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vent hole diameter

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I need to drill the vent hole on a .62 caliber Royal Navy service pistol. What is the recommended diameter?
I'm going to try to search your answer here as I dint know it off the top of my head.
Question for you though. Do you have a set of what are called "number drill bits," or # drills?
These will let you creep up on the ideal size.
 
I need to drill the vent hole on a .62 caliber Royal Navy service pistol. What is the recommended diameter?
Just pulled from the 1st topic that looked good in my search, there are more responses here,
https://www.muzzleloadingforum.com/threads/vent-hole-size.121754/
Screenshot_20220115-082713_Chrome.jpgScreenshot_20220115-082659_Chrome.jpg
So, apparently more info is needed.
But, somewhere between these two numbers lies the ideal.
 
I went with a 1/16 drill bit and found it to be inconsistent at best. Later drilled and tapped 1/4 x 28 and installed a ventliner from TOTW, been happy ever since. Before the ventliner 3 to 5 shots and I would have an ignition issue, after the ventliner 15 to 18 shots without wiping the barrel or picking the vent.
 
All of mine have liners and all are 1/16" some originals MUST have been a good bit larger however since they didn't have liners back in those days and I have read often of soldiers and frontier folks turning the gun on its side and tapping a couple times in order to prime the pan from the charge. I would think you would need a bigger vent hole than 1/16" to reliably manage that!
 
I drill out to 1/16" but often enlarge to #51 bit which is ..067. I've never asked why but Jim Chambers Whitening liners come smaller than 1/16 and he says to not drill them out. I've drilled them out since he first starting selling them with good results.
 
Many years ago the Bevel Brothers did some serious testing and came to the conclusion 1/16th coned did the best at reliability and accuracy. So that is what I use and am happy with it.
 
Many years ago the Bevel Brothers did some serious testing and came to the conclusion 1/16th coned did the best at reliability and accuracy. So that is what I use and am happy with it.
I've lost touch with what the bevel brothers are up to. Their information was very well considered and spot on. One thing I know is that small vent hole is best for optimal accuracy (probably why Jim Chambers does want his whitelightning drilled out larger. I believe the 1/16" is a very good comprise for accuracy and reliability of ignition. I have experience with my rifles that were used in many matches that were strong winners with 1/16 vents that after thousands of shots wore out vent to .080 and accuracy hit the basement.
 
White lightning liners, I use them as they come, with one exception. I used a 1/4" liner on a .58 and after the first shot it had a delay so I opened it up a touch, 50 or 51 drill I think, works fine now. On barrels without a liner I start at .070 and go from there.
Robby
 
A question for all those advocating for a 1/16" diameter hole. And I'm not questioning or criticizing your choice, I just want to be clear.
The 1/16" hole seems also to be the smallest anyone advocates. But, a few mention using this with a coned liner and using larger when direct drilled through the barrel wall.
If you are successfully using 1/16" are you using a liner or not?
 
I usually drill out to 1/16". My numbered drills are rounded to .063 for the 1/16". That bit seems a tiny bit larger than 1/16". I use it most of the time. Another factor is length of the liner channel. That depends on the liner manufacturer and the installation. Track's copy of Chamber's liners seem to have a longer channel than Chamber's original version. Probably because the internal cone is smaller. If I get one with a long channel, using a handcranked drill for more control, I countersink the outside with a larger bit. To me a channel should be about 1/64 to 1/32". A knife edged hole "might" be a shade quicker but will burn out faster.
 
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I almost always remove the liner on every gun and deepen the inside cone to where the powder comes right up as close to the outside of the liner as possible. In fact using good light you can see the main charge granules inside the liner.
 
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