Fly fly away

[Pete G.]

Having taken all of the precautions of disassembling the lock, wrapping the detent in a piece of masking tape and putting in its own little plastic box, I now cannot find the box after moving the shop. I am using a large Siler in a single trigger application, so theoretically the detent is not necessary anyway, but I am wondering if a lock designed for one will have any problems with the sear catching on the edge of the half cock notch.

Does anyone of you have experience with intentionally leaving out this little piece in a single trigger application?

[kaintuck]

Some people say to remove it when a single trigger is used...............
marc n tomtom

[flinchrocket]

I would not use it without the fly. There's a chance of getting the nose of the sear broken off and it would
not fit in the full cock notch properly, could cause an accidental discharge.

[smallpatch]

Get a new one, unless you plan on keeping a 10lb trigger pull.

[Lucky R A]

    In your single trigger application there is no need for the fly to be in place.  Single triggers operate by you mechanically putting pressure upward by the leverage provided by the trigger.  As the sear disengages from the tumbler notch the finger continues with the pressure against the trigger preventing the sear from dropping into the half cock notch.  With a double set trigger you mechanically disengage the  spring assisted rear trigger bar to violently snap upward knocking the sear free of the full cock notch.  The sear spring of the lock can then push the sear back into the half cock notch; thus, the need for a fly to prevent this from happening. 
      In a single trigger application there is no more likelihood of an accidental discharge with or without the fly.
      The fly has absolutely nothing to do with the trigger pull; this is determined by the leverage and the location of the fulcrum (trigger pin)   

[P.W.Berkuta]

I had a woman shooter (a very good competitive shooter) bring me a Dixie Cub that was tuned by a smith that had a very light trigger pull. She was experiencing hammer "hang-up" in the half cock position some of the time. She had such a light application of pressure on the trigger that the hammer fall would some times get caught in the half cock notch. I ended up annealing the tumbler and cutting in a fly to prevent the hammer from catching in the half cock notch. As others have said in your application you very well may not need the fly but if the lock has the provision for one why not use it ?

[Long Ears]

I have added a fly on 3 or 4 percussion locks that had a light trigger pull. They kept breaking the nose off of the sear. I personally wouldn't purchase a lock without a fly. It just eliminates the possibility. Bob

[smallpatch]

Lucky,  my reference to trigger pull is based on keeping that sear pulled back far enough to keep from re engaging in the ½ cock notch.  A very light pull will often allow the sear nose to just slide along the tumbler, and re engage.
If the fly is in place, you can make it as light as you want without fear.

[smylee grouch]

The cost of a new fly is so slight I would buy one and another one for a spare.

[Bob Roller]

I have added a fly on 3 or 4 percussion locks that had a light trigger pull. They kept breaking the nose off of the sear. I personally wouldn't purchase a lock without a fly. It just eliminates the possibility. Bob

I have noticed that fine English double caplock rifles have locks,frequently
made by J.Brazier that have a fly in both locks.An identical smooth bore
will have NO fly in either lock. Military guns as far as I know have no fly in the
lock. Some Swiss muzzle loaders have no half cock or "first position"so none
is needed.Of this group, NONE have set triggers except the Swiss rifle.
A lot of people,especially newbies that already know it "all"think a fly is a
gadget that speeds up the lock.The reason I say this is that years ago,I made some locks
for target shooters with no first position and was told by one of these self styled experts
that it HAD to have a fly. I told him the correct function of this little device was an intercepting
cam that rode the sear over a half cock position that these locks didn'r have. He still didn't
"get it".

Bob Roller

[Pete G.]

The cost of a new fly is so slight I would buy one and another one for a spare.

Seems like every time I buy a small part I always try to add enough to the order to make the shipping worthwhile. Because of this I now have almost all of the books about gun building that TOW offers, along with some continental money and a few tomahawks that I have no use for whatsoever. I once went to Track to order a dozen flints and it cost me $1800 . That came from "AW, just throw that gun in on the order also".

Incidentally, I did have a lock where I used a high pressure grease on the tumbler and ended up chipping the sear because it effectively disabled the fly, even though used with a single trigger. That experience was why I asked the question to begin with. I think that I will go with the consensus and order the replacement part, even though I know it is going to cost me.

[Mike_StL]

The surest way to find your box with the fly is order a replacement.  It is almost a certainty that the day your new fly arrives the box will turn up. 

My vote is to get the fly and use it in the lock.  Stay away from the heavy grease.

[jerrywh]

I agree with Mike_StL only get three of them.  You are going t oloose some more. Someplace in my shop there are at least 5 flies hiding.

[Acer Saccharum]

Get some of that sticky fly paper. I've never seen a fly escape from that.

In theory, a single trigger doesn't need a fly. If your notch geometry causes the sear to pop out of engagement, the sear WILL hit the half cock notch. See if your lock holds full cock with the sear spring out of the lock. (use a wooden stop block to keep the hammer from falling on something you don't want it to, like your fingers)


A note on safety: the sear should hold full cock even when there is NO sear spring. The geometry of the notch and sear must not cause the sear to push out of its notch on its own. Why? If the sear spring should fail, you do NOT want the gun to off by itself.

[flinchrocket]

It seems to me that if the nose of sear doesn't push the fly down in position to keep it out of the half
cock notch, even with heavy grease, the fly is to short. Comments?

[Acer Saccharum]

The sear nose is supposed to drag the fly backwards until it the sear can't travel any farther. When the sear nose rides up and over the fly, it forces it to pop forward in its pocket while the sear drops into the full cock notch.

When the sear is forced out of its full cock notch, it contacts the fly's ramped surface which causes the sear nose to rise up and over the half cock notch.

[Pete G.]

It seems to me that if the nose of sear doesn't push the fly down in position to keep it out of the half
cock notch, even with heavy grease, the fly is to short. Comments?

Possibly so, but I replaced the sear and used Break Free for the lube and have not had the problem since. Perhaps there was an issue with the fit of the original sear.

[flinchrocket]

I think in a cold weather situation, the fly may not pop into position. I would want mine to push the fly down where it belongs if it didn't snap in by itself.

[kaintuck]

I saw a horse fly,
I saw a barn dance....
But I heave seen everything when I seed a elephant fly......

Marc n tomtom

[smylee grouch]

I never seen some of that stuff but I have seen a flintlock rock!