Akinswi said:
I have one. They are fine, though they do raise the shell holding system up, lessening the height of the tallest cartridge or the highest part of a die you can fit in the press and still have the yoke clear the top of the die. Your Co-ax is newer than mine, and I believe they have increased the yoke clearance a bit since I got mine, but I don't believe I can use my 30-06 Redding Competition Seater Die in mine with the shell holder adapter in place because it will interfere with the yoke, though it might work on yours. Also, the adapter won't solve your problem unless you grind 0.004" off the top of your conventional shell holder's deck. The Forster shell holder plates are precision ground to the same exact 1/8" thickness from the bottom surface they share with the case head as the standard shell holder's deck height has above the surface the case rests on. This had to be done to keep standard dies usable in the press. The one thing that is easier with conventional shell holders is sliding a 0.004" feeler gauge in under the case from the front. Again, you have to remove your decapping pin to do this or else, as mentioned earlier, cut a slot in the gauge (Dremel abrasive wheel can cut the hardened gauge steel) or put a hole in it (carbide drill or small grinding point).
Odds and ends:
A common reason to control the shoulder height of either a rimmed or belted case is to be able to headspace on the shoulder instead of the rim. Rim headspace ranges from 0.000 to 0.017 in the 30-30, and the sizing of the shoulder clearance is a minimum of 0.0173" (so the shoulder contact can't interfere with the rim making headspace contact forward against the rim recess in the chamber) to 0.0473" when the chamber shoulder is at maximum, and the cartridge case shoulder is at factory minimum. That's a lot of brass movement, and it will shorten case life. Headspacing on the shoulder greatly reduces the amount of case stretching that goes on and will increase case life significantly. It can also improve accuracy by having the taper of the shoulder center the neck and bullet in the throat during firing, whereas headspacing on the rim allows rim bends or other imperfections to influence what side of the throat the neck and bullet favor.
For the above reasons, plus the tendency of military chambers to be a bit loose, a lot of 3.3 British users slip an o-ring over their cases so the rim squashes it against the headspace surface in the rim recess. This holds the case back against the breech face during firing to form the shoulder forward so they can resize to headspace on the shoulder afterward.
Regarding Shoulder Bump
This is a term that has gradually come to be misused. I first heard it in the late 1980s or the early 1990s in Precision Shooting magazine. It referred to a system of resizing in which the height of the shoulder above the case head was formed lower without narrowing the sides of the case at all. In other words, it referred to shoulder-only resizing. It was used in custom rifles for which the gunsmith had taken the die blank and used the same reamer he cut the rifle's chamber with to cut the die profile. This would not size a neck down unless you cut the neck for bushings or resized the neck separately, both of which were done at times. However, most custom rifles of this sort only had half a thousandth or less of neck clearance anyway, so neck size changed very little, and you could still load and shoot using one without messing with the neck any more than a Lee Loader messes with the neck.
If you think about the geometry of a case blown out to fit the chamber, you will realize that if there is any taper to the case, "bumping" the shoulder back with this chamber-size die will actually slightly touch the sides of the case if they are expanded to full chamber diameter. And if you use a case enough times at high enough pressure, you will eventually get there. But not initially. And a 30-30 isn't running at very high rifle pressure, so, due to spring-back, the sides would be unlike to be resized at all.
Today, Forster sells their Bushing Bump Die, which is a die that resizes the neck with a bushing but is chamber diameter below the shoulder and thus "bumps" the shoulder in the original meaning. But for whatever reason, "shoulder bumping" has come to be used to refer to partially resizing the whole case just far enough so you see the head-to-shoulder length reduced a little. This was called partial resizing at one point, but "partial-resizing" is also used to describe putting a case just far enough into the die to resize most of the neck, but not enough to touch the shoulder at all, which is basically a form of neck-sizing-only, but is differentiated by leaving enough (the last 1/8" or so) of the neck fat to help center the bullet in the throat. So this business of crossing terms over to mean a couple of different things is not new.
