Quoted: I thought the TA01's BDC was designed for a 20" barrel firing M193, mounted on the M16 carry handle. If so, then how does the BDC work when shooting M193 from a flatop with a 16" barrel, and when using 75gr also? Aren't the velocities lower and shouldn't the POI change? I have a TA01 on a 20" Gov't model and haven't had the opportunity to shoot farther than 200 yds yet.

I know about what the TA01's BDC is "designed" for - as far as what is written in the manual for mine.

I was not shooting for match accuracy or consistancy. Lets get that straight. I was simply seeing if I could aim and generally hit what I was aiming for. I experimented with the BDC marks in the reticle to see where they would hit. I was able to use the second to last line (I believe it was), to hit the 550 yard berm consistantly. From there I aimed up higher to the top of that center/left hill, just to the left and back from the truck tire and was able to use the first person-sized circle in the post to hit that spot consistantly. Now, take in mind I am not aiming at paper and am just going off the puff of dirt that is shot up when I hit that area. For whatever reason I was able to use that BDC point in the reticle to hit that distance every time I aimed there with XM193 55gr FMJ ball.

ETA: My ACOG was also sighted in at 100yds first with the XM193 as well. If you sight it in at 100yds for 75gr as well, I think the BDC is going to be off a little but not too much. At the end, I popped in a mag of BH 75gr OTM blue box and was able to generally hit the areas I aimed for including the gong/truck tire (which had a slightly louder report back) without even sighting it in first. It wasn't perfectly on like the XM193 but the POI was generally the same, with slight adjustment.

- rem

I've heard some claim that M855 will maintain 4 MOA at 600. In your experience, does that claim hold?

Yup. 600 meters (ca. 660 yards) 10 shot groups w/ Lake City M855, my 20" bushy flattop and a TA31RCO ran around 18" or so. I am confident that with practice, I can hit the chest (shoulder to shoulder) of a man-sized target 75% of the time at 800 (half mile). In short, M855 holds 4moa pretty far out.