Mark, it seems that even among those with long experience in flintlocks will disagree on this one. I agree with Mike Brooks. Any vent larger than 1/16th will cause some loss of accuracy. It seems that the smaller the vent, the more even the pressures with a given load. I have never had ignition problems that were due to the smaller vent, but years ago when shooting cap guns, I knew when I needed a new nipple as my groups would open up. I would replace the nipple and groups would immediately shrink back to their original size. Some fl's seem to benefit in reliability when the vent is increased, but I have always felt that the problem really lies elsewhere, if there was an ignition problem to start with. Back to the cap guns, had I increased the charge a few grains instead of changing the nipple, it is possible that would have over come the burned out nipple and also brought the accuracy back. I don't know. The gun I was shooting was very picky about the nipple hole size. I get ignition comparable to cap lock speed with my 1/16th vent, but I use a liner that I opened the cone out wider than it originally came, and gave it a small outer cone, ending with a fire channel of maybe .030. I rarely get ignition problems even after it is heavily fouled. I built a Virginia type for a friend, with an L&R Queen Ann, and it has a constant slow, and unreliable ignition that even a larger vent has not helped. We are still working with it though. It has the same vent that I do, but we have the larger hole with no gain in performance.
