Thanks Bob, I will definitely triple check it all.  I've had the thing apart a few times and the sear seems to move freely.  I've checked everything that I've read of here in the past but it never hurts to check again. 

One of the reasons I started to suspect the fly is that when I put the entire lower tang/trigger assembly into a different rifle, it all works perfectly. 

Chris.

. . . while building a 44 1/2 from scratch

Except for Greg, I can't imaging anyone else doing such a thing, especially and most likely just for the fun and challenge of it.  That being said, I'm also sure the end result was not just commendable but also more than likely better than the originals here and there.

Bill Lawrence

I should add that I just reassembled the rifle without the fly.  Now the sear holds in the full cock notch regardless of how slowly I cock it.  I guess now I have to understand more about the fly and how it should operate .

Chris.

OK; we progress!

So what I did was to round off the trailing edge of the fly projection which protrudes into the fullcock notch when it is down, the better (I hoped) to allow the trigger sear to rub or push the projection out of the way and seat itself into the fullcock notch.  An unaltered CPA fly is at the top of the picture, the slightly tweaked one I'm messing with on the bottom.

You can see the rounded trailing edge, I hope; I didn't want to take off too much.

I'll be interested to hear how yours works now.  On mine, when the fly is pushed forward all the way like yours, nothing covers up the full cock notch at all.   

I'm learning a lot on this thread.  I think we have similar problems but I think mine might be because the angle on the fly doesn't allow the sear to push it correctly to uncover the full cock notch. 

Is your fly polished smooth?  Mine has some surface roughness on it.  Mine is also fairly sloppy with regard to the fit on the hammer screw.

I might pop apart one of my other rifles to compare.

Chris.

The flies as they come from CPA are pretty smooth on the sides, but there are some slight nicks or ridges on the edges.  I burnished these off with a dull file (the edges can be smoothed somewhat with a file, but not easily; they're almost as hard as the file is).  I can remove burrs from grinding from the sides with the same dull file.  But I've been using a little hand crank grindstone to remove any significant amount of material.

When an unmodified fly is pushed all the way up, there is nothing projecting into the fullcock notch, and it completely but just bridges the halfcock notch. But it will project into the fullcock notch a little bit, as the picture shows, when it is all the way down.  At this point, there is plenty of room in the halfcock notch for the trigger sear, but not enough to allow the fly to rock up completely enough to keep it from projecting into the fullcock notch, as the photo shows.  I don't see any evidence that the slots in the hammers I have have been altered or widened or whatever.

To answer another question I've neglected, the set triggers can be set on the 47 and the hammer still will not cock.  I am snugging the forward trigger plate spring just enough to hold; not tight.  Must have missed that advice; never heard there was a problem tyat way before.

I would imagine that an extremely heavy trigger spring would allow the trigger sear to push or rub the fly out of the way, no matter what the configuration, but I can't but believe that this dodge wouldn't result in a separate set of problems that I'd rather not deal with, especially with a set trigger mechanism.  Trading Stevens fly movement problems for a Remington Military Rolling Block trigger pull would be trading the classic headache for the upset stomach. 

The 5 flies I ordered from CPA were the same shape as the one on my lone original 44-1/2 that still has one, and the pictures in deHass' books.  Maybe a slight oversize (caused by blanking?) top and bottom, but the same shape overall.  One fit the original hammer pin well; another had maybe a slight burr that required twisting it on the hammer pin.  A little polishing should make it spin fine.  Making the blanks  few thou large and the holes a tiny bit undersized to fit worn pins would be a prudent move by CPA, I should think.

I replaced the hammer pin on the 47 to better fit the hole in the hammer. I had to drill the hole out in the fly for that one slightly to make it fit.

I think I'll declare provisional victory on the first one and tackle the other tomorrow or the next day.  I need to reload some more ammo anyway, for a range test.

So, you will need to study what needs to be done.  In your picture of the hammer, I can't tell if the fly is against the stop on the full notch side, it is very close to working in the position shown.  If it is, would filing a little off the stop (#1 in fly photo) let it come around a bit further and clear the full notch, but leaving the hump in front of the full notch?  Or, would filing a little off the stop (#1) plus slightly modifying the length of the fly at #3 fix the issue, but not so much that it will not work for the half cock notch.

Not really looking for an answer just want you to keep an open mind as to what it will take to fix the issue.

I would assume the CPA flys are over sized for fitting, at least I hope they are.

Sorry for this being really wordy, but don't know how else to ask the questions.
Bob

FYI, when I built the 44 1/2 the fly would not work because I did not pay attention to the stops and the proper depth when I cut them. The second hammer work with the fly without any issues.