This is the 223 Short V1 Final Design from which we are getting a production chamber reamer made. Also getting a die reamer made if we need that too. I will send the chamber reamer to Larry so he can chamber the slow twist barrel (1:12 I think) he has had hanging about for the best part of a year.
I will match the barrel up with a Steven's rifle, also part of our "poor man's" design goals. At some stage after we complete development, I will get a Savage short action with Accutrigger and Accustock, just to see what we can squeeze out of the Short in the 35g to 46g bullet range. I am counting on the Short not to be a barrel burner as we use only as much powder as a 22 Hornet.
As we made all our brass to date from different head stamps, the outside neck diameter ranges from .256 using 221 FB brass to .258, .2605 to .261 using other types. We had to settle on the largest neck OD to meet our design goal of catering to those folks who pick up range brass or use mil. surp. and want to make 223 Short cases themselves - yep, this is a poor man's wildcat, that is for sure.
Also, once the form & trim die is cut down and reamed, as soon as I get my first batch of 223 Shorts completed, I will get 100 x 22 Rem Jet cases from PRVI (they are cheap and a lot easier to form than 357 Mag cases) and use the same dies to form the 223 Short Rimmed cases. It'll look like the 218 Bee but dimensions will be quite different. We will have to get another reamer made to account for the rim recess, so my thinking is that will come in the new year.
I already have our first volunteer tester lined up for the rimmed version, in a converted Martini that was re-barelled for the 22 LR way back when. They kept the same action as the 303 British it was originally designed for. A few posts back you can see the bolt face thrust calculations we used to determine that the 22 Short Rimmed will be safe in the old rifle.

I appreciate your continued interest in the project, and look forward to being able to post the final development figures, and then continue the thread with folks that want to try the short themselves and want to report back to the thread. The beauty of trying the short using a barrel blank chambered to size, is that if you don't like it, your barrel can be rechambered to a 221 FB or 222 Rem or 223 Rem etc. This makes it a very safe wildcat to explore.
We will also get a number of extra form and trim dies modified for the Short if folks don't want to modify their own dies. The reamers will be available for rent thru GBO H&R Forum, and I may send a couple to Clymer's so they have them on hand as well.
I have got over any feelings of proprietorship in the design. I feel honored that after I designed it, other GBO members took up the challenge to get it well and truly prototyped and tested. It is a testament to the people you find at GBO.
We have had a good time developing this on a shoestring, and I hope as many folks as possible want to give it a try, the more the merrier. I'll be producing 223 Short brass for sale on a hobby basis, made from once fired brass, and I will be able to sell it for $7.50/25, $12.50/50 and $20.00/100 plus shipping. Remember when all brass was priced like that?
Stay tuned - the same Bat Time and the same Bat Channel...
I wish you all a Happy and Safe Thanksgiving.