If when you order, you specify that you want to try shooting without the gas checks on, I'll cut the check shank just long enough to hold the checks properly. Sometimes heavy bullets set up like this will outshoot plainbased if the check shank is left full of lubricant.
With a 340 gr I'd guess you'd have a 90% chance of liking it, but only testing will proove it. Of coarse, it WILL shoot accruately with gc's so you can't actually lose. Heavier will not hit harder, nor kill as well as this weight. In fact a 320 gr probably would be the superior killer, due to higher velocity potential, which makes the wound diameter larger, producing faster leakage of red liquid.