Ammo for Zeroing

[neomedic]

What is a good ammo to use to zero my AR?

It's a RRA Tactical Entry Carbine Length Upper (1:9 twist). The Lower probably doesn't matter, but it's a CMMG lower with RRA National Match Two-Stage trigger.

Also, on the upper is a Daniel Defense 7.0 Quad Rail and it came with ladders. But the rubber ladders are too long for the Rail, what is the best way to trim them down to fit? Which rung should be cut? (Do you cut the rung before the last "hole" in the picatinny rail or after it??) Don't know if I'm making sense...if I get a chance I'll post a pic.

Thanks.

[Technical Ted]

What is a good ammo to use to zero my AR?

The ammo you plan to shoot.

It would do you absolutetly no good to zero with something like Federal Gold Medal Match or Black Hills match ammo then turn around and shoot the cheapest Wolf steel cased 55 gr you can find or vice versa.

[bobfried]

I zero with what I consider my go-to stash. So it's M855 for zeroing, RG and Wolf or anything cheap for plinking.

[Jicko]

+1 on Technical Ted

-1 on bobfried

There is a huge POI difference between M855(62gr) vs M193(55gr) and other commercial 55grners.

Zero with the ammo that you are planning to use with your gun, that's the ONLY way to go.

[CSACANNONEER]

The ammo you plan to shoot.

It would do you absolutetly no good to zero with something like Federal Gold Medal Match or Black Hills match ammo then turn around and shoot the cheapest Wolf steel cased 55 gr you can find or vice versa.

+1 Every time you change your load, you need to check your "zero" and adjust as needed.

[sammy]

That is a super nice upper. Mine is chrome lined with a 1/7 lightweight and loves the Guat. surplus but I think that stuff is long gone.