nipple orfice erosion

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M. De Land

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I've not done any real testing to confirm how eroded nipples effect accuracy but have suspicion-ed as well as read of it's deleterious connection. I'm wondering if any of you have had experience with this?
I suspect this is the cause of a sudden accuracy drop in my underhammer match rifle. I have some new nipples coming so will get a read on it soon in this rifle.
 

SDSmlf

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Personally I have found that as the nipple orifice wears and opens up from factory .028” diameter to about .035” accuracy and POI are impacted, particularly when shooting paper patched conicals at longer distances. Somewhere past .035” orifice diameter (don’t have real data as I don’t typically don’t let nipple orifices go last .035”) I have experienced the hammer going to half cock. I toss or give away any nipples (plenty of knuckheads out there seem to want them) once the orifice opens to or beyond .035”.
The heavier the bullet (conical vs roundball for example) and the heavier the powder charge, the quicker the orifice enlarges. Shooting 400-500 grain conicals in a 45 caliber gun over 80 to 100 grains of 3F can open a new nipple up in well under 50 shots. With a target gun shooting lighter roundball loads the nipple life should be greatly extended.
 

hanshi

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SDSmlf makes some good points. I don't shoot conicals so have not had this problem. I will say that stainless nipples, like stainless liners hold up to erosion much better.
 

Artificer

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I've not done any real testing to confirm how eroded nipples effect accuracy but have suspicion-ed as well as read of it's deleterious connection. I'm wondering if any of you have had experience with this?
I suspect this is the cause of a sudden accuracy drop in my underhammer match rifle. I have some new nipples coming so will get a read on it soon in this rifle.
Funny you should mention nipple problems in your under hammer rifle.

Shortly after I was asked to be the Team Armourer for the U.S. International Muzzle Loading team, I attended a preparatory meeting for the World Championships in 1996. I had many years of working guns at the Spring and Fall Nationals of the North South Skirmish Association as well as having been a Team Armorer for Nationals using unmentionable rifles. So I made up an "Armorer's suggestion sheet" for the Team prior to leaving for the World Shoot.

I can't even begin to think of how many times I've seen eroded nipples cause accuracy loss; mostly in NSSA Rifle Muskets and Revolvers, but also with standard rifle nipples that were shot in competition. So I most strongly advised the percussion shooters to have TWO brand new nipples for each gun and that both caused the same group size and placement of group. That way if the nipple went bad at the World Shoot, they could instantly change it and get right back in the competition.

Actually, I strongly suggest putting a new nipple on a gun when you put it up for the winter, after a season of shooting. That way you will have a fresh nipple every year. Now if it is just a hunting rifle you don't shoot much except in BP Season, then at least every three years replace the nipple, before it causes an accuracy loss.

OK, so we are at the World Championships in Wedgnock, UK and I am set up best as I can on my picnic table work bench and vise already C clamped to it. I laid out a bunch of Original and Repro Musket tools each day, just outside my common working tools. I did that for speed in case someone needed a nipple changed and for them to use in case I had to use the necessary or was "walking the line" while my Team Members were shooting.

About 10 AM, I made a trip to the Necessary and when I got back, our best Female Shooter was frantically going through the nipple wrenches during the second day of practice. She was the wife of the of a very good friend of mine and we were also very good friends, besides. As I walked up I calmly asked, "Nancy, what seems to be the problem?" She had her original .45 caliber Underhammer Rifle with which she had won two gold medals at World Championships with in the past, plus other medals earlier in her career. I KNEW that rifle would shoot extremely well. So when she described how the group size had gone to Heck, I looked at the nipple and sure enough it was eroded too much.

However, BECAUSE it was an original rifle, I was a bit worried about the nipple thread size not being of a modern standard size. So I told her I would take care of it and suggested she get a cup of coffee or tea while I worked on it. FORTUNATELY, it had been re-threaded for the modern standard 1/4 x 28 I found when I got it out and checked the thread size. So I quickly got a new nipple installed. (I found out a couple days later a good friend of both of ours had re-threaded it for modern nipples about 4 years earlier.) I was just about finished checking everything else on the rifle when she came back with her coffee. As I finished, I informed her everything was fine with "her Baby" and she should now be able to shoot good groups.

