DeerT: Best way I have found to do a reasonable fightin purr: sit back against a tree. Hold a quality slate between your knees and use different strikers in the left and right hands. Purr and putt LOUDLY with both strikers, occasionally stopping to pop LOUD wing beats with canvas cloth against a knee. The technique does not always work, but when it does, hung-up birds can come a runnin' . I watched a knocked down drag out gob fight, and pattern the cadence after what I observed. Of course, you have your hands full of strikers, and not a gun (or bow), so use the technique with a partner. The dual push-pull calls are not near as loud, nor do they have the staying power of a good slate before they need a tune-up. I have tried it as a fall call, but lost calling does the job in the fall for me.
-fsh