For "burp control" on the epoxy pumps I dispense a pump or two into a mixing cup and return it to the can (keeping separate resin and hardener cups of course).

I have mounted a funnel on the top of the can to make this convenient to do. The funnel is small enough that it doesn't interfere with pumping but large enough to accommodate the plastic yogurt cups that I use for mixing. I just pump a shot into the mixing cup then turn the cup upside down into the funnel to drain back. The funnel provides venting and the mixing cup acts as a plug.

Burps aside, I have found the pumps to be very consistent in metering. Regardless, I ALWAYS use a "measuring cup" marked in the way that Ross described in his post. The idea of cleaning up a batch of epoxy that did not cure properly does not appeal to me.

The pumps can be put out of calibration by excessive force. The viscosity of the epoxy changes noticeably with its temperature - don't apply pressure faster that the pump can deliver the resin.

Hope this helps.

Hank