A couple of points:
It seems to me that the main advantage of the Forster press it that it allows the case and die to float, so that they can line up with each other as a case is inserted into a die. This can be accomplished to some extent, with a Rock Chucker by using a Lee lock ring set for just enough compression to keep the die from turning. I take this one step further by locking the Lee ring to the die with a Hornady ring above it that is turned down to make contact with the Lee and then tightened. This locks the Lee on the die because the V thread of the Hornady thickens the ring slightly as it is tightened, Locking the Lees position on the die.
I am always fine tuning FL dies for a exact amount of shoulder bump. This varies with each batch of brass, and I verify the setting for each, and at the beginning of each loading session. I have a friend that has a couple of Forster presses, and I must say that once they are set, they are fine, but really no easier or faster than my Rock Chucker or Harrell presses. They are at a disadvantage when setting bump. It is not as handy as varying the compression of a Lee lock rings O ring in a threaded press. The other area that I do not like them for is when I am expanding up .220 Russian brass to 6mm when I am making 6PPC brass. Over the years I have tested and written about several concentricity gauges, and own four different gauges, so I use my favorite on quite a bit to check how equipment is working. The floating feature of the Forster press is a positive disadvantage when using a expander die to open up cases to a larger caliber. The Rock Chucker is better, and my Harrell Combo press is the best that I have tried. It has very straight alignment, due to the way that it is made, and because it has no thread adapter, and the die threads are as tight as they could practically be. There are differences in these presses for this task that are readily seen with a concentricity gauge. The Rock Chucker is acceptable, the Harrell is better, and I would prefer not to use the Forster for this operation. On the other hand, once the Forster is set up, it is a smooth operating machine that functions well. Another poster mentioned that he likes the positive stop priming on the Forster press. Everyone that I know of that shoots short range benchrest seats primers by feel, using a hand tool. Primers are of different thicknesses and even if primer pockets have been cut to uniform depths, if primers are to be seated to uniform slight compression beyond bottoming, they will be at different depths. As far as top of press priming goes, having used both, I prefer the RCBS setup that screws in like a die. With proper adjustment, it gives really good feel, but it is not for the ham fisted, or someone who is oblivious to differences in setup. Like another poster, I use an arbor press type seater for my most critical work, and have even taken that a bit farther with a Nielson seater that is a much better fit on my cases. Seaters can preserve or degrade what the sizer has produced. They cannot improve it. Bottom line, it is the dies that are the most important thing. You can use an ill fitting set of dies in the best press in the world, and a fellow that has a perfect set of dies for his chamber, will produce better results on the cheapest worn out press that will accomplish shoving the cases into the die to a given depth. I wish that I could find a picture that I once saw of Tony Boyer's range loading setup. I believe that he uses an old, cast iron RCBS Jr. press, and he seems to have done pretty well with it. When I first set out to have a 6PPC built, I bought the best reamer that I could find, knowing that I would be using more than one barrel and that I wanted my reloading dies to maintain the same fit with my brass. By owning the reamer, and because the person that chambers my barrels has done such fine work, I can interchange any of my brass, no matter what barrel it has been fired in.
-Axial ammo is straighter or more concentric.
