Ammo, optics, and $$$

[hambam105]

That's funny, they would freak out.

Try it. Let us know what happens.

[FluorideInMyWater]

Be careful WHICH 62gr ammo you get.
Many 3gun matches use steel targets and they will not take kindly to you shooting M855 at their plates.

Personally, I load 55gr FMJ-BT to 3100fps and it matches the trajectory of M855 from a 14.5" barrel close enough to use hold-over reticles to 600yds.

are you referring to 55gr .223?

[FluorideInMyWater]

The Armalite AR-15 was designed with a 1:14 twist barrel to fire 55 grain .224 caliber bullets.

This means absolutely nothing to you as you do not have an original Armalite AR-15 and your barrel twist is likely somewhere between 1:7 and 1:9.

IIRC the 1:7 barrel twist was adopted by the military to better stabilize long for weight tracer ammunition with the added benefit of stabilizing heavy for caliber 75+ grain bullets used in some ammo.

Again, none of this matters.

Shoot a bunch of different ammo. Choose that ammo that shoots best in your rifle. Stack it deep. Do the math to calibrate your reticle/knobs.

when you say "do the math" do you mean don't use a sighting tool to zero it in? just your eyes?

[FluorideInMyWater]

What barrel length and twist?

62 gr doesn't mean SS109's (steel tips, AKA typically "green-tips") loaded as (X)M855, there is the SS109 projectiles and 62gr FMJ's also.

FYI: SS109 projectiles are not as accurate as 62gr FMJ's due to being tri-metal steel-tip (Copper coated steel tip, in front of lead, with a FMJ gilding)... If you want accuracy don't go SS109/(X)M855, but FMJ in 62 or 55gr, and sight-in with that. Don't over-crimp when you start reloading them, as I tend to.

you said
don't go SS109/(X)M855, but FMJ in 62 or 55gr, and sight-in with that
are you referring to 556 or 223 for the FMJ?

[NapalmCheese]

when you say "do the math" do you mean don't use a sighting tool to zero it in? just your eyes?

I mean use this site: http://jbmballistics.com/ and punch in your numbers (preferably after running your ammo over a chronograph), calculate the drop in MOA or MIL, and compare it to the subtensions in you reticle. You'll probably find the reticle is pretty close (depending on your definition of pretty close). Almost certainly "minute of torso" with pretty much every ammo out there.

[ar15barrels]

I mean use this site: http://jbmballistics.com/ and punch in your numbers (preferably after running your ammo over a chronograph), calculate the drop in MOA or MIL, and compare it to the subtensions in you reticle. You'll probably find the reticle is pretty close (depending on your definition of pretty close). Almost certainly "minute of torso" with pretty much every ammo out there.

And after doing that, you can load the ammo faster or slower until it matches the reticle subtensions as close as possible in the weather conditions you are most likely to be using it.

[FluorideInMyWater]

What barrel length and twist?

62 gr doesn't mean SS109's (steel tips, AKA typically "green-tips") loaded as (X)M855, there is the SS109 projectiles and 62gr FMJ's also.

FYI: SS109 projectiles are not as accurate as 62gr FMJ's due to being tri-metal steel-tip (Copper coated steel tip, in front of lead, with a FMJ gilding)... If you want accuracy don't go SS109/(X)M855, but FMJ in 62 or 55gr, and sight-in with that. Don't over-crimp when you start reloading them, as I tend to.

Barrel 16" 1/9 twist i think