HOWEVER, then I noticed she had laid out the little plastic/glass vials that held individual powder charges for her rifle on the 2x4 horizontal beam that supported our overhead plastic fly. She had done that to count how many she had left. The sun shone right through them, or I may not have noticed. I could EASILY see the powder charges were different by eyeball alone. It took a few minutes to explain she had to have done something wrong when measuring the charges and she had to separate and empty the ones that were different.

OK, we got that corrected and off she went to shoot. She came back later on that afternoon and said her rifle was right back to shooting as good, if not better than new. Now BECAUSE she was a long time personal friend, I asked her, "Nancy, you were in the meeting when I discussed changing nipples before we came here, what happened?" She admitted her rifle was still shooting well with a nipple the other shooter (the one who had re-threaded it to standard size) had replaced in the rifle 1 1/2 years before, so she thought it would be OK. I rolled my eyes and she said, "Yeah, I know...."

She wound up with the Silver Medal for the Ladies 100m shoot that year. Unfortunately the rifle that beat her belonged to the Wife of the Swiss Team Captain and I had resurrected that rifle a few days before. Nancy wasn't real happy with me for that.............Grin.


Gus
 

FishDFly

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My Mentor would shoot a lot each year.

His ritual was to go buy new nipples for each of his M/Ls' after Christmas.

New Year's Eve he would stay home and put a new nipple in each one.
 

ohio ramrod

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As others have stated, shooting heavy conicals with heavy powder charges will erode a nipple faster than shooting prb with lower powder charges.I shoot mostly low powder charges with prb and get close to 1000 shots/nipple. But I know people who shoot heavy charges with conicals who get less than 100 shots/nipple. Top of the line English sporting rifles used platinum lined nipples to reduce the eroding. At today's prices for platinum it is easier to just change the nipple.
 

52Bore

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Nipple erosion was discovered soon after Whitworth’s experiments, I believe.
Platinum lines nipples are still seen/survived on high end arms, mainly British work.
A very interesting one from a William Moore.

E2C9E411-3ECF-4A13-87FB-1475F1C0BC6F.jpeg
 
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necchi

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I've not done any real testing to confirm how eroded nipples effect accuracy but have suspicion-ed as well as read of it's deleterious connection. I'm wondering if any of you have had experience with this?
Oh Yeah, it's real alright.
Many times referred to as "Gas Cutting". There are multiple topics of the subject to be found in the archives of this forum. It also happens to the flash-hole of flintlocks.
As mentioned, how quickly it happens depends on the load, charge and care of the nipple.
All that pressure and heat of exploding powder and result hot gases that pushes the projectile forward in the barrel is exerted against that tiny hole in the nipple,, the only reason it doesn't come out the back of the barrel is the hammer being held by a spring against the top of the nipple,, but some leaks out every shot. We've all seen or experienced hammer blow-back in our learning process.
Long story short, with my rifles and loads, I get around 400 shots before the groups start to open. For an active competition shooter that does weekly practice, and with an event that can be 50-100 shots per day,, it doesn't take long to burn out a nipple.
 

M. De Land

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Some times I wonder about myself ! Every time I clean that rifle I take a look at the orifice and as long as it looked round I didn't notice the enlargement until it wasn't giving me hits I was holding for, having long since learned to call my shot. This became increasingly evident when the bench portion of the match came up.
I was getting increasingly suspicious of the flyers in offhand shooting that had no relation to the shot break positioning but kept writing them off as flinch or patch material switch.
While cleaning after the match I noticed an elongation in the orifice for the first time and when I matched the orifice diameter to a new nipple the light came on. It was nearly half again as large and had it not been irregular I would probably still have thought all was fine.
Boy I hate being stupid! After the enlightenment though, it gives me a good laugh ! 😄
 
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nkbj

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I haven't figured it out but look forward to spending the time on the range.
Right after I outsmart the ******* bambis eating my garden.
 

ord sgt

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At my home range, a guest shooter was complaining that his T/C Renegade was shooting poorly. He was trying to check his rifle before the opening of hunting season. I checked the nipple and suggested that he change the old one out for a new nipple. The next week, he was back and all of his shots were in a tight group. Big smile from the guest. Never did hear any more from him.
 

