Trijicon themselves say "the ACOG isn't a sniper scope" ...from their mouths on "Shooting USA"
On their website they say:
» 03. What bullet was used to calibrate the ACOG scopes?
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).
» 04. Does bullet weight and/or barrel length effect the reticle bullet drop compensator and range finding stadia lines?
The real issue is not the bullet weight or barrel length, but muzzle velocity, ballistic coefficient, and the distance from height above bore. The difference in trajectory from bullet to bullet or barrel to barrel is usually less then the MOA thickness of the stadia lines.
Bold pretty much sums it up. The kind of practical shooting these were designed for, the rifles and ammo typically used with them all add up to differences larger than the difference in the BDC, which is often smaller than the stadia lines themselves.
If I recall correctly, tritium has a half-life of 12.5 years. That means, in 12.5 years, it will be half as bright. Double that should be the total life. But, that is irrelevant since at some point you lose the usefulness of it when it gets too dim. If this is from 1993, that makes it 15 years old at least. It is less than half as bright as it was when it was new. Or half as bright as a new model made this year.
Regardless, the ACOG is a great scope even if it were relegated strictly to day time duty. It's a good deal if you're not overly concerned about early dawn, late dusk or night time shooting.
However, a new one runs about $840. Factor in that this is used even if in mint condition and if you care about the illumination, it is likely going to need a tritium replacement soon.
Tough call. Depends on your use and expectations.
