Flash Hole size?

My Lyman GPR 54 caliber plains rifle is the last month they were having them made by Investarms and it has little be desired and so my approach on it is going to be like a kit rifle so I get it to where it's acceptable to me. Long story short I'm told since I've been having trouble with the powder charge going off consistantly to enlarge the flash hole between 1/16" - 5/64". With that said I should also be able to use FF in both the barrel and the pan if it all is working well. Your thoughts? Headed to the range now for some more play time before I drill it out.

I don't think I'd go any bigger than 1/16" (.0625"). Also the backside, the breech side, if it's flat drill a concave face on it maybe 1/4".
Another tip is when you load and before you seat your projectile of choice tap the butt on the ground or tap both sides of the stock with the palm of your hand to settle the powder and get it against the vent hole.

Bronko, Yeah I've tried all of that and every variation of that. If the powder isn't leading or going in the flash hole it won't light however when it does go off it's like lighting a wick with the hangfire it has. Thanks though!

Never go over .035, There is a good reason why that Flash Hole is tiny from the Factory, there is a TON of pressure coming back through the Flash hole, and your eye is right there. For Substitute powders such as Triple Seven, and Pyrodex I advise opening the flash Hole to NO MORE than .033, you need to be precise here, I use Pin Gauges, and precise Wire Bits.

The TC Hotshot Nipple has the Largest factory Flash Hole i have ever seen at .035, My favorite nipples are Treso/Ampco’s they have a tiny .028 Flash Hole, they are geared toward Real Blackpowder.

Back in December I noticed my Pedersoli 12gauge would have the hammer recock after shot. They always went off, but when I took out the nipples and looked it appeared the original owner bored the out big time like maybe bigger than an 1/8" it was huge! Old guy hadn't shot since the late 70's so I'm sure he did what it took to make it fire.

Big Sky Bryan wrote:Back in December I noticed my Pedersoli 12gauge would have the hammer recock after shot.  They always went off, but when I took out the nipples and looked it appeared the original owner bored the out big time like maybe bigger than an 1/8" it was huge!  Old guy hadn't shot since the late 70's so I'm sure he did what it took to make it fire.

I was on a Facebook Group a few years ago, there was a Guy talking about his Lock “Self destructing” I asked him what he meant? He said after he Shot the Hammer came Back so hard that it Broke the internals of the Lock    I immediately asked him about his Nipple Flash Hole Size? Yep, he had Bored the Nipple out as large as he could to get reliable ignition  He was advising folks to do this  He & i went around & around over it, That is just Plain DANGEROUS.

Apples and oranges here.  A nipple or BP flash hole I agree shouldn't be larger than .035 but a touch hole is a different animal. Black powder mag did a test using the same barrel and starting at .040 kept increasing the vent/touch hole size up to .094".  It was found that anything over .062 you started reaching a point of diminishing returns. Smaller diamonds. lead to unreliable ignition of the main charge. .062 seemed optimum.
If it makes you feel any better I also had a Lyman GPR flintlock that was really finicky.  I got rid of that after sneaking up on a nice bedded buck in the snow.  Cocked the hammer, lined him up in the sights, pulled the set trigger, and touched off the shot.  All I  got for my effort was a Pffft and a white tail waving good bye!  Traded it in the next day.

Bronko22000 wrote:Apples and oranges here.  A nipple or BP flash hole I agree shouldn't be larger than .035 but a touch hole is a different animal. Black powder mag did a test using the same barrel and starting at .040 kept increasing the vent/touch hole size up to .094".  It was found that anything over .062 you started reaching a point of diminishing returns. Smaller diamonds. lead to unreliable ignition of the main charge.  .062 seemed optimum.
If it makes you feel any better I also had a Lyman GPR flintlock that was really finicky.  I got rid of that after sneaking up on a nice bedded buck in the snow.  Cocked the hammer, lined him up in the sights, pulled the set trigger, and touched off the shot.  All I  got for my effort was a Pffft and a white tail waving good bye!  Traded it in the next day.

I was strictly talking Nipple flash Hole Size, I know absolutely nothing about Flint Locks they call them “Touch Holes” right?

I was talking flint lock.

I've read pretty consistently that 1/16" is about the money spot for touch holes. My pedersoli has good ignition sometimes, a little delayed others so I'm thinking about opening it up a bit more.

Yes Lewis the OP was talking about flintlocks. They are called touch holes or vent holes. Take my advice and don't start shooting them! You think shooting your caplocks are a challenge? The flinters are even worse. Not only do you have to find the best bullet and powder and charge for it for best accuracy but you also have to play with the flint for the best location for the utmost spark from the frizzen AND how much powder is needed in the pan without covering the touch hole. Oh yeah, its also a good idea to know how to knap your flint to keep it nice and sharp because a worn flint won't spark enough. I've been shooting them since about 1972 or there abouts. (wow - that's almost 50 years!!!)

