Can very truthfully state that 99+% of my PM's (individual communications here on iKC) are with 3 individuals .. JJ, Jan, & John Bamford. I too take my privacy VERY seriously.
Re: Your possible project using 5.56 casing ends. I believe the most economical approach would be for you to fabricate the wooden clamping fixtures out of existing wood scrap that you've left over from previous projects that would ultimately end up working with your existing metal drill press vise.
It would be far easier & more economical to simply make inserts that would fit in your existing drill press vise !!!
However .. should you decide upon purchasing any of the listed items .. I highly suggest that you install metal "through rods" at the corners. This will greatly enhance the structural integrity of the vise. I am not a carpenter ..so.. I do not know the proper terminology used in designating the size of nails. Regardless .. choose a nail that is equal to or slightly exceeds the height of the vise & trim it such that its length is equal to the height of the vise. Then drill a hole @ each corner (equidistant from the edges, i.e. center the hole in the corners) that is ever so slightly larger than the chosen nail size. Such that the nail just drops in the hole. OR, simply chose whatever nail size you have on hand and can trim to the required length (equal to the height of the vise).
Then .. fill the hole with a good quality wood glue .. Elmers or Gorrilla or any good quality liquid adhesive that you have on hand. Then .. slide the the pre-trimmed metal pin into said hole & let cure overnight.
The addition of a metal through pin @ the corners will greatly enhance the structural integrity of the vise. Mine came with them already installed. Not all do.
NOTE: The unit I have measures 126mm X 96mm X 54mm ..&.. I originally pd $14.24 for it back in June of 2015. Prices (for that size) have increased dramatically in the last couple years .. they are now priced in the mid $20 range. The options I’ve listed below are slightly smaller ..but.. should be adequate for the purpose. Do keep in mind .. these are NOT metal machinist vises. They are intended for lighter duty. However .. mine has held up well & I’ve found it quite useful. You may have seen it pictured in a # of my projects in the Repair & Mod group. AND .. for the prices of the ones I’ve attached links for .. I doubt you could fabricate one. However .. if you’ve already a vise for your drill press .. the wooden clamps themselves are quite easy to fabricate & can usually be accomplished using “scrap” wood you’ve accumulated from previous projects.
Do be aware ..for the units I’ve listed below.. average shipping time is about 20 days. However .. the quoted price is “delivered in your mailbox” !!!
Might I suggest .. when it comes to your spent cartridge project .. you fabricate a holding fixture similar to what I've pictured below. I've found it quite handy when securing / holding round objects without causing damage to said round object.
The unit with the square hole was supplied with my little wooden vise.
I fabricated the unit with the 2 round holes for a project of my own design.
These holding / clamping devices are easily fabricated by generating 2 similar boards.
Clamping them in a vise ..&.. then drilling a hole of the appropriate diameter
that is centered on the joining line of the 2 wooden pieces.
I further suggest the the drilled hole be ever so slightly smaller in diameter that the piece that you intend to clamp therein ..as.. the wood will compress far more easily than the metal & therefor very effectively clamp / hold the metal work-piece in place.