Hardest/most elaborate case conversion you did?

[challenger_i]

Making a rimmed version of the 6.5 TCU from 5.6x50R. 1st trick is finding the parent brass!
Anneal, FLS in a Hornady die (decapping/expanding stem removed), trim to 46mm, fire-form in a chamber insert made for 410 scatter gun (hey! I had a special chamber reamer made for this "non-standard caliber: may as well get some use out of it!), neck ream the case while seated in the sizing die (had my gun doctor make a reaming tool to fit the Hornady die: works like a champ!), Fire-form again. Load, go punch paper.
Is TRULY a labor of love, and I am pleased I have 200rnds completed, so as I NEVER have to do THAT, again!

[Good Cheer]

Recently found a long ago bunch of formed, annealed, turned .308's that I'd made out of .270 Winchester for precise necks.
Hardly a tough or elaborate conversion job but hey OK it was fun.

[Ben_51004]

Old thread, but good stuff here! I've done .40-65 from .45-70, that one's a no brainer. Slightly more challenging was .221 Fireball from .223 Rem. Pretty easy with C&H forming dies. Currently making .219 Zipper from 30-30 Win. Form #1, Form #2, file trim, FL size, expander die, final trim on Forrester trimmer, then neck turn. That's the most involved conversion I've done, but it's working.

[barryjyoung]

I convert 30-30, .219 Zipper, and a few other cases into two different .219 Donaldson Wasp cases. One of the chambers is longer than the other. This also requires reaming and turning the case neck after three dies to neck it down and push the shoulder back. I also make 6 Dasher from 6BR using a Whidden hydroforming (pain in the butt) die. I suppose I could just fireform, but at the price of components, that is no longer the simple fix it once was.

[15meter]

Stumbled across this old thread while looking for something else, figured I'd drag it back to the top of the pile to see if any body else has case conversion horror stories.

[lightman]

Probably making 357 Herrett cases from 30-30 cases. Not that hard but more than simply resizing and trimming.

[moosehunt]

.404 Jeffery cases from .300 RUM. The necks come out .010 to .015 short, but they work fine. Obviously .375 RUM would be a better starting point, but those are hard to come by.

[steveu]

280 Ross from 300WM without a set of 280 Ross dies.

[Randy Bohannon]

40-50 SBN (Sharps Bottleneck) found a set of RCBS Forming dies on EBay and bought a set of CH4D dies to use 45-70 brass. I’ve been advised that Winchester brass is the ticket for the 40-50 SBN reforming for the Shiloh rifles.
I bought 20 pieces of 40-50 SBN from a company called Ammunition Artifacts it’s Starline brass. Trim length is 1.775” so I bought a jewelers saw and use the RCBS forming die and a washer to trim near final length then final length on my Forster trimmer. This is a much overlooked cartridge, the smallish cartridge lends itself to smokeless powder quite nicely and the form die isn’t really needed as the CH4D dies will form the brass even without annealing but annealing is required for B/P.
I’m hoping Shiloh starts my rifle this year I ordered it 25 months ago. It will be the only Military Carbine chambered for the venerable 40-50 SBN that Shiloh has done.

[RJTyler]

1) 30-30 Winchester to 30 Remington

2) 300 Winchester Magnum to .410 shotshell