Zonie said:
I assume when you say,
"However, I have run into many locks where adding that angle still did not give quite enough clearance for the sear nose to pass by the half cock notch. Then you have to cut the half cock notch shorter, but still maintain the angle as you shorten it.", you are talking about reducing the wall thickness that forms the half cock notch?
(The wall being the metal between the open notch and the outside of the tumbler in that area.)
You don't really mean that the half cock notch would be shorter do you?
Hi Zonie,
Yes, I could have described that better, though we are talking about the same thing.
OK, allow me to try describing it differently and this time with some links that show drawings or pictures of tumblers.
Here is a link where in Figure 3 of a Tumbler for a 1861-64 Springfield Rifle Musket that shows reducing the “wall area” as you describe it so the nose of the sear does not hit the half cock notch as the tumbler rotates. (There is a difference between this tumbler in the full and half cock notches because it was designed for a percussion musket, rather than a flint lock, but I will get into that later.) The distance or amount of metal from the pivot in the center of the tumbler to the outer “wall area” of the half cock is shortened to allow the sear nose to pass by without hitting the half cock notch, but please notice the “hook” part of the half cock notch is also shortened by taking metal off the “wall area” of the half cock notch. I hope this explains what I was attempting to describe in my post above.
http://www.nwtskirmisher.com/useful-locks.shtml
Here is another picture of the same tumbler. Please note the distance is pretty large/long from the Full Cock Notch to further around the tumbler to the Half Cock notch. These Tumblers were specifically designed with more distance between the full cock notch and the half cock notch to allow more time for the sear nose to be pulled further away from the half cock notch as the tumbler rotated. This really reduced the amount of damage of the sear nose hitting the half cock notch as it the tumbler rotated and pretty much kept it from happening as long as the parts were in good/serviceable condition. However, you DON’T normally see this much distance between the full and half cock notches of Tumblers made for Flint Locks.
http://www.ssfirearms.com/proddetail.asp?prod=58S169&cat=88
Though this next link only shows a rather crude casting of a Brown Bess Tumbler, it is easy to see the distance from the full cock notch to the half cock notch is much closer than on the Percussion Tumbler shown in the upper two links.
https://www.peterdyson.co.uk/acatalog/T224.JPG
Here is a picture of a modern machine turned Tumbler for a 1746 Willets - Brown Bess flint lock. The distance from the full cock to the half cock notches are a little further away than on an original Brown Bess Tumbler and this time the full cock notch is a little further “higher up” the tumbler, yet the distance between the notches is not as great as on the Percussion Tumbler. By having the full cock notch higher up the tumbler, this also gives a little more time for the sear nose to be pulled away before it would hit the half cock notch. However, this also causes the Cock/Hammer to have to be pulled further back and thus the “throw” of the Cock/Hammer is longer and lock time is a bit slower. Pedersoli Brown Bess Tumblers have even a little more distance between the notches than this tumbler and I believe it also was done to allow more time for the sear nose to be pulled further away so as not to hit the half cock notch. (Dave Person recut the Full Cock notch so it would be closer to the Half Cock Notch on the Pedersoli Brown Bess in his superb tutorial on making the Pedersoli more historically accurate. Dave did that to reduce the “length of throw” from the half cock to full cock and thus speed up the lock time.)
https://www.trackofthewolf.com/Categories/PartDetail.aspx/727/1/LOCK-BESS-46-TU
This link shows a Tumbler for an original M1816 Flintlock Musket and the notches are also much closer than on the Percussion Tumbler shown above, though unfortunately with the angle of the picture, it is not easy to see it.
http://www.ssfirearms.com/proddetail.asp?prod=W17089
Though I realize most of the gun builders on the forum realize the following, I think it is important to talk about the function of the Half Cock notch for some of our forum members. So for those who already realize this, please bear with me.
The main purpose of the Half Cock Notch is to hold the Cock/Hammer far enough away from the frizzen on a Flint Lock and far enough away from the Nipple on Percussion Locks so the lock can be “primed” and in the case of the Flintlock, so the Frizzen can clear the front edge of the flint and close properly over the priming pan. (The secondary purpose of the Half Cock Notch is as a safety feature in case the sear nose slips off the Full Cock Notch before one deliberately intends to fire the gun. In that case when one is not pulling on the trigger, the Sear Nose will enter the Half Cock Notch and therefore [hopefully] keep the gun from firing unintentionally.) Now we have to keep the main function of the half cock notch in mind when/if we have to adjust the half cock notch to keep the sear nose from striking it.
For example, one time I tried to fix a broken Half Cock Notch by filing the notch deeper or further into and down the Tumbler. The newly filed notch corrected the “safety feature” of being able to hold the Cock/Hammer on Half Cock. However, much to my embarrassment/chagrin the Cock/Hammer now went too far forward and there was not enough clearance between the flint and the frizzen, to close the frizzen for priming. One has a little more “wiggle room” to do that on Percussion Locks, as long as the Hammer is still far enough off the nipple to place a cap on the nipple at Half Cock. So I have been able to save some Percussion Tumblers that way.
However, the better way to do that (if possible) is NOT file cut the notch further down the Tumbler, but rather file the notch sort of upwards to get the sear nose to stop in the new file notch, but not go further toward the front of the Tumbler. That way the Cock/Hammer does not go forward or only a very small distance and you can still prime the Lock. This removes metal near the Full Cock notch, but normally not enough to cause the Full Cock notch to be too weak. I used this method to “save” an original Tumbler on an Early Percussion Jaeger Lock at the IMLC World Championships in 1996 and again on an Original Nicolas Botet Flintlock Dueling/Target Pistol at the 1998 World Championships.
One final thing for this post and it is about a modification I do to the Sear Nose Face that helps keep the Sear Nose from catching on the Half Cock. This is to SLIGHTLY stone an angle going backward on the top of the Sear Nose Face. Now you can’t do this on every Sear Nose Face, because some of the Sear Nose on Civilian Locks are just too short from top to bottom of the Sear Nose Face, though on those I just “break the sharp edge off the top of the Sear Face” with a stone. On larger Civilian Locks and Military Locks you can do this angle. In the following link in Figure 4, it shows where to stone this angle at the top of the Sear Nose Face in dark black. However, I DO NOT round or angle the bottom of the full cock notch as is shown in that illustration. If one does that, you add a lot of “roll” to the trigger break that most folks don’t like. I DO just break the sharp edge off the bottom of the full cock notch with a Hard Arkansas stone, though.
Now I will DO/stone this angle on the bottom of the Half Cock Notch similar to how it is shown in this figure. Unless I’m mistaken, I believe this is what Zonie meant when he said to slightly angle the bottom of the half cock notch as well? These slight angles on the top of the Sear Face and the bottom of the half cock notch also allow just a bit more time/room for the half cock notch to pass the sear face or if the sear face does occasionally hit it, it allows the Sear Face to sort of Cam Over the bottom of the Half Cock Notch.
http://www.nwtskirmisher.com/useful-locks.shtml
I hope this clears things up a bit.
Gus
