Thinking about doing a one off wildcat...how?

The long neck and the ability to seat long 180-190gr bullets with the base of the bullet at the shoulder neck junction is what I would like to achieve. Since the boat tail on these bullets range from .2-.25 the only way to configure like this is to put a freakishly long .5 neck on it. If anyone wants to learn the internal ballistic theory that relates to this design do a search on the 6.5/60smc.

c-fbmi, How would it work if I started with a RUM case cut off at the mid point of the shoulder? It wouldn't be pushing a shoulder back, instead it would be creating a fresh one. This would eliminate the 5 stage trip through the dies no?
 
Negative, you end up folding the case in on itself. This does give you a uniform neck thickness but it still must be reduced along the way. You would still need 4-5 steps to do this. If you already have lots of die sets you can try this. Run a RUM case shoulder and upper body into the base of a 30-06 die for about 1/2". LOTS OF CASE LUBE !!!! Now run that same 1/2" up into the base of a 30-30 die, then up into a 223 die. I have done a lot of this to design different cases, 44 mag carbides work well for sizing down case bodies and moving shoulders back a long ways as do 45 Colt, 41 Mag and 357 Mag carbide dies. From here you could go into a 325 WSM and then the 7 WSM. Be inventive, start with scrap RUM cases until you get a procedure that works. I have about 400 RUM cases that are scrap due to loose primer pockets, this is exactly why I don't discard them. All you really need is a hunk of brass that goes into the chamber, headspaces correctly, and the bolt closes..........60,000 psi will do the rest for you. If this were my project, I would run the cases down as described, roughly, and get them to a point where they would chamber, load them up with cheap 277 bullets and fireform to dimension THEN outside neck turn to the neck thickness I desired.
Go buy a stuck case remover before starting this endeavor !! Oh ya, and always remove the expander ball assy when using dies for case forming, trust me it's way easier than the alternative when you do stick a case.
 
I got up early this morning still thinking about this so I decided to try a scaled down version of the RUM resizing. I started with a .270 win and sized to 7mm-08 in one step, I used the torch lots and I ended up with a case that worked on my second try. I'm not saying that it will go the same with the bigger casa and 35' shoulders but it did give me confidence that it can be done. I have quite a few die sets so I'll take your advice and start practicing with whatever I can just to gain some much needed experience.

Oh and yes I do have a stuck case remover...been there done that wrecked some dies...dont want that lesson again.
 
Ok so I've now been trying to shape the RUM cases down. I put them into a .257 weatherby die followed by a .270 win then into .243, just to reduce diameter at the shoulder. What's happening when I then try to push the shoulders back is the case collapses vertically. I've tried heat and and I've tried cutting the case back half way through the shoulder before starting, all with the same result. I've even had them collapse just trying to neck them down in a 7mm wsm die. 300 RUM Remington brass by the way.

Anyone have any ideas I could try, I only have 40 cases left to experiment on so.....
 
cdn shooter said:
c-fbmi, thanks for the insight, It's really good to hear the truth from people who have been there done that. This design that I'm chasing is all about internal ballistics, I realize that there are many other choices that I could use to achieve what this wildcat would do in the external ballistic department, I won't argue that. I do however believe that there are still gains to be made in improving powder burn consistency aka accuracy, and barrel life. There's some interesting research going on on this subject and I think that designs like this will gain popularity over the next few years, or not, who knows.

If you dont mind I would like to pick your brain for more wisdom. What case would you say would make the transition to what I want the easiest? My only real needs are, 2x caliber neck length, .284 projectile, short fat case in the 55-65gr volume range. I just thought saum because it is closest to the finish product, but with comments on brass I'm leaning towards WSM although I would have to push the shoulders back further. Would the .270 version work better ie. less brass buildup. Honestly if I could have anything I wanted I would tack on .28 to the neck of a 7WSM and be done, not many ways of doing that though from what I can tell.
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300 WSM case sized in the 7 SAUM die. That would get rid of the WSM's 40 degree shoulder and leave a long neck. The neck would end up close to 2 calibers long. This requires precise annealing. If case neck and shoulder get too soft shoulders will collapse when resizing. When necking down WSM brass I don't go past 450 degrees F. Neck thickness varies quite a bit on W-W WSM brass and thickness changes from neck to shoulder. Outside neck turning with a fluted pilot system (K M) will do the best job. Now comes the risky part, load development. WSM brass has some weird expansion traits. I measure diameter of case just above extractor groove and diameter of extractor groove before and after firing. I have seen extractor groove expand up to 0.005". I live out of town so I can load and fire to establish max loads in a semi-controlled manner. I have a Benchmark annealing machine and use "Markall" temp indicator pens to adjust timer for correct temp. This last weekend I made 300 6.5-300 WSM brass without losing a cartridge.
 
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