What happens when you get rocket enginners and ML shooters drinking beer.

[Boz330]

My shooting buddy, who is on the US long range muzzle loading team, had a terrible time getting good ignition on his Gibbs rifle at a match. The weather was cold and wet. He shoots a small bore league on Tuesday evenings with a bunch of engineers from GE jet engine division. After several beers they started discussing the problem and decided to apply some supersonic gas flow jet engine designs to the percussion nipple.

Of course the other problem with the nipples on LR guns is gas burnout of the nipple hole. This is typically alleviated by using a Platinum lined nipple which is very expensive. They got some sample of a couple of different stainless steels and some inkonel(SP) and had a machine shop turn out a number of standard nipples out of these metals. They had a reamer made to form the internal contour of the nipple to channel and concentrate the gases.

Next problem was how to test the design for efficiency. They came up with a barrel setup that would use the fire from the nipple to propel a pellet across a chronograph so they could compare the different designs and caps. Before they got to that test they decided to just do a comparison with photos of the fire in a dark room. These are the photos of that comparison.

First of all the fire you see is after it has traversed 3 inches of barrel. The top picture is of the redesigned nipple. The next one down is the same nipple before it is reamed with the new configuration. The 3rd down is a Platinum lined nipple. The 4th is a copper beryllium nipple. Number 5 is a stainless steel nipple developed by the South Africans that has held up pretty well to the gas cutting. The last is a custom made nipple that Lee Shaver makes for his Custom Farris LR rifle. In the pictures where you see some of the sparks deflected down it is because there is a piece of paper at that distance. The telling thing though is the length and strength of the fire exiting the barrel.

Bob

[Hanshi]

What conclusions did you and your group arrive at? # 1,2,4 and 5 look about the same though differences in the brightness among the six are noticeable.

[fouronesix]

Whomever set up the test, well done!

I'd choose #1. If repetitions show the same results, then #1 appears to be better. Just guessing though as it may depend on how the powder responds both in speed of ignition and consistency of ignition with fouling.

[GARD72977]

That is a very neat test but not sure I see the relevance in how far the sparks go.

[rodwha]

I want to drink beer with those guys! I'd be real quiet and bring the beer too!

[Boz330]

What conclusions did you and your group arrive at? # 1,2,4 and 5 look about the same though differences in the brightness among the six are noticeable.
The thing to concentrate on is the length of the flame on the left hand side of the picture. Remember that it has traveled through 3 inches of barrel before it is visible to the camera.

I told him I thought that they should still try the velocity test with the pellets.

This isn't my project, I just thought that it was pretty interesting, and of course I will have one of these nipples in my Gibbs.

Bob

[Boz330]

That is a very neat test but not sure I see the relevance in how far the sparks go.

See post 6. It isn't about the ejecta but getting past any possible fouling in the passageway to the powder. Firing a 100+ gr powder charge behind a 550gr 45 slug develops a fair amount of fouling compared to a RB gun. Your average time in a match to shoot, clean, reload, and get back into a prone position for your next shot at 800, 900, and a 1000yds is 3 minutes.

Bob

Bob

[nekshot]

just their education and livelihood impresses me! If my caps did what 1thru3 are doing I think that would be good, no? I love this kind of stuff relevant or not. Thanks for sharing it.
nekshot

[waksupi]

I'm not sure what the pictures tell me. I recall Ned Roberts wrote that the coolest primer worked for best accuracy.

[fouronesix]

My shooting buddy, who is on the US long range muzzle loading team, had a terrible time getting good ignition on his Gibbs rifle at a match. The weather was cold and wet.
Bob

I think this is the point about the nipple design and testing- regardless of what Ned Roberts wrote.

[451 Pete]

Boz from the looks of things you guys are giving the old tried and true platinum nipple a good run for its money. As you have said the proof will be in the testing at the range and the wear factor may still remain to be seen. One thing is that with a modern camera and what we have to work with we are now able to see and prove or disprove what was theory in the past, to know not only what works but the why behind it. This should have some very interesting results.

See you soon ... Pete

[GARD72977]

I did not mean this to be disrespectful. Im sure everyone in the group is smarter than I am. I just cant understand how the flame coming out of a 3"bbl has anything to do with accuracy or ignition. I guess I can relate this better to mud grip tires. They get clogged but are able to clean themselves out. I would think the nipple would be the same way. It would need to allow the power of the cap to remove fouling.


