I was thinking about the 458 Lott, and how alot of the bullet shank is in the case with a 500 gr bullet. In that case, you'd have a long sub-caliber shank, and I'd be concerned about yawing. If you just have a short sub caliber nub at the base, then you have a really long COL.

It makes alot more sense with your followup post. Certainly a different way to skin the cat so to speak.

Paul -

I don't get the gas sealing comments, as boat tails work fine and hold world records for accuracy. We don't need more shank than that of a long boat tail to get a very strong grip on a solid shank using a Lee Factory crimp die to mandrel the case mouth into a nice deep cannelure. Heck, we could use a boat tail type shank and cover it with a neck diameter "shank sabot" to get a tight fit in the neck that could even expand to seal gas.

The key would be a seperate base that securely mounts on a precision drilled flat base or boat tailed bullet. The BASES are what I would sell. The flat baed type would have a tapered boat tail that stays with the bullet...probably steel, and a small sabot that sheds when the bullet exits the bore. The leading edge of the steel base would have the cannelure cut into it.

So, picture your 475/458 as a .475 base with a .500 or .510 bullet mounted on it. Only the saboted steel base goes into the case mouth. Now you have a case that holds at least 90 grs of water behind a .510 bullet. If the bullet is 1.1 inches long, you have COL 3.60. This combo will yeild 7350 FPE and 2572 fps with a 500 grainer.

A 450 Marlin case would hold 65 grs of water, and deliver 6060 fpe at COL 3.4 with a bullet 1.3 inches in length. This would fit into an '06 length action. This could be a 600 gr .510 at 2150 fps.

Anyway the idea is to go .025 to .035 bigger than the largest diameter a case can take, and cut the throat close to bullet diameter.

It certainly would be wildcatting. The rub is, it is very difficult to load and properly crimp such ammo. Also, the 22 rf bullets are soft, with a heeled base that expands to bore dia to create a proper seal. I'd be concerned that a relatively long bullet base much smaller than bore dia might create inacuracy.

It basically comes down to effort and cost. It is relatively easy to blow out a 458 Lott case to 470 capstic, and their are plenty of .475" bullets available. It would be much more work and expense to make custom bullets, and special re-loading dies.

Wildcatters generally take the easiest cheapest approach to the desired results. Ie, no custom bullets, and relatively straightforward dies.

Now if you stuck with soft cast bullets, you could easily have a mold made at minimal expense. Not sure what you'd do about the dies though.

What if we rebate the base of a bullet to fit inner neck diameter, and leave the rest of the bearing surface larger to match the outside diameter of the case? This is essentially what most 22 rimfires do.

For example, a 458 Win or a 458 Lott case could launch a .475 bullet into a .475 bore. We are not changing the case, just the chamber and bore.

A 44 Mag could launch .458 bullets, and a 480 Ruger .500s.

COLs would be longer, because of shallow seating, but case capacity would go up. The rebated base could be solid, with a good crimp channel facing off squarely on the case mouth. The bullet would align itself with the bore.


Heck, 22s are super accurate, so why not?

funny, that's how craig b published some pics of a 375 to 458 lott. about the only case where the round would seal the chamber


1: it WOULD NOT seal the chamber in a 475 on a 458 case, that is, if you could feed from the breech

2: no real benefit of testing the gas handling of your action

jeffe