Extended mags are hugely important here. The 18 round Hemlock can go to around 30 I believe which makes a massive difference.Personally I think the TTK is fine but perhaps the TTK and default ammo count aren't fine. Assault rifles with 18 bullets feel quite weak overall.
Often, if a guy has full shields, I won't even down one guy with a single clip. That can make gunfights feel a little silly, as you dance around and reload.
I feel that over time we'll get better with ammo management. Ammo takes up space in Apex whereas in most other major BR's we're used to farming ammo due to it not taking an inventory slot. Coming into Apex there's an adaption curve in that regard so I think that's often to blame currently for many folks struggling with ammo.