Historically after the experience of the Spanish American war the US military realized it needed to upgrade it's existing rifles and ammunition to match the firepower of the new European rifles, as their .30-40 Krag's couldn't match the Spanish Mausers they encountered. That led to the .30-03 and shortly thereafter the .30-06. But what if they instead decided 'if you can't beat 'em, join 'em' and adopted an equivalent to the 7mm Mauser cartridge? Now I get that 7mm Mauser and the rifle won't likely be something they adopt to avoid having to pay royalties, but let's say that they recognized the ballistic advantages of the caliber thanks to their experience being on the receiving end, plus seeing the Boer use of the weapon around the same time to the same effect and developed their .30-40 into a rimless 7mm version around the same length as the Mauser cartridge to approximate it's performance or adopt a .30-03 type case just in .276? Like IOTL in 1906 they'd upgrade their bullets to a spitzer type and have ITTL a .276-06 instead of a .30-06. That way they'd avoid the issues they had with the OTL .30-03. What impact does this have on small arms development then? France and Britain were going to adopt magnum 7mm cartridges before WW1, but that war got in the way and prevented the change over. Might this not create pressure on the Entente to switch over to 7mm earlier? If not would the British adopt the US 7mm cartridge in the 1920s as they were considering doing with the .276 Pedersen because the US was considering adopting it? Might the French not adopt the 7.5mm after WW1 to synch up with the US as well? If so how much WW2 small arms be influenced if the US cartridge sets the Allied standard on 7mm and all their ammo is compatible? Might the US adopt a 7mm 'intermediate' during the interwar period that was analogous to the OTL T2 Pedersen 7mm? How about post-WW2 when the NATO standard trials start? In terms of small arms would the BAR be significantly different ITTL with a lighter recoiling cartridge? Or US machine guns? In terms of weight from what I've been able to find the 7mm Mauser was only about 7-8% lighter than the M2 Ball .30-06, so there isn't a substantial weight savings like there was with the Pedersen, but the recoil would be significantly less, as would the thermal load of the cartridge, while the ballistics would be quite a bit better due to muzzle velocity and sectional density of the bullet resulting in a very flat trajectory. The differences are enough that there would be room to create lighter weapons than the OTL ones. Thoughts?