It was a blind alley in large-bore ordnance development. Is there any reason to think it would be better in smaller bores?
I think artillery shells have a copper ring around them that engage the rifling in the bore. I don't believe the artillery shell is actually deformed in the barrel of the artillery piece, just this copper ring is distorted.
A bullet when fired leaves the case and travels the free bore (hopefully some what straight) with a large amount of blow-by until it hits the lands of the rifling. When it hits the rifling it is deformed considerable, hopefully in a some what concentric and repeatable manner. Then the bullet travels down the rifle barrel which imparts a spin. The initial blow by of hot burning powder and gasses is going to heat the throat of the barrel. The friction of the bullet hitting and deforming is going to impart even more heat to the barrel. This heat and friction is what I believe is a major cause of barrel erosion.
Yes, I do seat my bullets for my target rifles long so they are just shy of contacting the lands. Yes this does seem to make a more accurate load by what I believe is the bullet hitting the lands in a more consistent manner and conforming to the rifling in a more repeatable way making the flight characteristics more uniform from bullet to bullet and help the bullets hit the target in a more consistent spot.
To me it stands to reason that a bullet that doesn't have any freebore, minimal to no deformation and almost no blow by will be more consistent in the bore of the rifle and after it leaves the barrel???? It also stands to reason, to me at least, that less deformation and less friction will result in a faster bullet from the same charge. I understand that when I seat my bullets long for my target loads that this will cause a higher chamber pressure. A hex bullet having no free bore and no blow-by seems like it would also translate to even higher pressures... so less powder would be used or a slower powder would be used to compensate. No blow-by or a more consistent minimal blow-by would also eliminate or reduce one variable in the ballistics of a bullet resulting in a more consistent bullet velocity and hence bullet path after it leaves the barrel.
To sum it up, my theory is a hex shaped bullet initially aligned in a hex shaped bore by a hex shaped case will be more accurate, capable of higher velocities, cause less barrel heat (and less barrel distortion from heat) and reduce throat erosion in my expensive target barrels.
This is just my theory so take it for what you will... but remember... you asked!
P.S. I have also considered steel cased cartridges ( an inch plus in diameter with VERY thick walls ) aligned to a chamber-less barrel via a hex recess in the breach of the barrel in which the hex tit on the end of the case aligns. The cartridge would be mounted to the barrel with a threaded retainer that goes over a shoulder cut on the external of the case then threads over external threading on the breach of the barrel. Not only would this eliminate the inconsistencies of a brass case from the ballistic equation but it would also allow the steel cases to be precision machined to very tight tolerances. What I would really love about a setup like this is the vast number of internal cartridge geometries that could be tested with a single barrel without having to cut custom chambers in the barrel. But, again, just more theorizing... take it for what it is worth.
OK, maybe there are no great leaps of improvement to be made here... but I would be ecstatic with a couple millimeters of improvement!
Would you like to ask me how I would make barrels more accurate?
