I am thinking about doing a wildcat on the .284 case, but not 2.17". I'd like to get some "basic" say around 2.5". The 9.3X64 isn't really an option for me because the rim is larger than standard Mauser. I'd like to slightly improve it to about .485" at the shoulder. I'm guessing about .423/.425" is the max bullet diameter I could go with good headspace and staying with a fairly normal/available bullets. Shoulder angle will most likely be 45 degrees.
The main goal here is to stay with the standard length (long) action and a standard bolt face with the largest feasable bore size. Loosing 1 round of mag capacity is not a concern. Any ideas or suggestions from the "old salts" would be appreciated. Also, am I doing something that has basicly been done?

10.75x68
Maybe shorten it a tad

I aggree with Boom.
If you absoulutely want .473" boltface, anybody with a lathe can reduce diameter on rim very fast. Make an improoved shoulder, cut case to 2,5"(For better use of 400 grs bullets) and Voila, you have your own cat.

If you really can get 2,5" basic .284 brass, that is of course easier, but I think the rebate would be larger, giving more hazle with feeding.

O.K. The "bible" so to speak is in two volumes by Mr. P.O. Ackley... he covers thousands of cartridges from the beginnings of smokeless to about 1985 when he retired. 7Rem Mag? Yes. PPC's? No. Books available from eabco.com, Sinclairinternational.com, ebay sometimes, amazon, etc. There are other books too.

.284 was sold as a case of .30/'06 capacity but short enough to work thru a short action with 7mm bullets. Yes, you give up one round magazine capacity. The sharp shoulder and short, fat powder column had been proven by experimenters over decades. O.K. What has been done with the /'06 case? .333 OKH. .35 Whelan. .375 Whelan. I think there was a .400 Whelan that did not work well for lack of shoulder... Some faulted the .35 and an improved with distinct shoulder, the "Brown-Whelan" was available.

Now you want to take the newer and slightly bigger around case of the .284 and ??? I wonder if you should enlarge the shoulder...??? Too straight and extraction might not. I will defer to the more trained machinists. .40 should work fine. .41 maybe. .42 might be pushing. If you add a shoulder...

None of this is going to be free. I would be more inclined to work with a short belted case or even rimmed for certain headspace... .450 Marlin? .444 Marlin? but about anything can be done with enough $$$ luck

Thanks for the input guys. I just have this "thing" about belts. Maybe some day I will build a .470 Capstick off this 77 Ruger doner action and a belt would be OK then. I'm guessing that if JD Jones and others can do .416 on an improved '06 case, then .425 should work on an improved .284 case. Basically I want the .416-284 Barnes with a bigger diameter bullet and 2.5" versus 2.17" A while back someone on here said .284 basic was being done by someone.
I have a Rem 700, 1903 Springfield and 1917 Enfield doner actions. I would really rather not booger up the bolt face on any of them. Although, the 1917 did come with 2 bolts, so I could ream one out and keep the other in reserve in the event I ever wanted to change it in the future.
If 284 basic brass is atainable, I would like to do all 3 of the above actions on that brass in diameters .308, .358, and .423. Kind of beltless magnums on mauser bolt faces.

Don't forget that the 416 JDJ's are on rimmed (444 marlin I believe) cases so the miniscule shoulders are not as big of a factor. I know he also uses 06 cases, but again, they're made for single shot rifles, less head space problems vs a repeater.

I had pondered a .411 in a .284 case, that could be quite interesting.

Depending on how much you want to rebate, there is also the option of using 425 westley richards brass, those cases are very fat, but the rebate is quite extreme.