See post 6. It isn't about the ejecta but getting past any possible fouling in the passageway to the powder. Firing a 100+ gr powder charge behind a 550gr 45 slug develops a fair amount of fouling compared to a RB gun. Your average time in a match to shoot, clean, reload, and get back into a prone position for your next shot at 800, 900, and a 1000yds is 3 minutes.

Bob

Bob

[Boz330]

Boz from the looks of things you guys are giving the old tried and true platinum nipple a good run for its money. As you have said the proof will be in the testing at the range and the wear factor may still remain to be seen. One thing is that with a modern camera and what we have to work with we are now able to see and prove or disprove what was theory in the past, to know not only what works but the why behind it. This should have some very interesting results.

See you soon ... Pete

Dick has had nipples made up from the same Stainless that the South Africans are using and he has one of their nipples with 2000+ shots on it and it is still within spec. He also used a stainless that these guys recommended for it's gas cutting resistance. And then some made from Inkonel which is some exotic metal used in aircraft exhaust systems.
I'm sure He will be shooting one this weekend. See you Saturday morning.

Bob

[Boz330]

I did not mean this to be disrespectful. Im sure everyone in the group is smarter than I am. I just cant understand how the flame coming out of a 3"bbl has anything to do with accuracy or ignition. I guess I can relate this better to mud grip tires. They get clogged but are able to clean themselves out. I would think the nipple would be the same way. It would need to allow the power of the cap to remove fouling.

Exactly. The flame indicated by the the white, yellow, orange coming from the barrel indicates the power. Which one do you think would have the ability to clear that fowling the best.

Bob

[newton]

I can see the difference. And I do not think that it is just a thing about looks. What I see is a very, very, efficient burning/use of the primer. True, they may all "ignite" powder, but the smaller(hence more brighter flame) the particles that are on fire, the more surface area it is going to ignite.

I get it. No need for a "hotter" primer, just a more efficient use of the ones there are. That's why you don't see so many hitting the paper from the first photo, the primer is effectively being used in the chamber rather than later on.

I am sure there is a better way of describing it, but I am a visual person and the pictures for sure tell the story.

[oldracer]

I am curious about the barrel design they used. As far as I can see, once the ignition starts, there is a very short distance and then the whole ignition gas has to make a 90 degree left turn. Did they take that into account? If we are talking about velocity at all, then higher is worse as it is harder to turn 90 degrees. I am thinking that is one of the reasons "under hammers" may have been popular as the nipple seems to point right at the breech. What I would want is the highest heat and largest amount of heat possible to reach the powder and as I have discovered in my Pedersoli Gibbs starts in the patent breech area.

Oh yes, it is spelled "inconel" (generally 600 series alloys) and we used it to make tubes and the outer shells in Naval reactor steam generators for it's corrosion resistance as it is very hard, wears very well against abrasion but is a tad expensive. I was a Navy nuclear machinist for over 20 years and never though any of that stuff would come in handy.

[Good Cheer]

Isn't the reduced diameter portion of the "patent breech" actually the means of creating a concentrated jet of incandescent gas thrusting into the powder charge for the purposes of reducing shot to shot variability?

[JeffinNZ]

The proof of the pudding will be on the target. I would like to see a 10 shot target comparing the top and bottom nipples.

When you consider the travel of the flame it's quite a big ask. The flame from the cap has to turn a right angle to reach the charge. As shooting progresses fouling accumulates in the path from cap to nipple also. I have a .38cal barrel that is on the back burner in the project queue. I have fitted the drum to the barrel and prior to doing so I increased the diameter of the 'bore' of the drum, coned the front and then polised the channel until it was like a mirror. The theory is the smoother the finish the less friction there is to hold fouling and slow the flame.

Sooooo, back to Ric's comment regarding the coolest primer, I would agree but it's a fine line between having enough ooompphhh to get around the corner and over the fouling to ignite the charge consistently.

[Fly]

My let's keep this stuff simple, Bob for the simple minded as me (Wink).

