All the surgeon rubbers are trash. Don't even bother with them, you are better off using the stock Marui rubber.
Stick to NineBall hop-up for your hi-capas only. And PDI barrels are worse than NineBall 6.03. I have experimented with all the barrels on the market, no joke. I ended up sticking to the NineBall 6.03 standard length for all my Hi-Capas.
The stock marui hop-up unit is prone to breaking if you are using a steel outer barrel, as it bangs up on the hop-up unit really bad causing the dial to come loose.
The Surgeon stuff is all from the same factory as Nova and Prog4. So the hop-up units are all essentially the same. Stick to Nova, its currently the most reliable on the market. My Nova hop-up came loose with however, replacing the o-ring with my own custom o-ring the dial is stiff as ever and I never loose my hop-up setting under extreme blow-back.
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