Multiple flashes in the pan failure to fire

[AZshot]

Yesterday afternoon I had trouble firing a load for about 30 minutes.  This has never happned to me in many decades of shooting black powder, admittedly most in percussion guns.  I had my 45 cal Don Bruton rifle, and had shot 2 times with no problems.  Using 45 grains of FFF and the same powder in the pan.  In the past I've used FFFF in the pan, but I ran out.  I use a patched moist with a water and ballistol for lube. 

The first misfire (flash in the pan) I realized I didn't pick the vent prior. I usually do. So I did for a second try, and just reprimed the pan.  Another flash in the pan.  So next I wiped the frizzen face, and the pan and lip of the flint.  picked the vent all the way into the powder as far as the pick would go, moved it around to make a channel like I do.  Flashed. 

The next 2-3 times I trickled powder into the vent, pushing it inside with the pick.  Not much would fit of course, the gun was loaded.  The flashes became weak or I would get a Klatch and no powder would fire.  So next I reversed the flint.  2-3 more shots, flashes in the pan. 

Next I got my last new flint out of the bag, put it in the hammer.  Cleaned the pan and face well, and spent about 10 minutes getting as much powder in the vent as I could.  Then used the pick to crush a channel again through the powder.  Another flash in the pan.  After 1-2 more tries, I got it to fire with a distinct delay....fffffsss-booom!

Each time I used a half to 2/3 pan full primer, and kept it below and slightly away from the vent.  It's dry in Arizona, and was about 65 degrees.  I was about to think I'd need a worm, somthing I've never had to do in 40 years. 

What would have caused this refusal to fire?

[rich pierce]

I’d get a scraper jag and scrape the breechplug face. There’s a good chance you have a fouling cake issue. A good worm will also work. Plug the touch hole and let water stand in the barrel then empty it and scrape it to be sure it’s all clean. When finishing up cleaning make sure you feel the air really blast out of the touch hole easily when running a patch up and down.

[smylee grouch]

Can we assume you have a vent liner in the rifle?  I always place prime UP TO BUT NOT COVERING THE VENT. Like Rich said, a good cleaning/scraping won't hurt anything.

[AZshot]

Thanks both.  I've never scraped the breach, it's about 4 years old, has maybe 100 rounds shot.  It does not have a vent plug, Don doesn't build them that way.  It's just a coned touchhole.

[MuskratMike]

I've seen this before but never on a Don Bruton gun. Take a 1/16 drill bit and run it into the vent hole making sure not to wallow out the hole. I suspect there is a small piece to metal partially obstructing the hole.
"Muskrat" Mike

[D. Taylor Sapergia]

Enlarge the vent to about .070" with a number drill.

[L. Akers]

With much respect to Taylor, I would not enlarge the vent. I would try banking priming powder against the vent after scraping the breech face to eliminate any problem there.  High speed photography has proven that banking powder against the vent results in MUCH more fire inside the breech than having the vent clear of prime.  Manton cupped the outside of his vents to "... admit a larger quantity of powder across the joint of the lock...".  An internal vent cone should be such that powder granules of the main charge are visible at the vent opening

[Daryl]

The only time I had miss-firing trouble like that, was when the vent and breech was full of oil in my .32 SMR. Foolishly stored it butt down at Hefley Creek Rondy.

[AZshot]

I've checked the vent and it's clear, and was when I kept trying to fire it in the field.  I could get a pick in there, and I felt powder crunching with it.  After cleaning it I have checked the vent again, and just now.  I put a metal pick in the hole, and put a metal cleaning rod all the way down the bore.  It went against the pick and made it move a good bit, just touching it with the rod.  So that tells me there is a "hollow" behind the vent of at least a quarter inch.  I assume that is how it should be. 

I don't think it could be oil contamination, I had fired twice already.  I'm left with either bad powder, or maybe carbon buildup that is now gone after cleaning.  I can say it was pretty frightening to fire 10 shots without lighting off the charge...I was very glad when it finally went off.  Didn't relish the thought of bringing home a loaded rifle and messing with it....loaded.

[AZshot]

L. Akers, thanks for the tip about banking the powder.  I'll experiment with that next time I take it out.  I'd always heard "keep the hole clear", but who knows?  I'll try!

[Hank*in*WV]

I,ve also had this problem in the past. After trying most of these remedies with no success, I've run the rammer down the barrel again, tamping it hard. Afterward the rifle would go off. I don't have any reason why, but who cares if it works.

[Habu]

I had one gun (an old Ketland fowling piece IIRC) that would do this.  I learned that if I plugged the touchhole with a feather before loading, it didn't happen.  My idea was that when I removed the feather, it left a "hole" into the compressed powder leaving lots of surface area for the pan flash to ignite. 

Since then I've continued the practice with all my flinters and seldom have a flash in the pan. 

