I note that the older rifle bullet is a true Minie type.
This would really aid obturation (expansion to seal the bore completely) in a rifle with an iffy barrel.
It would have more base drag than a flat-base bullet but, at normal combat ranges of 500 yards/metres and under, that would make little difference. It was a really good idea and I am surprised that Russia seems to have been the only country to do it on any scale. Has anyone taken apart any of the older FINNISH ammunition to see if it conforms to this idea?
My late friend Gavin Tait had a project which went over 20 years, of seeing just HOW well he could make various old military rifles shoot. We worked together on perhaps 40 or 50 rifles over the years, all military types, and there were very few that we could not coax 1 MOA from. With very careful bedding and handloading, there is no reason that a military rifle will not shoot, and, when you are getting honest 1-MOA groups out of a century-old barrel, you tend to develop a good bit of respect for the men and women who made the things.
In our testing we worked with several Moisin-Nagant rifles, including a Finned 1907 Sestroryetsk, a Finned 1906 Tulskiy, a Finnish Dragoon Rifle and several 91/30 rifles dating between 1937 and 1943. Of the rifles we tested, ONE only had to be discarded: it had been misrepresented at time of sale and the advertised "pristine" bore was terribly pitted, to the point that it simply ripped the jackets to shreds and would NOT make better than a 10-inch group at 100 yards. ALL of the others, even century-old rifles with counterbored barrels, we could make shoot fairly well; by Gavin's standards, this meant 2 MOA or less. One thing we found is that they ALL would shoot their best with bullets in the .311 to .312 diameter range. Trying .308 bullets, as recommended in the US manuals, was a dead bust in every rifle: hopeless. But we also found that a "hopeless" rifle, when fed .312" slugs, suddenly would become an obedient pup and sit up and do tricks.
Boat-tailed bullets originally were developed to give longer ranges of suppressive or covering fire WITH MACHINE GUNS. This is a point that most people miss.
Sticking with flat-base bullets, you can make MOST older military rifles shoot their best, especially when the flat-based bullet is allied with a quicker powder. This combination will give best obturation almost every time. For normal hunting/combat ranges, this is more than sufficient.
Hope this helps.