1.USF faction base infantry/support weapons has fairly high popcap requirements, even teching for LT, CAPT, MJR requires popcap. This lead to smaller army size.
The issue isn't the pop cap, it's the stock army's generally large target size combined with no mainline sandbags and lack of ranged DPS. You basically have to always move into your opponent's units as if you're using assault squads and you suffer a lot from it.
2. USF support weapons squad reinforcement cost is way too high.
Not quite, non-issue imo. Now if you wanna talk about the teching costs to get them, that's another discussion.
3. rear echelon - worst base infantry in the game for 200mp 5pop. I dont see the purpose of having them other than bunker and tanktraps (green cover)
Disagree, REs aren't that bad. They put down the green cover your desperately need and can come in clutch early with volley fire. They can be a decent weapon platform later (zook/M1919/BAR/pickup). They're honestly fine.
I think USF's core issues are
1. No sniper counter and you get just 1 vehicle soft counter that gets absolutely mauled in a real game by 222, camo&sprint and snare, tellers and 19range fausts if it dives too deep to chase the sniper.
2. Lack of ranged play in your engagements. Your only stock option is to rely on .50cals to keep the enemy at range and stop enemy LMG blobs from shredding your inf that's out in the open. Pack howies used to help but they got overnerfed.
3. Captain sidetech for an AT gun is very expensive and not worth the vet 0 M1. The M1 in general is in a very weird spot. USF would probably be better off if it got converted to a 6pdr clone but that's a long discussion and it's probably too late in the game's lifespan for this.
4. LT being the only viable tech decision alongside a LV means you are going to struggle with the stock M4 against a stock P4, especially vs a P4J. Zooks will usually bleed before they can even fire and sideteching for an AT gun isn't very rewarding as mentioned in #3. Unless you are in a comfortable situation, the 1st medium vs medium fight is usually with USF on the back foot.
5. Captain tier has become too weak with the pack howitzer nerf. AAHT is good but it's also your only suppression platform and it dies in 2 hits until vet HP bonus, meaning you don't have .50cals to deal with LMG blobs and elite squads. Pack howies are very expensive and harder to justify with the nerf. M1 is ok but generally not as good as zis/pak/6pdr. Probably better than the raketen at least.
What I'd do to USF is
1) Nerf snipers.
2) Revert some of the nerfed pack howitzer performance.
3) Slightly lower close DPS of rifles and officers and slightly increase their mid range DPS.
4) Make major an optional unit instead of what he is now (not sure with voice lines and coding).
5) Probably make the M1 a 6pdr clone.