[alacran]

I do most of my target shooting in AZ. The few times I've had a flash in the pan, seemed to be caused by a crud of burnt primer in front of the touch hole.
When I started shooting flintlocks there was a common misconception of filling the pan halfway and banking away from the touch hole.
I read Pletcher's study on this on Muzzle Blasts when it came out. Larry Akers explained the principle in his post. I just fill the pan full of prime and seldom have a flash in the pan.
There were a lot of "Buckskinner wives' tales" that Larry Pletcher has debunked.

[Leatherbark]

I have seen guns made with the touchhole about an 1/8 inch in front of the face of the breech plug.  As a matter of fact there are guns out there that have a groove cut in the face of the breech plug where the touchhole is so close. These guns would start to fail to fire after 10 or so rounds because of ash build up blocking the touch hole.

Bob

[Bob Gerard]

Isn’t 1/4” (or more) kind-of a big space between breech face and the touch hole? It might be the vent is aligning with the front of the charge rather than towards the rear of it.
Among other things, heavy lube from the patch may dampen the powder it seats against.  If your touch hole is that far towards the front of the charge, your damp powder might be at the vent hole and what is causing ignition failure or delay. One way to check this is to add some filler such as corn meal over the powder charge and then seat the ball. That will keep patch moisture from contacting the powder.
Just a thought.

[AZshot]

When I said about a 1/4 inch, that was a guestimate, not acutal measurement.  I just was pointing out that there was no carbon buildup blocking the hole.  This is a Colerain barrel, the rifle made by a very experienced long rifle gunsmith.  I'm sure it was set up right.   I'm going to try to use more, not less, priming powder next time. 

Here is what I think happened.  Again, just guessing and using my experience as an engineer.  I think for whatever reason the first shot didn't light the charge.  A fine coating of soot covered the pan, and also went into the hole a little.  The next flash, and all the subsequent ones, just kept adding soot into the hole.  As I picked and made a channel I could feel it getting more constrained in there.  Part of that was the grains of powder I was trying to push in (without my reading glasses).  But part was unburnable "soot" that was blocking the flashes.  Finally I got enough powder in there, taking my time to actually get about 3-4 grains weight in there.  When it fired that time, it was enough to get past the sooty powder that was refusing to light.  Possible?  Who knows. 

[rich pierce]

Hopefully a rare occurrence!

[Pukka Bundook]

AZ,
I don't think anyone mentioned bumping the butt on the ground to settle the charge, (or rapping the stock with barrel pointing up)
before loading the patched ball.

This usually prevents a hung up charge.
You will know this most likely, but thought I'd mention it.

[Kurt]

I had a very similar experience this past summer after changing a touchhole. I believe it was caused by a less-than-clean breach- in my case. It also inspired me to measure the depth from the breach plug to the touch hole and I was surprised at the volume there. 45 grains of fine powder might be shallow.

[AZshot]

Yeah, I know it's a light load, but it shoots accurately and I'm not hunting.  I do settle the charge, and seat moderatly firm.  I suppose there is a chance THIS is the problem!  The patched ball was basically at the hole.....I'll do some measurements and up the charge some to be sure. 
Update: I just measured my charge of powder.  45 gr will fill a bore of my diameter about 1 1/2" tall.  So I think the ball would be at least 1" above the touchhole.

Thanks for all the good comments.

[Daryl]

I do most of my target shooting in AZ. The few times I've had a flash in the pan, seemed to be caused by a crud of burnt primer in front of the touch hole.
When I started shooting flintlocks there was a common misconception of filling the pan halfway and banking away from the touch hole.
I read Pletcher's study on this on Muzzle Blasts when it came out. Larry Akers explained the principle in his post. I just fill the pan full of prime and seldom have a flash in the pan.
There were a lot of "Buckskinner wives' tales" that Larry Pletcher has debunked.

Same here - fill the pan to catch as much of the sparking as possible. That way, it will never be banked anywhere - always perfect. I've got lots of 4F - comes in a 1 pound can. If 5 gr. constitutes
a pan full, that's 1,400 shots to the pound of prime.

[Darkhorse]

I have to agree with Taylor, enlarge the touchole to .070, my .40 is at .062 but I always enlarge my main hunting rifles until I get the speed and consistentcy I want.
I use only number drills and go up one at a time on the range, shooting several shots at each size until I get the result I'm after. There is no rule saying a TH must be 1/16".

[AZshot]

It's fired consistentaly for 2 years with the current hole size.  Something else has changed.  I don't want to do a fix that isn't needed. I need to figure out the root cause first.

[Blacksmoke]

 I agree with Taylor - enlarge your touch hole.  Even .080" is not to big.  One other thing you could do is to create a small chamfer on the beginning of the touch hole which will act like a tiny funnel. This will help to collect the pan flame to the hole.   Hugh Toenjes

[AZshot]

I just measured my touchole, it's .067 or a little larger.  I've had very reliable ignition with it until this last outing.  It's something else.