Short COAL has a couple of attractions:
1. Xtreme bullets have a poor excuse for a canneleur. Neck tension seems good (even longer seated bullets took three whacks to pull) and crimp jump not really a concern, but crimping over the shoulder means no worry about breaking the plating. This is a *very* minor benefit.
I agree......very minor, if at all. While the cannelure may be a poor excuse, is it, or even crimping over the shoulder needed at the pressures you are looking to achieve, when neck tension alone is as good as you claim? Seems to me that crimping over the shoulder would result in over working the brass and lead to shortened brass life, as opposed to lightly crimping in the "poor excuse" cannelure.
2. Shorter case volume and higher % fill should (?) minimize powder positional variation. Even with much faster burning powders, I've seen some pretty dramatic differences over the chrono powder-forward vs powder-back. Hard to believe that couldn't affect POI at longer ranges, at least off a rest. (Standing on my hind legs, we have much larger problems to worry about, but best to fix what can be fixed.)
From everything I have read over the years, Longshot is not position sensitive at all, at the levels you are loading. Thus there is very little, if any, reason to seat the bullet deeper in the case than intended. Either use a tad more powder and seat to the cannelure in .44 mag cases, or if you insist on reloading .44 special, trim your brass to .44 special length, or obtain some .44 special brass and crimp on the cannelure.
3. Longshot is known to "prefer" fairly high pressure (relative to standard-pressure Specials). I have a lot of it, and it seems quite suitable for the velocities I'm interested in if a modest charge can be made to burn cleanly and consistently. I've read multiple accounts of it "cleaning up" at pressures well below the normal operating range of .44 Magnum, so I expect that the desired burn quality and velocity will come at a sane pressure. If I'm not seeing the accuracy I hope for at 50 yards once the burn cleans up, I'm not going to keep pushing the charges up hoping for some revelation.
I put very little into what constitutes "clean burning" when it comes to accuracy. I have some soft plinking loads with Unique that are dirty as Hades, but extremely accurate. That said, if I'm looking for a extremely accurate load for .44 past 50 yards, odds are I'm not looking at getting it with a plated bullet.
*If I find a truly good load, I might later splurge on Nosler 240 JHPs, but by my measurements the shank would be the same depth into the case, so I hope/expect that will perturb the load minimally.
Which have a great cannelure and are extremely accurate. Again, no legitimate(IMHO) reason to crimp over the shoulder, by seating to .44 special OAL using .44 mag brass. Use them as intended.
