What Frank said!
Back in February Jeff and I went to the range to test a 6.5cm barrels. It was 17 degrees out. After about 7-10 rounds thru it and zeroing the scope (7-32x NF) I went to my first target and tried to shoot a 5 shot group. The mirage/heat coming off the barrel was so bad looking thru the scope that I was using the whole 1" paster at a 100 yards. I had to let the gun cool and then slow down my rate of fire and only shoot 3 shot groups.
Next time to the range and it was 47 degrees out but regardless of the temperature out side I put my mirage shield on the rifle (I have several for my F class guns). That stopped the mirage from messing with the sight picture. In the attached picture the mirage shield isn't on the barrel but you can see the velcro dots on the top of the barrel.
Wade Stuteville and George at GAP has done plenty of shooting and accuracy and getting the barrels hot and not a single accuracy complaint. Wades exact words to me where something close to "Every bit as good as our all steel barrels are!"
Funny but my mirage shields (my new ones) are carbon fiber also. Here is a link to a guy that makes them.
[email protected]
Later, Frank
Bartlein Barrels