I buy lean roasts on sale and grind them myself (with a grinder attachment to a Kitchenaid Mixmaster).  I use a jerk "shooter" with commercial jerky mixes and have rave reviews.  This is far more consistent than slicing.  I can dry a batch in less than 6 hours.  Be careful of the commercial mixes...some of the spice packets have added salt.  Use the appropriate amout of salt cure and mix up your own spices to your taste.

beefman