Underhammer flintlock mechanics

[Larry Pletcher]

For some time I've been curious about underhammer flint guns.  Below is a pic I saw recently.  I'm puzzled by the mechanics.  I don't see a main spring unless the pivoting sear is it.  Also I don't see how the frizzen is held closed.  Could the flat bar above the plate be a frizzen spring?  Any thoughts?

[Metalshaper]

Larry,

 Look under the light feather spring, that holds the sear bar in its position. I believe there is a heavy mainspring underneath it, pushing down on the rear of the hammer?

 also look at the area above  the frizzen/pan. there is a light spring that is riding along the top of the plate.( in the pic ) I also think I see a small spur from the frizzen, just poking up above the plate and holding the extreme left edge of that spring up??  that would be the frizzen sping??

at least that is how I see it and how I've redrawn a Metalshaper/Dagwood version 

Respect Always
Metalshaper

[Metalshaper]

Larry,

 Look under the light feather spring, that holds the sear bar in its position. I believe there is a heavy mainspring underneath it, pushing down on the rear of the hammer?

 
Actually that mainspring is pulling/pushing  upwards?? on the rear of the hammer

[lew wetzel]

it seems it would have to be one very fast release and ignition as you would think the powder would fall out or not get a good burn....looks pretty cool but is it practicle.must not be or you would see alot more of them...

[Larry Pletcher]

it seems it would have to be one very fast release and ignition as you would think the powder would fall out or not get a good burn....looks pretty cool but is it practicle.must not be or you would see alot more of them...

Most locks work surprisingly well up-side-down.  In the time it takes for the mechanics to work, the powder only has time for fall 1 mm or 2 -- directly into the sparks being driven upward.  The link below is to a page on my web site where you can see a large Siler firing up-side-down in slow motion.  the quote below is from the site and sets up the video.  There are 2 video screens on the page; the one you want is the lower one.

"Part B includes a pair of high speed videos of a large Siler lock firing up side down. The lock is tried with chipped English flints bevel up and down. Swizz Null B is used in both trials. "

http://www.blackpowdermag.com/featured-articles/ultra-high-speed-flintlock-movie.php

If you are on a dial-up connection it will take a while to load.  Cable or DSL connections work well.

[lew wetzel]

larry,just watched your videos and i have to say that is pretty impressive..you guys do some of the coolest stuff..

[Gene Carrell]

Soo I could be hanging upside down from my treestand and still get the shot off!

[don getz]

I know it is always fun to shoot a flintlock upside-down, just to prove that it can be done, but why in h____ would you
want to build one that way.  Some guys do it just to prove it can be done, but it sure is ugly......Don

[C Wallingford]

Don--
I agree, it sure is ugly. Unique but ugly.

[David Rase]

I have always been fasinated with the under hammer flintlock mechanisim.   I think my fasination comes from the tinkerer in me that likes to build one of a kind objects.  There is enough information in the picture that I could see myself building a copy of that action just for the challange.  Don't have a clue what I would do with it once it was built but that has never stopped me before. 
DMR

[sluggunner]

At our Ohio State Championships last weekend a fellow showed up with an underhammer flintlock fowler patterned after the one that you show. He made the lock himself and said that he substituted a coil spring for the main spring. Didn't see the lock out of the rifle so I don't know how he managed the frizzen spring but I suspect it is as Metalshaper says. I talked with him some and he was quite pleased with the lock speed and reliability and said he gained great respect for the flash when shooting offhand. Got burned a time or two.
                                                                        Rich

[D. Taylor Sapergia]

I'm with you David.  I've admired that particular rifle ever since I opened that book the first time.  And I have always wanted to replicate it, too.

[Larry Pletcher]

Thanks for all your comments.   For me the reason is my curosity for how things work and what can I learn.   I first looked at the drawing and wondered if I could time it.  After watching the large Siler up-side-down perform perhaps even faster than it did right-side-up,  it makes one wonder. 

Taylor, David, if either of you make such a critter, I want to hook up the interface and time it.  It would mean designing a new fixture to fire off the trigger, but I have already begun a fixture to do that.

[Dale Halterman]

Didn't the Bevel Brothers do some test firing flintlocks upside down a few years ago? My recollection is that they worked fine but burned the shooter's fore arm. That would explain why they weren't more popular.

Dale H

[David Rase]

I'm with you David.  I've admired that particular rifle ever since I opened that book the first time.  And I have always wanted to replicate it, too.

Taylor/Larry, Which book is is the picture take from?  I don't recall. 
DMR

[Metalshaper]

Herschel Logan's
A pictorial history of the Underhammer gun

Respect Always
Metalshaper

[northmn]

I am enough of a tinkerer to understand your desires and just want to comment on the picture of the original.  First look at the trigger in relationship to the comb.  It appears like the wrist is longer and the grip area is far back.  Underhammer percussions were never real popular either although many target shooters liked the faster ignition.  Burning the forearm could be disconcerting.  Funny thing about some designs is that ascetics have often overruled function.  Who knows?  The 45 1911 is claimed to be one of the worst ergonomically designed hanguns made.  The m16 is about the best with its straight back recoil but puts a lot of folks off.

DP 

[Daryl]

Taylor and David - I-too would like a copy of that rifle pictured above. I think it's very cool!  Flat sight plane, no whoof in the face every shot - would be a boon to new flint shooters, I think, not having the flash in front of the eye. Too, without a cheek piece it would be ambidextrous. As to the burning of the forearm - no problem- just stitch in a soft leather patch on the sleeve to cover that part that gets hit - just like my old, Elmer's sitting position shooting pants had inside the knees to prevent lead splinters and cylinder/forcing cone blow-by from cutting up my legs. Problem solved.

[Daryl]

Further to my last post, with the vent in the bottom middle of the pan and therefore with most of the flash go straight down, one might wish to have a slight angle to the vent aimed to the offside of his shooting arm - or - learn to shoot with an outward bend in the elbow?

[Long John]

I think it is an intriguing design.  But as I pondered it I discovered that there are some "issues" with it. 

The first is that it causes the barrel to be moved forward relative to the trigger compared to more common guns.  That will adversely affect the balance considerably. 

The second it that we commonly take the lock off the gun to clean it.  The vent is right there on the side of the gun, permitting easy access.  In this design the vent is up inside the gun with stock wood all around it.  That would make cleaning a bit more of a chore.  It would be more weather-resistant, though.

The third is that the priming powder is going to be some distance from the main charge.  There is a projection extending upward from the frizzen that I presume is a flash channel that butts up against the bottom of the barrrel where the vent is.  Even with a White Lightning vent bushing, I would expect this arrangement to be slower that a conventional sidelock.

Finally, with this design there is lock work where the end of the ramrod ought to be!  Consequently the ramrod hole would have to be drilled off to the side.

Those issues might have been compelling enough to prevent the idea from catching on.

Best Regards,

John Cholin