- SS tight bore barrel (typically PDI or maple leaf).
- hop rubber (typically flamingo 50 or nineball airseal).
- maple leaf I-bar.
those 3 upgrades will typically cost me £45-60 (barrel being the most expensive bit) per RIF and makes a world of difference to the performance of the RIF.
I dont own any AEGs, so these upgrades are specific to GBBP and GBBR… but a decent inner barrel and hop bucking would be helpful for an AEG as well ?
Most of my guns don't have any upgrades but on the rare occasion I do change something it's usually the hop rubber.
It's worth posting that IMO you should always play a game or two with the gun totally stock rather than upgrading parts beforehand. This gives you a better idea of what, if anything needs changing