advise on getting more distance

[craigh]

Chuckin a 6 lb pumpkin 400lbs 17ft boom 8ft leads
Will longer leasd get more distance?
i am hesitant to add weight.
Getting a little sketchy

[madmattd]

Going to need more information to answer for sure. The answer is maybe, but maybe not.

67:1 Mass ratio (counterweight to projectile) is on the low side, so your sling line length might be close. Is 17' the long side or the total length? Some information on both beam lengths (long side and short side - known as the Long Arm and Short Arm respectively) would help. For a normal hinged counterweight trebuchet (is that what you have or something else?), sling lines of ~80% the length of the long arm are a usual good starting point, but that's for a 100:1 mass ratio. For a lower mass ratio like yours shorter is usually needed.

Have any video of shots, taken directly (or close at least) from the side? It's easy to help you tune it in with one of those.