m (109yds) to see if i'm dead on from the start.
if i do that (25yd zero using tip of post/300m bdc), should i be about an inch high at 100yds before adjusting? i ask due to the difference in lengths b/w the recommended 33m (36yd) zero and the 25yds (22.9m) i have available.
i know i'm probably looking this too much but i'm trying to see if i can do a 25yd zero, then come down what i would need before actually shooting a test string at 100m (109yds) to see if i'm dead on from the start.
You will a little off, but you are doing a pre-zero and not the true zero at the close distance. Also the Army uses a 25 M close zero. The close in zero is just to get you close enough to fine tune it at 100 meters.
Also the BDC on the sight is designed for "good enough for government work." based totally on averages and your ability to subtend distances for the autoranging.
