High Power shooting and the mirage

[Frank_Symptoms]

I've recently bought a TC Contender carbine in .223 Rem. Here in the People's Republic of Kalifornia, most of our shooting is confined to hot canyons... where mirage is murder. I came across the topic when I  was shooting at a DCM match, but don't remember much about it.
My question is, how much does mirage affect your aim? I recently read that it's only 1-2 MOA but it seems to me that I'm getting far more affect at 100 yards than that. Or maybe I have a rotten barrel? At 100 yards most rounds are inside the 8-ring (5").

[Jose Grande]

If the mirage is going straight up, it gives little problem. But in a 3-5 mph crosswind it waves & that can cause a problem. I'd try a good solid rest early one morning, to see if the gun is doing it's thing. You don't say whether you are using a rest or not. If not, you're doing just fine.

[jeff]

Mirage makes the target appear where it really isn't.  If the wind or breeze or lack of a breeze is constant and mirage is present, then the resulting group should be no different than a group fired under ideal conditions.

Quality of ammo is important, both bullet and powder charge.  Example, Sierra 52 gr Match Kings vs. Remington 55 gr FMJ's.  The best I've ever gotten from the cheap stuff is about 2 1/2 to 3" at 100 yards.  The Sierra MK's always shoot about 1/2" in two of my rifles.  

I had a problem with a new 20" 223 Bullberry barrel for my Contender Carbine and was getting 5" at 100 yards with good ammo.  Then I realized that there was a lot of slop in the barrel/action fit.  After installing an oversize hinge pin, the groups came down to just under an inch.  See the Contender Carbine board, 'New Barrel Problem'.

Hope this helps you.