So I came across a very interesting historical report a little while back: https://www.everydaymarksman.co/resources/kent-report-1930/ Basically a guy at the Aberdeen Proving Grounds was advocating for a small caliber, high velocity cartridge in 1930s and wrote a technical report about why the concept was superior to the existing .30 caliber and was later republished when the push for the 5.56mm cartridge came in the late 1950s: https://apps.dtic.mil/dtic/tr/fulltext/u2/705381.pdf Part of the reason it wasn't due to the 1000m standard of the day. Thing is the 6mm caliber is capable of being a 1000m round, as has been shown by the marksmen community today (6mm caliber is one of the most popular for long range shooting) and by work done in the 1970s on the 6mm SAW cartridge and as argued in the 1990s by Stanley Crist: https://www.g2mil.com/6mm_optimum_cartridge.htm So what if some enterprising officer like Julian Hatcher took note of the report and resurrected the 6mm Lee Navy with a modern spitzer boat tail design and got it accepted as the basis for the US Army semi-automatic rifle project? The .30-06 would remain the belt fed machine gun caliber, but all the other rifles and autorifles would use the modernized '6mm Hatcher Army' cartridge. This would retire the BAR, as it was way too much gun for the cartridge, and open things up to a lighter Johnson LMG and larger capacity Garand. That not only makes the Garand considerably lighter and arguably easier to design given the light recoil of the round, but also does the same for an automatic rifle while enabling at least a 30 round magazine. Meanwhile the ballistics and penetration ability of the bullet would be substantially better than the .30-06 M2 Ball due to the ballistic form and sectional density of a long 6mm bullet, which also grants it a better ability to tumble if the ogive of the nose is long enough (helps shift the center of gravity to the rear) and that was the effect of the 6mm Lee Navy back in the 1890s. Seems like it would grant a pretty decisive small arms advantage, especially as it would allow an autorifle/LMG to be less than 5kg and arguably cheap enough to make 2-3 per squad viable compared to the BAR, which only had production large enough in 1944 to really allow for that, but still weighed nearly 9kg, double the weight of something like a 6mm Johnson LMG (the .30-06 version was less than 6kg). Not only that, but the ammo would be about half as heavy if the 6mm Lee Navy cartridge is anything to go by (this round would be lighter), which enhances the firepower of a unit equipped with it, as they could fire a lot more lead at the enemy than with the .30-06. It would also heat up less quickly due to the lower powder charge too. So thoughts? Seems like the US Army could have it's cake (1000m range) and eat it too (all the benefits of small caliber while still having a role for the .30-06 stockpiles without having to design a new bullet for the Garand).