A reminder to us all not to overlook the obvious

[jonk]

Sometimes you have a load that you know can perform, and you have a crummy shoot. Which happens. Nut behind the trigger and all. But suppose you KNOW, You absolutely KNOW you are doing your part, or even shoot it from a bench and it's still a problem.

I'd break the troubleshooting into 3 steps.

1. Same lube? Same lead? Same powder brand, granulation, and even lot?

2. Fouling. I recently had my musket and carbine both start to open up. I poured boiling water into the musket and let it steep. Normal cleanings aside, you wouldn't believe how much dried caked lube this pulled out of the breech area. Not fouling so much, that was taken care of by regular cleaning. For the carbine, same load I've shot for years, same lube, everything suddenly started leading! While I have to figure out WHY, checking if you have leading is something we should never forget.

3. Mechanics of the gun. If you don't have a fresh nipple to compare your old nipple to... get one. A nipple that is starting to erode might, shoot after shoot, "look" good compared to last time, but much like we all don't LOOK older in the mirror from day to day, over years, we do. Same for a nipple. It might be more eroded than you realize, even if it looks good on it's own; it doesn't take much erosion to change point of impact and/or open a group. You might also check for a semi-plugged flash channel, wood that is suddenly impinging on the barrel, or what have you. I have one musket I shot for 2 years no issue, it got wet, and even after drying I had to sand out the barrel channel to relieve where suddenly the wood was real tight against a band. Also the sights! A flip sight (that many of us use)... more than once I was asking, "Why is this gun going HIGH suddenly?" Shoot after shoot of sight black had built up and the leaf wasn't folding down all the way....

I just thought that these were tips I have noticed that any newbie could consider, and the rest of us shouldn't forget. Feel free to add to them! :)

[Rob FreemanWBR]

I've heard that some caps are "hotter" than others... As such, some skirmishers claim that this "variable" changed their point of impact noticeably.


Personally I've found differing powder lots to be one of, if not the leading culprit. Next would be hard lead (esp. for Minie balls) and all the wonderful "key holes" those particular rounds make - if the round even hits the card board backer!


My observations/two cents.

[jonk]

Those are good ones, Rob. The heat of a cap certainly does vary a lot from brand to brand, and even lot to lot. I had one lot of RWS caps that were weak, weak WEAK. When usually those are fine. You could even see in the cap that there was less priming compound than normal. Worked fine on smoothbore, and on an enfield; wouldn't work reliably with a springfield with the angle that the flash has to make, to say nothing of a breechloading carbine (sharps or smith).

Hard lead... absolutely. You can get your lead from Fred or somone you know is solid in terms of their quality, or you can get a lead hardness tester. I've seen batches I could scratch with my fingernail, or even squeeze the base of a cast minie, but it was like 20:1 in hardness. Soft enough that some shots went just fine, some flew. Never had any that was hard enough to tumble, but it certainly can happen.

[Michael Bodner]

Regarding caps - How they seal to the nipple will/can greatly affect pressure, and thereby, velocity and performance.

-Mike

[Rob FreemanWBR]

From what dad & many of the Blues have taught me from day one: CONSISTENCY is key with regards to obtaining and maintaining accuracy in this sport.

Given the potential for affecting POI, I "bite the bullet" (sorry I couldn't resist) and buy my Goex powder one or two kegs at a time, ensuring both have the SAME lot number.

Ditto for caps - when I resupply, I do so in bulk. Each time I do however, it's amazing (if not disappointing) to see the dizzying rise in price for caps since my previous bulk buy; even more so when looking way back to the early '80's...

As for lead, I use the cost friendly and time tested Clink-Clunk-Lead Test. Dropping ingots onto a cement surface, if they make a "clink" sound, they're hard. Making a "clunk" tone, they're used for minies and revolver rounds. Its never failed me to this day, and if needed I also have the back up tester - my thumbnails. Last but not least, when in doubt - I just cast the suspect lead ingot(s) into smoothbore or carbine projectiles....

[Eggman]

Regarding caps - How they seal to the nipple will/can greatly affect pressure, and thereby, velocity and performance.

-Mike
A most interesting assertion. How exactly did they measure the back pressure escaping through the nipple? How were they able to isolate the cap effect on pressure/velocity vs. variations in propellant pressure and/or bore resistance (as per fouling)? Did they examine the variations in pressure due to the cap sealing vs. not sealing (sometime the cap welds itself to the nipple, other times the wings flare out)? And finally who did the research? Has it been published somewhere in such a way that we can duplicate the tests?

[jonk]

As regarding back pressure escaping through the nipple depending on cap fit...

Even the guns I have that have fairly soft sear springs don't re-cock when you fire the gun. Even using original style nipples with the big holes, like my Potsdam. This tells me that fairly little pressure is actually escaping the nipple.

