I have K&M now. Have used Sinclair but "loaned" it out. Either works well. Particularly on drilled flash holes.

Good news, bad news,
The Sinclair flash hole uniformer/reamer is length tolerant. The bad news is that you have to twirl it by hand (it chokes on brass chips if you try to power it up).
JCN

I've got the Lyman uniformer and it works pretty well. In theory your supposed to have all of the cases the same length, but the bit is such that you can get away with them being otherwise.

I've been using the Sinclair tool for close to twenty years, with good results.

K&M makes a length tolerant uniformer, it is intended to be used by hand, but I have has some luck chucking it up in a power screw driver. Quality is excellent, has a free floating collar that centers the case.

I'm looking to replace the Primer Flash Hole Uniforming tool that I bought years ago. The one I want to replace was made with a center drill in a piece of aluminum tubing with a wire nut on the end. It was the first one that I had seen advertised. Now it seems that it gets harder to line up the cutter with the flash hole. I'm looking for one that does not require that each case is trimmed to the exact same length (I'm lucky if I can get the cases with .004 inches of each other!) I can keep them within the minimum to maximum measurements but not any closer. Is there one that meets my requirements or am I out of luck?

Dennis Mickey @ Littlestown, Pennsylvania

Another vote for the Sinclair here.

I use the Sinclair chucked in a varialble speed drill. I turn it slow and it does a good job. I admit I haven't used it in the last two years. I switched to Norma brass and found I couldn't improve on the pocket. The pockets were fairly uniform; enough so as to make messing with them a wasted on my time.

Another vote for Lyman, mine works fine.
I use it both manually and chucked up in an electric screwdriver.
No problems.

Covey16

I'm not sure this will facilitate the accuracy you're after but it is an option .When there is a fair number of cases to tumble I first remove the primers with a tool I made and a hammer. The tool has a slightly tappered pin that goes into the hole from the inside. The pin ends in a flaring head. Pin and flare head are one piece made on a 3/16" dowl rod. I place the case in a nest that allows the primer to drop thru. The pin is than inserted into the flash hole and banged with the hammer. You could build it out of a spring loaded center punch mounted in an arbor press. The pin sizes the hole and the peening section roles over burrs and such leaving a slight guide lead for your die decapping pins. For a bench rest competiter this may not be good enough but for everything else it is easy and seems to work. Ten minutes on a lath and you are there. roger