Looking for a good picture of a fly

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sherpadoug

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Two entomologists walk into a bar... whoops wrong forum

My flintlock is having trouble with the sear catching in the half-cock notch on firing. I am considering making a new bridle for it, or some other major surgery. It is a Brown Bess style fusil and does not have a fly. I would consider adding one except I don't know how they work or even what one looks like. Where can I get a good picture of how a fly works. There are many pictures of locks but none I have found clearly shows the fly.
 
I don't know how to post a picture or I'd show you how I did one for my Charleville. One that would work well in your fusil, which I assume has a musket lock, though maybe a little smaller, is a piece of hardened steel about 3/8" long by about 1/4" wide and about 1/16" thick. It is rounded on both ends with flattened sides. You drill a hole (centered) near one end. This is for a pin about 1/16" diameter and about 3/16" long. You will need to mill a recess as deep as the fly is thick in your tumbler. I don't have any measurements handy, but the recess needs to be large enough to allow the fly to move enough to swing out of the way of the sear when setting it on half cock. The upper end of the recess needs to be near the spindle of the tumbler and a hole for the pin drilled near that end. Now, the figures I gave above are only approximate, as I don't have my lock in front of me and I believe my lock is bigger than yours anyway. Another type of fly such as come with Siler lock kits are cast with the fly and pin as one piece.

When you cock the piece to fire, the fly drags on the nose of the tumbler and when it clears it, it swings down in front of the half cock notch. When the trigger is squeezed, the tumbler is released and as it rotates the fly rotates with it and blocks the nose of the sear from catching in the notch. That's one of the reasons it is rounded on the ends. It allows the sear to slide by it. Only a small portion of the outer edge of the sear contacts the fly. The fly needs to be hardened somewhat so that the sear won't wear a notch in it.

I'm sure one of the moderators can post some good pictures that will detail what I'm talking about. I need to learn how to do that. Also, you need to get with a shooter who has a rifle with a fly, or better yet, a builder, and they can help you figure how big a recess to mill and the proper length for the fly. My Charleville would hang up if I squeezed the trigger and I had to jerk it to clear the notch which didn't help accuracy. I looked at how it was done on my rifle lock, allowed for a much bigger lock, crossed my fingers and started milling. It made a huge improvement. I hope this poor description helps a little.

How 'bout one of you Moderators post this feller a picture? It would have to be clearer than my description.
:: :results: :m2c:
 
I quick drew a rough picture for you.
fly.jpg

This is supposed to be a tumbler, with axle for bridle and half and full-cock notches. The fly is the black gizzie and rotates on an axle or pin that is 90 degrees to the surface of the tumbler and drilled straight in.
 
Thanks Rich, That's made a lot like the one on my flint rifle. The one on my Whitworth is oval shaped with flattened sides. It's the one I used for a pattern for my Charleville. They're both a heck of a lot bigger than my Siler lock fly. I'd recommend to anyone who has a problem with sears catching on the HC notch to make one or have one made. I can squeeze off on that old musket now instead of jerking the trigger and holding it and it has greatly improved accuracy. ::
 
:results:The only times I have had problem as you describe was when I had the trigger let off set too light. If I made it just a bit more firm, there was enough trigger follow through for sear to clear the half cock notch.
 
PS: Unless you have badly adjusted set triggers, catching half cock on the way down is usually a sign of overtight lock bolts bending the plate.
 
The problem with my Charleville was the fact that the half cock notch was so big and deep you could bury a Jeep in it. (or LandRover for our friends in GB.) I don't have any problem with my rifle-musket which also has a pretty big tumbler. It may be that my C-ville tumbler's shape is a little out of whack and the notch actually sticks out a little too much. I'd have to take it out and give it a good look. Anyhoo, the fly fixed the problem. I only just barely snug up the lock nails on all my guns. Overtightening will definitely bind things up.
::
 
Thanks to all that replied. KanawhaRanger's essay and Squire Robin's photos tell me whole lot. I think I have enough info to add a fly this weekend.

The two screws holding the lock to the stock were stripped by a previous owner, and I made new screws. But the lock catches half cock even when held by a vise at one point. Maybe the plate has a permanent bend, but I don't see it.

I suspect the root of the problem is that the bridle is only held by two screws, one of which is the sear screw which can't be tight or the sear binds. As a result the bridle wobbles as the trigger is pulled. I am going to make a new bridle which uses the sear spring screw as well for three points of support.
:thumbsup:
 
That's odd that your bridle only has two screws. All that I have ever seen have three. Guess I just ain't seen it all. Anyway, redesigning your bridle with three is a good idea. That should take care of the wobble. And adding a fly wouldn't be a bad idea either, especially if you have set triggers. Good luck and let us know how it turns out.
:thumbsup:
 
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