Nipple Flash hole diameter ?

[Chill Wills]

I have a number of used and new nipples and checked them all today for for flash hole diameter.
I got a wide range of diameters and that got me to wondering. How much difference does the hole size make and assuming they only get larger with time (if they do at all), when should they be retired and replaced?

[idahoron]

Excessive hole size will negatively affect groups. There are may factory nipples that measure .028 I think Hot Shots are standard at .035 I look at replacing hot shots at .037 to .038

[KCSO]

I just drop in fresh Ampco npples every season and save the old ones for emergencies. .040 and they are trashed

[idahoron]

I just ordered some how long do they last and what kind of bullets do you use?

[Chill Wills]

Excessive hole size will negatively affect groups.

Yes, that is what I think too. I just don't know how small is within the range of Okay. I would be happy to find new ones un-drilled and start small and see if accuracy changes for the better or worse as I increased the hole size.

Many of the ones I have start in the 0.040" + range. The replacement "plains hunter" barrel I put on the Lyman GPR came with a nipple. It will pass a 0.041" drill so maybe it is a thousands or more larger. ....I have one that is 65 thou. It's a candidate for lining and testing.

[dondiego]

What are you guys using to measure these holes?

[oldracer]

I have a set of "wire gauges" and they start a few thousands and go up. They were expensive as hell and I bought them to measure the hole size in Weber carb jets as they get larger over time too.

There are some posts that show the flame coming out of different nipples with different percussion caps and hole diameters. The big issue is the velocity of the flame on percussion rifles with a powder barrel since the flame has to turn 90 degrees to get to the powder. Under hammer percussion rifles are most effected by the nipple hole I would think since the flame goes right into the powder. I would suggest trying different ones to see which shoots best in YOUR rifle since picking one that last year's champion uses may make your rifle shoot like a stinker!

As for a source of the wire gauges, try to find a local place that sells machine tools such as taps, measuring equipment but NOT Lowes or Home Depot. There is a place in Brooklyn NY near where the Navy yard was and they sell everything, ALL taps and die sizes and most any thing you could imagine.

[pietro]

.

Upon ignition, the powder creates pressure that wants to go in all/every direction, like a hand grenade or firecracker.

Since the barrel's usually strong enough to contain the pressure, the pressure can only go 2 ways - towards the open muzzle (pushing the projectile ahead of it) and rearward towards the only other escape vent - the ignition channel.

The reason that both a flintlock vent hole and a percussion nipple flash hole are sized the way they come from a factory is to retard gas/pressure blowback towards the shooter's eyes/face, and to maintain propelling pressure on the projectile.

There are usually 2 signs of an eroded nipple (yes Nimrod, powder does erode flash holes larger) - reduced accuracy and the hammer being blown back to half-cock.

I don't bother closely examining or changing nipples unless I have ignition issues and/or hammer blow-back - a battered nipple cone, of course, is always subject to replacement. (YMMV, of course)


.

[Maven]

"What are you guys using to measure these holes?" ...dondiego

I'd like to know that as well. However, hobby outlets, e.g., Walthers, MicroMark, sell numbered drill sets from #80 -> #60. One of those bits and a micrometer or dial indicating caliper will tell you what you need to know.

[John Taylor]

Well it's been over 40 years and the powder tattoo on my arm is almost gone. Got me one of those H&A under hammer target rifles in 45 and was trying to get it to shoot good groups. It was a nice warm day and I was not warring a long sleeve shirt. Got my arm under the rifle and touched it off and notice my arm seemed to be on fire. Didn't know about nipple hole size and apparently this one had been shot a lot.
If you want a self cocking gun just go with a large hole in the nipple. Several years ago I saw some ceramic lined nipple for sale that were said to not burn out under the high pressure of a slug gun but the price of $25 each seemed a bit high when a standard SS was going for about $3. Now I have tried to make nipple when I was much younger and it seemed the hardest stainless I could find was in the exhaust valve of a modern engine. Try to drill a small hole in one of those and you go back to buying a nipple. The reason for going with Stainless is the same reason that stainless can not be cut with a cutting torch.
There was also the time I was standing to the right of a flint lock shooter in competition. I was just lining up on the target when I heard this crackling sound in my ear and felt the burn. Probably why my hearing in my left ear is down to 40% . New rule on the range, flinters had to say they were shooing a flint lock before pulling the trigger. A large flash hole in a flint lock can be faster but you don't want to standing in line with that hole.