Fly

[Boz330]

As I pointed out in an earlier post you have an average of 3 minutes to get your shots off. Any shot not gotten off because of a FTF is the same as a miss. If you have to blow the load it could be 2 misses. If you are shooting for grins and giggles (like me) that isn't a big deal but these guys are all on the US Team and take it pretty serious.
The other issue is the burn out on these nipples. Anything over .028 is considered burned out. My copper beryllium nipple was at .031 after less than 200 rounds. If the hole gets too big there have been issues with the hammer coming back hard enough to break it, not a good thing in the middle of a match.
The platinum nipples have been the standard, giving the best wear resistance but they are $60 a piece and there have been instances of the platinum liner blowing out. One guy had one stuck in his forehead. So far 4 of the guys on the Team are using these nipples and early impressions are good. Only time will tell. BTW my buddy who has spearheaded and financed this endeavor hasn't lost a match or had a FTF since he has used one of these nipples. The impetus was the fact that he had so many FTFs at the Oak Ridge match when they had a match in wet weather conditions, something they may have to contend with in South Africa at the world meet in September.

Bob

[lmcollins]

Jeff in NZ:

When you increase the bore of the drum you are decreasing the diamiter of its shank. There is therefore less material to keep it from blowing out?
With the bore increased you are also permitting more preasure on the nipple seat.

Drum and nipple guns need a thick barrel with a small bore out of necessity. Properly made guns with a patten breech have the flash channel drilled at an angle (the flash channel) to the nipple seat.

Just some things to think about. I am not saying that you over did the drum's bore. I'm just stating for the info of others to THINK. Old Quality i.e. higher priced guns, and military guns use a patent breech.

This nipple study business is interesting. Modern science verses old theories. Did those old farts really know what was best?

[451 Pete]

The more that I have been around and shot the old guns the more credit I have to give to the ingenuity and resourcefulness of those in the past that made them. When you think about what they had available to work with, and what they were able to do with what they had, it is really pretty astounding.

Pete

[Boz330]

Amen to that.

Bob

[ShootingSight]

My name is Art Neergaard, I own ShootingSight. I was one of the engineers out with Dick that evening drinking beers (and I drank beers several other nights with him while using little bitty diamond hones to make tiny reamers to develop the internal flow of these nipples). I am a complete novice at anything black powder, but I am a nerd engineer, and I do drink beer. I'm the guy that took the above picture with the 6 nipples. I think perhaps the attached zoom of our nipple before and our nipple after the modification is more telling:

https://dl.dropboxusercontent.com/u/733960/Nipples1.jpg

As you can see the lower (modified) nipple has a much hotter flame. To my thinking, the hotter and bigger the flame, the hotter the gas, the better the ignition. For one, hot gas can negotiate a 90 degree turn better than particulate, which have more momentum (this is why air flows over your windshield, while bugs go splat), and I'm thinking hotter means faster ignition of the powder. I've done a lot of work lightweighting hammers for AR15 and M14 trigger systems. At least in offhand, where I spent time thinking, I imagine that if my swing rate were to continue unchecked in one direction for a whole second, my impact point at 200 yards would easily move over by 10 feet. 120 inchees, call it 100 inches to make easy math. That's 0.1 inches every millisecond. Dick and I are planning to do some high speed testing to measure ignition time, but if the hotter gas shaves a few milliseconds off ignition time, there's your primary benefit. Further, if the hotter flame can get damp powder to ignite more reliably, that's another benefit.

Anyhow, I'll start a different thread, but I'm looking for your help. I am going to fire up a screw machine order for a bunch of nipples, and the cost for doing the setup is the killer, so I want to make as many different nipples as possible. I know the 1/4-28 thread is standard, Dick tells me there is also a metric thread that he will send me ...... how many other funky thread sizes are there on these old guns, civil war stuff, old English construction, etc. I may as well get a few dozen of each made once the machine is running and tooled up. Please don't answer here, look for my new thread.

BTW, we fired these by making a plastic block the size of an AR15 mag. I drilled and tapped 1/4-28 across the top, and screwed in a nipple, such that when we inserted this into an AR lower, the hammer would impact the nipple. So, this is the only AR black powder gun in existence. So this flame has traveled down the length of an AR mag, maybe 2-1/2". Interesting point is raised above, I could modify the holder we made and introduce a 90 degree turn to simulate the actual flame path into a breech.

Thanks,

Art

[Boz330]

Thanks Art that is a better first hand explanation than my second hand info from Dick.

Bob