GBL Airsoft "The Captain" Metal Hop-up Unit for GHK M4 Series Airsoft Gas Blowback Rifle

"Captain America hop up is the best hop up I ever seen in my life im a fan boy of GHK and GBL I recommend this upgrade to everyone!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

"I actually bought this to install onto a G&P WOC Challenge kit. Since it was made for the GHK system, there are two timing tabs and one must sanded off before it�ll fit the G&P barrel extension (or, conversely, an extra notch must be machined). Build quality is good, but the hopup arm has slightly loose tolerances and could use a bit of shimming. A large o-ring snugs the unit into the barrel extension as well as steadies the hopup arm.

The biggest benefit of getting the GBL is that it allows the use of VSR type buckings and barrels. The unit includes what appears to be a Maple Leaf (ML) Delta bucking. I installed it with an ML Diamond instead (with the split nub), along with an ML Crazy Jet barrel.

The GBL solves the accuracy problems I was having with the G&P kit. Previously I had swapped the stock hopup/barrel with a stock GHK unit/AEG barrel with only marginal improvements. So, in short, I�d highly recommend the GBL unit. If it could improve a G&P it�ll surely improve any GHK M4.

Disclosure: All testing was done with a GHK G5 magazine, modified to fit the G&P mag well.

"I bought this because I needed a new hop up... GHK STANAG mag feed lip broke, I double fed, and burst my plastic hop up... but MAN IS THIS AMAZING. I'm actually glad I had a reason to upgrade! The metal is extremely well built. When I'm double feeding, it just breaks the BB and I walk off to clean it off real quick. The bucking didn't want to co-operate to well upon insertion to the unit itself. Use a lot of lube and just don't give up. VERY SOLID PRODUCT, all the GHK players on my field use this product, or the TNT hop up system, the two option are simply the best for your GHK M4. Don't forget to pick up an AR wrench or you will never be able to change this yourself, otherwise get a tech to change it.