LME

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Oh Yeah, it's real alright.
Many times referred to as "Gas Cutting". There are multiple topics of the subject to be found in the archives of this forum. It also happens to the flash-hole of flintlocks.
As mentioned, how quickly it happens depends on the load, charge and care of the nipple.
All that pressure and heat of exploding powder and result hot gases that pushes the projectile forward in the barrel is exerted against that tiny hole in the nipple,, the only reason it doesn't come out the back of the barrel is the hammer being held by a spring against the top of the nipple,, but some leaks out every shot. We've all seen or experienced hammer blow-back in our learning process.
Long story short, with my rifles and loads, I get around 400 shots before the groups start to open. For an active competition shooter that does weekly practice, and with an event that can be 50-100 shots per day,, it doesn't take long to burn out a nipple.
I found out that nipples burned out way before I read about it. It does make a difference!
 

JCKelly

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To resist hot gas erosion stainless is better than hardened carbon steel.
TOW lists "stainless" nipples. There are a zillion alloys that might be called "stainless"
But they must be cheaper than platinum lined.
(retired "stainless", &c, metallurgist)
 

M. De Land

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I found out that nipples burned out way before I read about it. It does make a difference!
I've always known about nipple erosion but for some reason had the notion that it always manifested in irregular elongated orifice shape. If it looked round I had the false idea it was not eroded to any great extent. It wasn't until last months match where we had two bench portions of the match at 50 and 100 yards that I realized I had lost the accuracy this rifle had always demonstrated. The rifle still shot well at 50 yards but at 100 yards I was getting shots out of the black that would not have occurred when the rifle was new. I saw some evidence of it at the same ranges in off hand but did not associate it with the nipple erosion. It wasn't until I cleaned the rifle after the match and saw some elongation of the orifice and then compared the diameter to a new nipple that the light came on.
The other thing is I knew if a nipple was eroded it would usually show up in the hammer being kicked back which this rifle did not do so I went on my merry way in ignorance thinking I just needed to hold better.
Pretty dumb for an experienced shooter, I must admit !
 

LME

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I've always known about nipple erosion but for some reason had the notion that it always manifested in irregular elongated orifice shape. If it looked round I had the false idea it was not eroded to any great extent. It wasn't until last months match where we had two bench portions of the match at 50 and 100 yards that I realized I had lost the accuracy this rifle had always demonstrated. The rifle still shot well at 50 yards but at 100 yards I was getting shots out of the black that would not have occurred when the rifle was new. I saw some evidence of it at the same ranges in off hand but did not associate it with the nipple erosion. It wasn't until I cleaned the rifle after the match and saw some elongation of the orifice and then compared the diameter to a new nipple that the light came on.
The other thing is I knew if a nipple was eroded it would usually show up in the hammer being kicked back which this rifle did not do so I went on my merry way in ignorance thinking I just needed to hold better.
Pretty dumb for an experienced shooter, I must admit !
Your post read like you were reading my mind?
 

M. De Land

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I've always known about nipple erosion but for some reason had the notion that it always manifested in irregular elongated orifice shape. If it looked round I had the false idea it was not eroded to any great extent. It wasn't until last months match where we had two bench portions of the match at 50 and 100 yards that I realized I had lost the accuracy this rifle had always demonstrated. The rifle still shot well at 50 yards but at 100 yards I was getting shots out of the black that would not have occurred when the rifle was new. I saw some evidence of it at the same ranges in off hand but did not associate it with the nipple erosion. It wasn't until I cleaned the rifle after the match and saw some elongation of the orifice and then compared the diameter to a new nipple that the light came on.
The other thing is I knew if a nipple was eroded it would usually show up in the hammer being kicked back which this rifle did not do so I went on my merry way in ignorance thinking I just needed to hold better.
Pretty dumb for an experienced shooter, I must admit !
Here are the two nipples compared side by side. The burned out one and a new one.
IMG_2128.JPG
 

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