Bronko22000 wrote:Yes Lewis the OP was talking about flintlocks. They are called touch holes or vent holes.  Take my advice and don't start shooting them!  You think shooting your caplocks are a challenge?  The flinters are even worse.  Not only do you have to find the best bullet and powder and charge for it for best accuracy but you also have to play with the flint for the best location for the utmost spark from the frizzen AND how much powder is needed in the pan without covering the touch hole.  Oh yeah, its also a good idea to know how to knap your flint to keep it nice and sharp because a worn flint won't spark enough. I've been shooting them since about 1972 or there abouts. (wow - that's almost 50 years!!!)

Damn Bronko that’s a long time, I was born in 1972

And it just goes to show that you can teach an old dog new tricks. I'll be the first to admit I don't know everything and even a young whipper snapper like you taught me a few things!
BTW that saying: you can't teach an old dog new tricks - that was started by an old lazy dog...

Bryan I'm not sure about using FFg in the pan.  I've heard of using FFFg in the pan but not FFg.  I always used FFFFg.  The finer the powder the easier it is to ignite.  I think with FFg you'd be pressing your luck.
You could probably use FFFg both as a charge and a priming powder. If you don't want to buy FFFFfg you can, in a pinch, crush up a small amount FFg in a bowl with a wooden dowel to get the granules about half their size and put them in a container for pan priming. Just don't use anything that could cause a spark or collect static electricity or POOF - no eyebrows or worse!

I have used FFG in the pan with great success.

https://youtu.be/whrbhEBoQP8

Hi Hillbilly 57 here
I discovered a trick on a flintlock for better ignition
After I’ve loaded the gun I take my vent pick and insert it into the powder , it seems to make a channel for flash to travel .It is a Kibler kit gun , my next thought might be to drill out flash hole to 1/16
As it is it’s as quick as most I’ve seen shot .
It dosnt cost anything to try this trick .

I just ordered a .033 & .034 pin gauge as I know my Original White Breech Plugs might be getting too large. I have that solution fixed. I've ordered revised breech plugs from Bestil on another forum that enables me to replace the nipples.

Bryan, I’m just catching on to this conversation now. I shoot primarily flintlocks. 1/16” is a standard size for touch hole diameter. If my guns are shooting well with this I leave it alone. I have several flintlocks where I drilled out the touch hole to 5/64” to fix an ignition problem. The flintlock Hawken I’m shooting now had a delayed ignition, frequent flash in the pan problem and required picking out the touch hole continuously and that didn’t always help. I drilled it out to 5/64” and problem solved. I must have shot at least 30 times today with good ignition each time. As for priming, I always prime with the same powder I use to load the gun and never carry 2 different powders. I primed with 2f powder today with good ignition.

When I'm hunting I always use speed loaders and a little pan primer filled with 4f in my jacket pocket

MNPaul,

Every time I take my GPR out I hope that it's got rid of it's attitude problem and hoping isn't working. Think I will drill it out this week.

Bryan, forgive me if you said earlier, but are you using Black Powder or a substitute?
if BP fine and good. if not and can get some do use it. subs just are asking for frustration.
1/16 is the optimal size for the vent.
do you have a vent liner? if so and the vent is smaller than 1/16 drill that puppy.
if you don't have a vent liner you might think about drilling and tapping and putting one in.
most have a cone shaped inner bevel to enhance ignition.
can't think if i have ever used ffg in the pan but fffg works great as both a main charge and priming. about all i have used for 60 years, though mine is homebrewed so it may act a litlle different.

Bryan,
If you have a removable liner and you’re still not getting the results you want you can try making a liner out of a hex head set screw. I learned this from another shooter and it worked great on 2 of my flintlocks. The hex head acts like a cone to catch the spark from the pan. The set screws I used were coned on the inside as well. May have to cut it down length wise to fit your barrel. Drill through it at 1/16” for the hole and enlarge to 5/64” if necessary. Just something inexpensive and easy to try if need be.

In this gun I'm talking about since it's a flinter I have only tried BP no substitutes. It's going to get drilled this week and I will let you know how it works.

Big Sky Bryan wrote:In this gun I'm talking about since it's a flinter I have only tried BP no substitutes.  It's going to get drilled this week and I will let you know how it works.

Definitely keep us posted

Big sky Bryan, if you do have to go 5/64's to get good ignition, be sure no one is to your right when you touch it off!