So, we got three votes for what is basically a copy of what the enemy did their first turn and two for something to try to surpass them, plus the usual vote or three for random stuff. Joy.
I definitely understand where you're coming from - you see the Long-Range Rifle Mk. I as primarily a copy of the Samara, and see that their use has not helped Atterton against the Victoria Air Rifle and that, therefore, the Long-Range Rifle Mk. I will not help us in the land war. Additionally, you see it as not giving us much new technology to build upon.
From my view, the Long-Range Rifle Mk. I is not simply a copy of the Samara Rifle - where the Samara had been a shortened adaption of the Brown Bess, the Mk. I is a completely new design. This means, in comparison, a higher effective range - probably double or more, a higher reload speed thanks to the Minié Ball, and it will be cheaper than the Victoria Rifle.
Looking at the different designs, the Victoria is able to fire fifteen shots in about thirty seconds to a minute, to an effective distance of 50-100 meters. The Samara, with an effective range of about 100-150m is going to be able to fire one shot every thirty to sixty seconds. The projected Mk. I rifle will be able to effectively fire at a range of 300m, probably slightly faster than the Samara.
Therefore, where the Samara allows the enemy to close the fifty meter range difference in a few seconds, they'd have to run two hundred meters to get into range - a rather more daunting proposal.
In effect, while I think that it'll provide less new tech than the alternatives, it provides us with an immediately useable weapon for our skirmishers, and later (once cheap, maybe even immediately with our ore?) even for our mainline infantry.