Drilling out flash hole, Results!

[olskool]

The reason is because of the uniformity of ignition shot to shot. The same is true of brisinance in modern cartridges. Different primers and flash hole uniformity in brass cases effect accuracy and is the reason they are tried out for group size. The same thing is happening with flint lock ignition . The diameter that makes the most reliable and consistent flash migration to the main charge will be the most accurate all other considerations for accuracy being met as well.

well i would have to see it to believe it. i am not saying it couldn't effect accuracy at all but i don't think on a flintlock there would be enough difference to matter. i have been a handloader for over 50 years. unless you have a full blown bench rifle changing brands or types of primers or the uniformity in primer holes, you will not ever see a difference. but hey i am no expert with flintlocks like a lot of you fellers, i am always willing to learn,,,,,,,,,,,,,,

 

[Larry (Omaha)]

The larger the vent, the larger your groups.

I never heard that before. Not saying I disagree or agree, but can you expound on that? Is there any documented proof?
Thanks
Larry

 

[M. De Land]

well i would have to see it to believe it. i am not saying it couldn't effect accuracy at all but i don't think on a flintlock there would be enough difference to matter. i have been a handloader for over 50 years. unless you have a full blown bench rifle changing brands or types of primers or the uniformity in primer holes, you will not ever see a difference. but hey i am no expert with flintlocks like a lot of you fellers, i am always willing to learn,,,,,,,,,,,,,,

In Ned Roberts book on the cap lock rifle he points out how the most accurate competitive loads in percussion match rifles was always with the use of the least potent caps that could be found. Brisenance has a direct effect on ignition and by extension accuracy. A partially blocked flash hole in a case , nipple or flash hole will effect consistency of ignition and thus accuracy. The difference can range from minute to very obvious depending on many factors but long range shooting really reveals these differences in a big way. Most of us are shooting no more than 100 yards in muzzle loading matches and that usually in off hand position which can make the difference undetectable but they will still be there and become obvious when the bench venue is shot. That is precisely how I found out about eroded nipple orifice effects on accuracy.
We all know from experience as well as in writing that uniformity is the main key to accuracy in any fire arm past or present. Flash hole size , shape and position is how uniformity is produced and maintained in a flint ignition rifle.

 

[olskool]

In Ned Roberts book on the cap lock rifle he points out how the most accurate competitive loads in percussion match rifles was always with the use of the least potent caps that could be found. Brisenance has a direct effect on ignition and by extension accuracy. A partially blocked flash hole in a case , nipple or flash hole will effect consistency of ignition and thus accuracy. The difference can range from minute to very obvious depending on many factors but long range shooting really reveals these differences in a big way. Most of us are shooting no more than 100 yards in muzzle loading matches and that usually in off hand position which can make the difference undetectable but they will still be there and become obvious when the bench venue is shot. That is precisely how I found out about eroded nipple orifice effects on accuracy.
We all know from experience as well as in writing that uniformity is the main key to accuracy in any fire arm past or present. Flash hole size , shape and position is how uniformity is produced and maintained in a flint ignition rifle.

thanks for the explanation, but i think in real world shooting situations you would never notice any difference. but hey i will keep it in mind!

thanks,,,,,,,,,,,,,,

 

[zneufeld]

I drilled out my Lyman GPR flintlock to 1/16, and in my range session today I had no misfires and a much faster ignition time. Video below. Before I drilled it out, I was getting occasional flashes in the pan, and I would have to pack the priming powder close to the hole for a fuse effect. Now I can leave the hole clear and have the priming powder to the right in the pan.

 

[olskool]

I drilled out my Lyman GPR flintlock to 1/16, and in my range session today I had no misfires and a much faster ignition time. Video below. Before I drilled it out, I was getting occasional flashes in the pan, and I would have to pack the priming powder close to the hole for a fuse effect. Now I can leave the hole clear and have the priming powder to the right in the pan.

did it change your accuracy for the better or worst or no difference?

 

[Mulemauler]

@Fly103, this is valuable information for all flintlock users, not just Pedersoli users. One should use the smallest touch hole that gives excellent ignition of the main charge. Most liners will start out at a small dimension such as 0.055" or a #54 number drill. Most of us will find that we need to open the flash hole to 0.062" or 1/16". And sometimes using the number drills to get to the #50 at 0.070" is the best choice. The maximum I recommend opening the touch hole is 5/64" (0.078"). Most of us only have a fractional set of drill bits so the two sizes available are the 1/16 or 5/64. There are 5 number drills between 1/16 and 5/64.

54​	0.055​
53​	0.0595​
1/16	0.0625​
52	0.0635​
51​	0.0670​
50​	0.0700​
49​	0.0730​
48​	0.0760​
5/64	0.0781​

Thank you for posting this!

 

[Pete G]

1/16" seems to be the magic number

 

[B P Maniac Shooter]

All mine get popped to 1/16” straightaway.

Yep.........mine get that same treatment too.
Never regretted it either.

 

[smoothshooter]

The larger the vent, the larger your groups.

“Mechanical accuracy,” possibly, yes.
Practical accuracy from field positions, I would strongly disagree.

 

[flntlokr]

If you buy those liners with the hex tool slot on the outside, you wont have to countersink anything. It will already be done for you.

That's what I use, but I countersink the inner end more to reduce the channel length. Probably not a necessity, but that's what I like to do.

 

[Art Caputo]

Of late, I have been liking the drill size #53(.0595”) when using the White Lightning liners. I avoid liners with exterior screw slots or a Hex head recess.
I can’t say that I’ve experienced any noticeable difference in precision due to vent size. Some loss in velocity, yes. But I don’t think the degree of loss makes much of a difference considering typical distances.

 

[M. De Land]

Another consideration is the larger the hole used to peak preformance probably the faster the erosion. More gas volume escapement I would think equals faster erosion.

 

[nkbj]

Got a .52 bore flinter Renegade set up for paper patched.
Testing different hole diameters could be some fun.

 

[duca]

Interesting

 

[Britsmoothy]

Got a .52 bore flinter Renegade set up for paper patched.
Testing different hole diameters could be some fun.

I can think of a thousand other ways to have fun brother

 

[Darkhorse]

I drill out my white lightning liners one number drill at a time until I get the ignition speed and dependability I want.
.016 is good for the .40 and most .45's, while my .54's are drilled out a good bit more for hunting.
I have never experienced accuracy loss by doing it this way. But if one just drills out an oversize hole without working up to it I can see where that could have some negative effects.

 

[olskool]

my 54 SMR 50yds 3 shots off hand, the hole was drilled when i got the gun. a 1/16 bit wallows around in the flash hole. group not an accident either, this thing is never disappointing and never needs any excuse, it shoots! hard to convince me it hurts anything to drill it out,,,,,,,,,,,,,,,

 

[Darkhorse]

It certainly hasn't hurt your accuracy olskool!

 

[stewart.leach]

I have replaced several liners, and have assisted other club members with new rifles and new liners. Most new liners, and liners on new factory rifles have flash holes that are too small. I assembled a set of number drills, and enlarge one small step at a time until ignition is reliable. Most finish out at the step immediately below 1/16".