Changing to a 6.02mm will increase your FPS. Air volume, air pressure, air seal, and spring strength are the factors that affect FPS.
How much energy your spring is adding to how much at air what pressure with what degree of transfer to your BB.
A tighter barrel gives you a higher transfer. These barrels won’t necessarily increase accuracy (and the range gain from that amount of FPS is minimal at best), you sticking with your stock barrel is a very viable option, but there’s nothing wrong with aftermarket barrels like the ZCI, or “premium” options like the Lambda SMART or “Five and One”.
To get more RPS/trigger response, you have to work with a balance. Basically, if your gears are cycling too fast, they will catch the piston before it fully returns, causing bad wear at best, and at worst, catastrophic gearbox failure.
The answer to this is to make your spring stronger, so the piston returns faster and the gears catch at the right time. The trouble is you’re now increasing your FPS, which may put you above field limits. It’s a give and take.
If you’re taking it to a tech anyways, they’ll have their own way of doing things that’s likely to be completely different from my own. However, here is what I would do, assuming you’re trying to stay under UK rifleman joule limits:
According to my calcs, you’re at .80J with .28g. This isn’t too much room to work with.
First off, I would change to a neodymium 30K motor. The cheap option is a motor from ChiHai Shenzhen, who OEMs for a massive amount of companies. I was able to get any RPM shipped to me in the USA for $40 USD.
The more expensive option is a Tienly, which you really don’t need.
You could also use an Arcturus 28K 19T if y’all have them available in the UK.
The only reason I don’t recommend the SHS high torque or the ASG 30K boost, is that neither are actually 30K, instead clocking in at about 35K, which may be a little fast.
After you have a 30K motor, the RPS should be in between 20-23, and you now have the power to pull whatever gears and spring you want.
Assuming you’re not getting PME or double firing on this setup, you can now play the balance of using faster gears (16:1, 13:1, SHS/Rocket being the recommended brand, which should land you 25-27 and 29-31 RPS respectively), and trigger response to match.
If you find you’re getting PME, or double shooting, the answer to both problems is to short stroke, and then increase your spring power. All techs will do this differently…
I would short stroke two teeth off the release side and use a true M110, and change spring power as needed. I trust springs from Guarder and PDI, as they are both hard springs that don’t lose power over time. Soft springs (SHS,etc) will lose power, bend out of shape, and can cause serious wear and damage to your other internals.
As a side note, the easiest way by far to increase your RPS and response is to use an 11.1v LiPo. If you get double shots, see above.
And, as another side note, you can shorten your inner barrel to decrease FPS, which will give you more room to increase spring power. With a shorter barrel, more air is wasted, and the BB doesn’t have time to take advantage of it.
I have a build right now that shoots under 1J at 35 RPS, thanks to having a super short inner.