Lock speed; percussion vs flint

[Col. Batguano]

I realize Pletch did a quite a number of very good HS videos some years ago showing the difference in lock speed with various powders, locks, etc. As I recall, the fasted=st flint locks set off the pans around .045 seconds, and the fastest percussion locks were around .030 seconds.

My question here is regarding the relative difference in time it takes between priming ignition, and projectile exit (lets assume equal muzzle velocities and equal barrel lengths, as, we also know that a flint lock load needs to be about 5% greater than a percussion load to achieve the same MV.

Intuitively speaking, it would seem that the pan flash has to burn up and reach a sufficient strength before the fire can work it's way through the touch hole to set off the main charge. The main charge burns, builds pressure, and shoots gas out the touch hole until the gas can't escape any more, and then the ball is started on its' way.

With a percussion gun once the cap goes off most all of that flame is directed through the nipple right in to the heart of the main charge. Just like with a flint gun, there's pressure push back against the cap, cock and nipple, but that is much more tightly sealed in a percussion gun than the open hole in a flinter, so the ball seems like it ought to start on its' way faster too.. Intuitively, the charge consumption process seems like that too ought to be faster in a percussion gun than a flint gun. Have tests been done to measure total elapsed time from sear trip to ball exit between the 2 systems (all other variables adjusted to be constant)?

I'd be curious as to the findings if they do indeed exist. That is, my hunch is that lock speed is only PART of the reason a flinter is inherently less accurate than a percussion gun.

 

[hanshi]

I agree. The prime of a flintlock has to burn before the main charge fires; and the flint strike has to put the sparks into the primed pan. A percussion is not so different from a modern cartridge. The hammer hits and explodes the cap which injects the flame directly into the main charge.

What amazes me is that they they both sound instantaneous to my ears.

 

[George]

In the 1977 second edition of the Black Powder Gun Digest a study was done trying to answer that question. They used a camera filming at 7000 frames per second, and measured the time interval starting when the hammer began to move and ending with the appearance of smoke at the muzzle. Their equipment wasn't capable of seeing the ball. They used a bench gun with a professionally tuned Tower lock for the flint, and an underhammer rifle with a straight shot into the powder as the test guns.

Their results showed a speed of .055 second for the flint, .022 second for the percussion.

Spence

 

[Larry Akers]

My question here is regarding the relative difference in time it takes between priming ignition, and projectile exit

Related to this topic, I'm curious to know what differences are manifest when using a regular flint breech, a Nock breech and a Manton breech.

 

[Billnpatti]

I don't know if a study has been done to resolve these questions. If you can't find anything and no one knows of any such study that has been done, you ought to get with Larry Pletcher and see if you can't get him to do such a study with his high speed camera equipment. He just may find such a study to peak his interest.

 

[crockett]

I was told the heat of the priming charge was what ignited the main charge- not any burning though. If that changes the situation on the pressure in the bore- don't know. A prb might also get moving much easier than a conical.
My take on accuracy is the slower lock time AND for many shooters the flash in the pan causing follow though issues.

 

[hanshi]

I'm rather sure it's the burn of the prime and not the heat that sets off the main charge. And I'm completely satisfied when the gun goes "BANG" and without a lag. :grin:

 

[Col. Batguano]

I agree, and the emperical data from the 1977 issue is a very good reference point. Just using my own ears as a guide, there is a fair amount of banging and clacking that goes on in a flint gun before the bang. With percussion, it seems to all happen at once--only one bang (if I've loaded it right).

I'm also guessing that with flint, the charge is burning from one end to the other. With percussion, given the volume of gas coming out of the cap, my guess is that the charge is ignited throughout the charge, and burs through much more quickly. I don't have any data to back it up though. Just an intuitive reference.

0.03 seconds is a long time difference. A muzzle wobbling across the bull at 4" every .1 seconds (50 yards) will move 1 3/8" in that time, and you can double that for the wobble going back the other way. Put another way, a shooter that shoots consistent 9's and above in a percussion gun is doing equally well to poke out 7's with a flinter.

 

[azmntman]

I realize Pletch did a quite a number of very good HS videos some years ago showing the difference in lock speed with various powders, locks, etc. As I recall, the fasted=st flint locks set off the pans around .045 seconds, and the fastest percussion locks were around .030 seconds.

