Vent hole size lesson learned!

[mark davidson]

Here is an experience I just had FWIW. I got my new Hawken and accuracy was great! I got two holes over and over  that were side by side at 100 yards and ranged an inch or at most 1 1/2". I initially had some misfires and not knowing exactly what the culprit was, I decided to open the vent hole to 5/64ths as I had read that this was a common step to increase reliability and maybe even speed of ignition. Well, in short, here is what happened. Ignition reliability improved but accuracy went out the window. My gun with no other changes whatsoever went from basically an "inch" two shot rifle off the bench to shooting two shot groups that were 8 to 12 inches apart! With the same clean bore and the exact same powder and patch and ball combo and the exact same bench and loading procedure, my gun all of a sudden began vertically stringing bullets close to a foot apart. I then took the drilled out vent liner out and replaced it with an identical one that had not been drilled out and my gun immediately returned to its former inch to 1 1/2" performance! I am so new still that I do not know what the exact problem was but I suspect that the larger hole was letting gas escape out  the vent hole in more volume than before and in a less consistent way causing velocity to deviate mightily resulting in an extremely inaccurate vertical stringing grouping. A little tuning on the lock springs and frizzen corrected all misfires and made the rifle completely reliable but I will not for now consider drilling out another vent liner. I just thought I would share this experience and see if any of you have had a similar thing happen or see if any of you could confirm what I suspect to have happened. As always, thanks in advance for taking time to read and ponder. :-)

[Ohio Joe]

Mark, I have had that happen as well.  Best thing to do (IMHO) is to leave the liner hole alone for now and get in the habit of, "pick and prime."

With this said, and with the accuracy you are now getting,,, you should be able to read your groups and know when it is time for a new liner in the future when the hole begins to enlarge.  However, I have stainless steel liners in my flinters and I have not shot one out as yet - at least that I can tell.  I also quit enlarging the hole.

Another option would be to shoot a heavier charge with the enlarged hole.  But if you're getting 1 to 1 1/2 inch groupings at 100 yards from the bench, then it's awful tempting to "not" mess with your load.

[Mitch]

yep, I changed a vent liner the night before going hunting....long story short, I shot right over the deer at 60yds...a long time friend and gunbuilder told me to use the smallest hole that will get ignition.....Another friend of mine has a "self-priming" Bess!! the vent hole looks big enough to stick a finger in it!! he just loads it, raps the butt on the ground and shoots....