[Chill Wills]

John, SS won't last but a few shots on the high pressure rifles used in Long range ML either.
This is what I have gone to in my Gibbs ML - Platinum lined nipples. Not inexpensive but they last.
The hole diameter is smaller than I can check with the smallest numbered drill in my #60 set. As said, numbers 61 to 80 can be had but I have no use for them at this time.

[Good Cheer]

Ask flintlock shooters about how hole sizes effect their groups.

[Chill Wills]

A Heppsworth Platinum nipple

It does not list the orifice size.

[Boz330]

Mike, Dick Hoff and Kenn Heismann did a lot of experimenting with nipple size and they came up with .025 to .028 as being optimum. You can get a set of welders torch tip cleaners for checking hole sizes. Kenn had a nipple burn out during his 1000yrd stage at the 2015 world shoot and his group went to hell in a hand basket.
Dick did a lot of experimenting with different nipple metals and some of the stainless holds up really well, others not so much. He was disappointed in the platinum lined nipples after he had to pick a liner out of his forehead. He got with a rocket engineer from GE jet engine division that he shot with and they came up with a new design and resistant metals. The ones that have been tried are lasting between 1000 and 2000 shots before they go south. I have one in my Gibbs that has 600 to 700 rounds through it with no wear so far.
Here is a link to a post on the nipples; http://castboolits.gunloads.com/show...-drinking-beer

Bob

[Chill Wills]

Bob, That is good info you write. I have not opened the link yet. I will check that out later. My son and I are just getting out the door to do some fishing.

Things have changed so that I can shoot the Oak Ridge match again so I will be (hopefully) using up nipples again as a result. In a good way, this thread morphed from hunting rifle nipples to high pressure LRML nipples. I will be talking to Rick Weber soon, is he still making lined nipples? My last ones are from Joe so you know that has been a few years ago.

[Boz330]

Bob, That is good info you write. I have not opened the link yet. I will check that out later. My son and I are just getting out the door to do some fishing.

Things have changed so that I can shoot the Oak Ridge match again so I will be (hopefully) using up nipples again as a result. In a good way, this thread morphed from hunting rifle nipples to high pressure LRML nipples. I will be talking to Rick Weber soon, is he still making lined nipples? My last ones are from Joe so you know that has been a few years ago.

Great, I look forward to meeting you in person, Lord willing and the creek don't rise. Check your inbox.

Bob

[Edward]

Do not want to get off topic ,but does anyone venture a guess on erosion on a Magspark using 209 primers as it is a closed system ? My barrels have all been vented as per johnson 1942 advisement and I do not think (not sure) if erosion is evident but have not noticed any enlargement so far /still looking /Ed

[oldracer]

I have been using them since 2012 on several rifles including one built by Roger and so far I have not seen any issues.

[Chill Wills]

I received a Dixie $10 gift certificate as a door prize and redeemed it for two Ampco 6-.75 MM 0.028" nipples for my Lyman GPR. I am not sure if I will be able to see a difference on paper with this hunting rifle or not but I am sure going to give it a try at 50y and 100y.

I used to shoot the 54 Maxi-ball in the slow twist barrel (1 in 60) and it shot very well. Just this summer I fitted a Lyman "hunter" replacement barrel with the faster twist to the rifle. It might be a 32 twist but maybe a 48". I better check but it does not mater. It is what it is.

The nipple that came with the hunter barrel measured about 0.041"+ which is surprising maybe. I have been getting three inch groups at 100yds in this new barrel which is about all I need and expect of a ML hunting rifle, but it maybe interesting to see if a smaller nipple orifice changes anything.

For about $10 ebay will deliver a set of 61 to 80 numbered drills. If for nothing else, I may get them to use as hole (pin) gauges. If I never drill a hole with them that will be Okay.

[Chill Wills]

I just drop in fresh Ampco npples every season and save the old ones for emergencies. .040 and they are trashed

I ordered two of these using a door prize certificate and checked the flash hole when they arrived. The flash hole will just pass a 0.027" diameter wire. I changed out my old nipple and test fired the rifle a few times over the past few weeks. No real change in accuracy. That just may be the new barrels ability limit or I have not found what it likes. The old barrel shot about everything well.
No worries tho, it is plenty accurate for hunting next week.

Two odd things about these Ampco nipples, the #11 caps I have, all brands are a very loose, fall right off loose. Pinching good them only helps a little. I am going to need to address that better for hunting. The second thing is the flats are wider than any other nipple I have used on this rifle and the wrench won't go on them. I had to lightly grind and file them to fit so I could use the wrench. About 0.010" did it. They are harder then woodpecker lips.