How important is rifling rate of twist?

[DaveN]

Thanks to both for the outstanding info. Apparently I had it backwards or was told it backwards. I did just get off the phone with Olympic Arms and was told though I will confirm with above test that I should have the 1 in 9 twist which I now understand is what I need for the 62 gr ammo I purchased.
A funny thing I also learned.... my Oly Arms PCR 01 stands for Politically Correct Rifle.
That and the T-Shirt that says ATF ( alcohol, tobacco and Firearms) "Who's bringing the chips?" leads me to believe that gun owners are funny as well as responsible law abiding citizens.

In conclusive as I just tried and the .22 brush is old and worn and started to twist but never made it around after 16 inch pull. I've been using a bore snake so will have to buy a new brush if you think that may be voiding the test result.