I've got a 0.177 Theoben MFR, currently doing around 24ft/lbs for the purposes of legally practicing 'Practical Long Range Shooting' in my own back yard (18 acres). We don't need a license over here for air rifles below 0.25 no matter their energy rating.

I've recently been thinking of upgrading it to a .20 (flatter trajectory, less affected by wind, etc) and hoping to keep muzzle velocity to over 1000fps, but below the speed of sound so as not to affect pellet flight stability.

However the more I read, the more I'm not sure about really needing that high a velocity.

Objective: Hit 1" targets at 10m through to 3" targets at 100m+ . 1 round per target, and a hit is a point scored. (60 targets, highest score wins)

So the variables that I could play with are:
1. Pellet (weight and BC)
2. Barrel length & twist
3. Pressure (amount and consistency)

1. Pellets: (not a lot to choose from in .20)
Crosman Premier .20, 14.310 grain, 0.0260 BC
H&N Barracuda .20, 13,27 grain, 0,027 BC
...and they're fairly similar

2. The 19" barrel seems to be a good option, but I'm just not sure on twist for long range.

3. I would prefer to keep a regulated system in place for consistency between shots. However; In order for me to achieve a velocity of around 1050 fps, I would need around 37ft/lbs of pressure, which to me seems excessive, and secondly I'm not sure I'll get a regulator to handle that pressure (if so where?). I can also only think that the pellet skirt would get significantly deformed in the barrel at this pressure, and that would probably increase the chance of tumbling rounds which would in turn reduce the accuracy of the rifle, let alone adding reams of lead down the barrel after each shot, resulting in cleaning, priming, etc (round in circles)... and ultimately reducing barrel lifespan.

This got me to thinking... there must be a sweet spot balance between pressure, accuracy, barrel length and twist...

So based on the above objectives, any comments, solutions, etc ?