>>63988517 (OP)This is almost certainly bait but I'll bite for fun. I'll start by saying volume of fire is the #1 factor in winning an infantry gunfight, period. This is not debatable, every data point from every war in recorded human history backs this up, it even applies to things that are not guns such as arrows, javelins, and slings. For any given hit rate you want to put as many rounds down range as possible. Battle rifles such as the NGSW (all of them, not just the SIG), AR-10, etc. are fundamentally opposed to this very simple fact with bulkier, harsher-recoiling ammunition that you can't carry as much of, and can't dispense as much of in a given time frame. The M7 and M250 are both total non-starters for this reason.
>But muh Bumfuckistan mountainand desert warfare>>63989487>>63989610Basically this. If you really need more than what a gucci free-floated 20" AR-15 in 5.56 can do, the way forward from there is NOT a battle rifle, provided you're okay with procuring something as new and radical as the M7 - it's a gucci free-floated 20"-24" AR-15 in something like .224 Valkyrie or 6mm AR. Yes, total intermediate action supremacy.
>But muh barrel lifeSuch a rifle is by definition serving an edge case, so it doesn't really matter. Most likely the only correct assessment in the entire NGSW program.
Not a machinist but I have a sneaking suspicion you could recycle shot-out 5.56 barrels into 6mm barrels too by boring them out. The cartridge is physically larger so the chamber would be cut into fresh steel too. Don't quote me on that though.
On the machine gun side, belt-fed AR-15 uppers like the ARES Shrike and FightLite MCR have proven that the AR-15 can be turned into a VERY light LMG at least in principle. I believe both were piston-op but the original DI system is usable at LMG-tier volume of fire if you bulk up the gas tube a bit and make it out of something like inconel. So the machine gun side of NGSW is totally barking up the wrong tree, too.