Wasn't a question of a "nay-sayer", I was just looking to get educated. When I read that the bore in a 22HP could be .223" and still be within mfr'ing specs, I started wondering if .224's would even get enough grip to stabilize well. Which fits into the whole "undersized" bullets thing.
But as to the throat.. I didn't think bullets should ever seal the throat in any gun. That happens which it hits the lands. So does it matter if there is 0.002" clearance between the side of the bullet and the side of the throat vs 0.005"? If anything I'd think the increased space would serve to slow down the gas's rush forward rather than make it worse (though that "slowing down" would be minuscule).
Would happily trade a couple of the programming languages I've learned over the years for some engineering knowledge.
If you have or can get Ken Waters' Pet Loads with his 1983 findings on the 22 Imp, its pretty interesting. I think his biggest issue is the often seen, old school "need" of full length re-sizing. The aforementioned mis-match of stable bullets, die and brass (and bullet) discrepancies along with re-shaping the fired cases to resemble his die and not so much the chamber all caused havoc. Granted he was using a lever gun, but partial re-sizing can be done so in these arms without having chambering issues.
You will find he had very good success with the 63 Sierra and 70 Speer semi-points, both .224. A simple change out of the expander ball should improve accuracy a bit if using the smaller diameter bullets. Both were simple jacketed, nearly pure lead cored, flat based bullets that would obturate a bit. As a note, his gun detested sleek 70 grain .227's and even the 60grain Hornady .224. This is where the twist and bullet shape failed.
I can tell you a seal in the throat, especially with a bullet similar in shape and diameter to the throat, greatly helps accuracy. Cast bullet shooters and benchrest shooters alike try to make case necks and the bullets used fit as tightly as possible, without creating pressure or function issues. Primarily its to eliminate tipping, but in the case with cast bullets its to provide support from bullet imbalance and seal from case mouth all the way to the muzzle crown. If we don't have this seal with cast in a revolver throat will will have leading and accuracy issues. With jacketed bullets, we will see forcing cone erosion increase.
Most benchrest bullets incorporate a groove diameter seal, or pressure ring, at the bullet base; the neck, throat and leade are cut to be used with specific bullets to cut down on tipping, match each other to create a seal from case mouth to muzzle crown along with eliminating re-sizing of the cartridge upon being reloaded.
