Umbrella Prometheus 6.03 EG inner barrel w/ R-Hop and Prowin M4 Hopup

Lapping Service? (+$100)

A truly timeless, tried and true setup.

Prometheus 6.03 EG inner barrel with installed R-Hop modification. Available with a pre-assembled drop in kit for compatible TM spec M4 type AEG/HPA Airsoft guns.

The perfect upgrade for any gun, to increase accuracy, range and consistency of each shot fired. Out range anyone else on the field with incredible range and accuracy despite FPS.

Our handmade R-Hop has been an integral modification we perform for all our builds as users can experience 30% increased effective range over non R-Hopped barrels.

Purchase in a complete drop in assembly configuration for a true plug and play upgrade process if your build uses a Tokyo Marui spec M4 style hop up unit.

If you just want the Prometheus Barrel R-Hopped click here


  • Inner diameter: 6.03 millimeter 
  • Polished finish
  • Precision, hand fitted R-Hop patch
  • R-Hopped glued into hop window 
  • Umbrella Armory specific R-Hop 2.0 patch design and material
  • Requires flat bucking and M-Nubbed / R-Hopped style hop up arm for use (included/assembled with full set)
  • Use .28 gram BBs or heavier to see optimal long range advantage over non R-Hopped comparisons


  • SUS 304 stainless steel inner barrel
  • Rubber R-Hop patch
  • Rubber soft type Madbull blue bucking
  • Aluminum ProWin Hop-up unit with plastic rotary style adjustment wheel
  • Resin 3D printed UA Hop-up flat arm and reinforced C-clip
  • Rubber barrel stabilization, air seal, spacing O-rings*


  • * = Barrel + Flat-Hopped Bucking + M-Nubbed Hop-up Unit variant only
  • Lifetime warranty
  • Made to order for some variant options, up to 4 week lead time
  • Manual/FAQ
  • Return policy

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