Additionally, even when the nipple is a little fouled up and seating a cap is sticky, the hammer drives it down just fine. While I can appreciate that this might lead to delayed ignition, or faulty ignition of a weak sear spring is involved, the cap still gets sealed to the nipple.

I have seen caps do different things. Sometimes they look almost unfired. Sometimes they shatter. Usually they flare out a bit, along the wings. What you don't generally see though is the top part of the cap get punctured, which would happen if any serious pressure were escaping via that route.

I have fireformed enough cases to know that even on a comparatively thick cartridge case, if you don't have at least 8-10,000 psi, the case won't fire out and fireform. Given that a percussion cap is a lot thinner, the fact that it doesn't form to the shape of the hammer face suggests to me again that very little pressure is leaving the nipple.

I guess the point I'm driving at is, while I don't disbelieve the idea that nipple to cap fit is important, if it is, it's more for quick ignition and positive ignition, and less so to maintain consistent pressure, because the pressure involved seems pretty weak.

[Eggman]

As regarding back pressure escaping through the nipple depending on cap fit...

Even the guns I have that have fairly soft sear springs don't re-cock when you fire the gun. Even using original style nipples with the big holes, like my Potsdam. This tells me that fairly little pressure is actually escaping the nipple.

Additionally, even when the nipple is a little fouled up and seating a cap is sticky, the hammer drives it down just fine. While I can appreciate that this might lead to delayed ignition, or faulty ignition of a weak sear spring is involved, the cap still gets sealed to the nipple.

I have seen caps do different things. Sometimes they look almost unfired. Sometimes they shatter. Usually they flare out a bit, along the wings. What you don't generally see though is the top part of the cap get punctured, which would happen if any serious pressure were escaping via that route.

I have fireformed enough cases to know that even on a comparatively thick cartridge case, if you don't have at least 8-10,000 psi, the case won't fire out and fireform. Given that a percussion cap is a lot thinner, the fact that it doesn't form to the shape of the hammer face suggests to me again that very little pressure is leaving the nipple.
I guess the point I'm driving at is, while I don't disbelieve the idea that nipple to cap fit is important, if it is, it's more for quick ignition and positive ignition, and less so to maintain consistent pressure, because the pressure involved seems pretty weak.

Excellent, well thought out post. My interest in caps doesn't go much beyond can I get it on the nipple, will it fire the gun, can I get it off. I go RWS any way I can get them. Where real attention needs to be paid is nipple condition. You need a really teeny tiny little hole in the bottom, but still able to fire the gun (and on the other end get the cap on and off). The tiny hole keeps down velocity variations because you're not firing the gun out of both ends.

[John Bly]

Have you ever wondered why military muskets and carbines have such heavy hammers and thumb buster mainsprings? Is all that necessary to set off a percussion cap? Could there be other reasons for it? Just food for thought.

[jonk]

Have you ever wondered why military muskets and carbines have such heavy hammers and thumb buster mainsprings? Is all that necessary to set off a percussion cap? Could there be other reasons for it? Just food for thought.

It's good food for thought, as is the realization that back in the day, caps were generally a bit thicker than today... meaning those heavy springs were needed to reliably set them off.

I have (as my original post indicated) seen enough evidence that even mild erosion of the flash hole in the nipple can cause groups to shift and/or widen. What causes that to happen is a debate in and of itself. Is the increased flash hitting the powder forcing the powder column forward, before it ignites? Is some additional pressure now escaping the nipple itself? Or both? Or is the extra spark now hitting the powder igniting it faster, changing results? We'll probably never know. Whatever the reason, it comes back to consistency. I think you can probably work up a good load with a nipple of ANY diameter touch hole, whatever your spring strength may be (so long as it reliably touches off the main charge that is). But, just like in cartridge reloading...where a different primer can change things radically... I think that changing the diameter of the flash hole, either intentionally or by erosion, is akin to increasing or decreasing the heat of the primer, and as such, yields different results.

Let's take an example. My main skirmish musket is a fayetteville repro with a hoyt barrel. It's favorite load is 48 gr of goex 3f, with a hodgdon bullet, and small diameter nipple. When that nipple starts to erode, groups open. As I said, WHY they are opening isn't material, that they ARE is the main problem. But to follow my suppositions to their logical conclusion, one of two things would be true.

1. If the eroded nipple is letting more flame hit the charge, a smaller charge would restore accuracy, for a time.
2. If the eroded nipple is letting more pressure escape via the breech, a higher charge to offset that would be in order.

Now I keep a supply of small hole nipples on hand to address this issue when it happens. Which is usually about once a season, that I change them out. But I keep the old ones in a baggie in my range box as spares, assuming the top of it isn't getting peened down. It would be a fairly easy experiment to try some higher/lower charges with those shot out nipples, to see if one of my suppositions is true.

It seems a good off season project to me! :)