My question here is regarding the relative difference in time it takes between priming ignition, and projectile exit (lets assume equal muzzle velocities and equal barrel lengths, as, we also know that a flint lock load needs to be about 5% greater than a percussion load to achieve the same MV.

Intuitively speaking, it would seem that the pan flash has to burn up and reach a sufficient strength before the fire can work it's way through the touch hole to set off the main charge. The main charge burns, builds pressure, and shoots gas out the touch hole until the gas can't escape any more, and then the ball is started on its' way.

With a percussion gun once the cap goes off most all of that flame is directed through the nipple right in to the heart of the main charge. Just like with a flint gun, there's pressure push back against the cap, cock and nipple, but that is much more tightly sealed in a percussion gun than the open hole in a flinter, so the ball seems like it ought to start on its' way faster too.. Intuitively, the charge consumption process seems like that too ought to be faster in a percussion gun than a flint gun. Have tests been done to measure total elapsed time from sear trip to ball exit between the 2 systems (all other variables adjusted to be constant)?

I'd be curious as to the findings if they do indeed exist. That is, my hunch is that lock speed is only PART of the reason a flinter is inherently less accurate than a percussion gun.

I have not seen that myself. I have but one flinter and have neglected to shoot it much lately but it IS AS ACCURATE AS ANY OF MY CAP GUNS. Last outing I was shooting against my son at 90 yds. We had set up clay birds and I did not fail to hit one in ten shots. On paper at 90 yds it was 2-3 inches IIRC. Once your used to the flinter and stop worrying about the flash I believe the guns can be as accurate as any cap gun. Thats just me though, and I have been reminded by the better half (just recently) that "I am just a man and know NOTHING" :idunno:

 

[Larry Pletcher]

Col Bat said, " Have tests been done to measure total elapsed time from sear trip to ball exit between the 2 systems (all other variables adjusted to be constant)?

I'd be curious as to the findings if they do indeed exist. That is, my hunch is that lock speed is only PART of the reason a flinter is inherently less accurate than a percussion gun. " (end quote)

Yes, we did that. We used a pistol stock from Jim Chambers that has a lock mortice for a small siler. We used a barrel stub 9-10 inches long and timed from sear trip to photo cell at the muzzle. We timed a s. Siler percussion, s Siler flint, and a mule ear made by a friend to fit the same lock mortice.

In all these time started when the sear was touched by the solenoid plunger and stopped with the photo cell at the muzzle.

I don't have the numbers in front of me, but the percussion locks were in the .020-.030 range. The flint gun was in the .070-.080 range. A sizable chunk of the flint time was the E.T from pan ignition to barrel ignition - probably in around .035.

It take a good flintlock to ignite under .0400 and .035 is about tops for pan to barrel ignition. Just for kicks, the all time best time I've ever gotten from a flint pan ignition was an original Joseph Manton that averaged .0299.

These numbers are from multiple experiments and as best as I can remember.

Regards,
Pletch

 

[don hepler]

It seems to me, that there are a lot of variables. There is spring weight, friction, hammer mass, and on and on. :surrender:

I think we must concede that a cap lock, on average, is a fraction of a second faster than the average flintlock. That alone, is not going to stop me from shooting a flintlock. Mastering a flintlock, and getting the best performance, from "my" rifle is my goal. I'm after the "flintlock experience" and my big Siler lock on average, is probably better than most flintlocks. No need to compare apples to oranges.

My flintlock is faster than your flintlock. :rotf:

 

[Col. Batguano]

Fascinating data. Thank you so much for the information.

Of course, if a gun is locked in a fixed position (like in a vice) and there is no wobble going on, the lock / ignition time is moot. A slow cannon fuse will give you pretty much the same results as instantaneous electronic ignition in that case. The more unstable the position (like standing position for instance) the more difference in group size the difference in lock time makes.

 

[Larry Pletcher]

. . . . . snipped. . . .It seems to me, that there are a lot of variables. There is spring weight, friction, hammer mass, and on and on. . . . .:

No question that there are tons of variables. It's the biggest headache of an experimenter. In each test I do I try to eliminate variables to the best of my ability. I do feel that my biggest testing headaches are squeaky clean vents, flint edges, and priming techniques.

Regards,
Pletch