Use ours.
https://www.rcbs.com/reloading-dies/neck-bushings/neck-bushings/494.html
I have a decent amount of personal experience with the Matchmaster dies now. I came from using the Hornady dies for years and their micrometer adjustment. I prefer the Matchmaster now by far, and the concentricity is better than I have experienced with the Hornady dies. The loading window makes seating a total breeze. There's an internal floating sleeve that the bullet drops into and a C clip catches it from falling through. The sleeve aligns the bullet with the case before they ever meet so they go very straight. I've only ran the seater on the Summit press so far, and I've only done sizing on a Rock Chucker Supreme so far, and those were with the FL sizing MM die.
The first time setting one up took some trial & error to get the seating stem in the right place as it can be put into a few different height positions, and the depth of the seater die took some playing around, but the next 2 I set up went really fast from the experience gained on the first one.
Putting the bushings in is fairly straight forward and they fit great.
We're working on jazzing up the Matchmaster die product pages right now, but I can give you all some sneak peak images we're looking to put up to show these dies off and how they work.
If you have other questions on them give a shout. I'll try to dig up more pictures.
WM