N/A Easy way to get regulator in the ballpark for a desired tune?

When trying to figure out what pressure to set the regulator to for a desired tune, does anyone else shoot the gun below the reg pressures to at least get an idea?

When I first started tuning my gun (Taipan Veteran Long) almost 5 years ago, it was such a guessing game. I knew what FPE I wanted to tune the gun to, I just didn't know where to set the regulator to get that desired tune. I've read suggestions regarding rule-of-thumbs for how much FPE a gun will get for a given barrel length and reg pressures.

I needed to be much more precise in the tune. Also, if anyone is familiar with the Taipan Veterans, it is a pain to adjust the regulators because you have to disassemble the air cylinder to get to the regulator. Setting the regulator some arbitrary amount, re-assembling the gun, airing it up, only to find that I've gone too far or not enough, only to go through the cycle again.

What I thought was, I could shoot the gun below reg pressure and carefully document both the FPS and the fill pressures after each shot. That way, since the gun is shooting below reg pressure, the fill pressure on the gun is what's in the plenum. This also means that the hammer spring tension is maxing out the velocity by the mere fact that there shouldn't be valve lock since the gun is shooting way below reg pressure (this assumes that the gun is properly tuned to begin with). Might also work great on guns with a manometer for the plenum. Avoids all the trials and errors of setting the regulator. Just have to make sure that the gun's current tune (reg pressure and hammer spring tension) is above the desired outcome tune before starting the test shots over the chronograph.

I know guns are all different with different valving, hammer weight, hammer spring etc., but at least for the Taipan Veterans, this method works great. Might also be helpful in getting other guns in the ballpark. I've tuned both the Long and the Standard Veterans multiple times with this method and I've always hit my target on the first try. Of course, have to make sure that the gun's manometer is actually accurate before doing all the test shots.
 
If you can shoot the gun without the regulator, it would be a lot easier. You can run a full shot string to see where the sweet spot is, but I'm not sure if that's feasible with the Tiapan, I've never worked on one of those. Your idea should work, you will just have to crank up the regulator a lot.
Yes, with the Taipan it wouldn't work. One thing is the regulator takes a decent account of space compared to the plenum. Also, there is a hole in the Taipan's air cylinder in line where the regulator sits. It's used to leak air outside if the regulator seals ever start leaking. I'm other words, the gun will not hold air at all without a regulator installed.
 
I attack tuning slightly differently. I want to know where the gun maxes out as it comes. I'll adjust the hammer spring to find the max and then note the reg pressure for that max. From there I'll figure out if I need a 10 bar or maybe a 20 bar step either up or down to get where I want to be. From there is may take a few adjustments to find a good place for the reg.

Also - how much of a reg adjustment comes from experience as well. What caliber? How long is the barrel? How adjustable is the gun? Are my tune expectations realistic? If I tune X gun for Y power how will the shot cycle be? There's so much into knowing what can be expected and still have an airgun that is enjoyable to shoot.
 
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