7.62x54r with .308 bullets vs Soviet factory ammo Целевые патроны and Экстра

[PMB27]

Herewith please find the result of my recent, very short but informative trip to the shooting range.
I shot only 12 rounds - 6 of them were factory ammunition ( the cartridges are already well over 50 years old, but they are still very good - Целевые патроны and Экстра ) and 6 were prepared and reloaded by me. [ case: S&B, primer: boxer – Fiocchi LR, gunpowder – Lovex 73.6 – 45.25 gr].
I wanted to see if I could replace the old factory Soviet ammo with new reloading ammo.
I did not change the sight settings - scope : POSP 4-12x42, reticle no. 10, weapon on bipod, sitting shooting position, distance 100m.
The 3-shots groups may be too small - it would be better to shoot 5 rounds groups, but I only prepared 3 reloaded rounds of each type, with two different bullets - based only on GRT calculations with an assumption of -15% of maximum pressure.
The .308 bullets performed very well – so it might be true that Soviet sport high precision barrels had 7,82 mm diameter instead of 7,92 mm like the military barrels - that claim about the difference in calibers of military and sports weapons for 7.62x54r ammunition from Ruslan Chumak's book is, however, strongly contested on the Russian firearms forums.
Anyway with the Lapua Scenar-L 175gr. – if I further clarify the weight of gunpowder with the proper “ladder”, I should receive an excellent replacement for the old Soviet ammunition.

And the rifle - МЦ-13 [ MC-13 aka Mts-13 ]