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Possible L&R Durs Egg design flaw

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The cock went flying and the retaining screw failed on an almost new Durs Egg. This is not a new problem to me as I have another on an older gun. The square post on a flintlock tumbler should be flush with the hammer face, and is on my other locks. The post on the L&R durs egg barely engages half of the hammer, see photos. There was an .080" void from cock face to post on my latest lock. I worked down the back of the hammer to reduce this to .025" and fitted a copper filler to take up the rest. Just seems like poor engineering and I'm wondering WHY IT IS LIKE THAT. Included are some photos including a comparison of what the tumbler post should look like, my remedy, and three durs egg tumblers, all short. Picture of the beautiful new Bedford rifle with said lock. .40 cal 15/16x44" Douglas barrel. Comments welcome.
 

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Hi,
There is no logical "why", it is just lousy assembly. The flint cock should be fitted to the tumbler such that the face of the tumbler shaft is just shy of the surface of the cock and the cock rests against the shoulder on the tumbler. That makes sure the tumble screw tightens it down properly. I deal with this all the time on poorly assembled locks, mostly L&R and Davis locks. The square tumbler shaft can be stoned until the cock fits down against the shoulder. In your case, I would send the lock back to L&R and have them fix it. They used to sell a little "press" that pushes cocks and hammers down on the tumbler post. I have one and it works very well. The new CNC machined locks by Chris Laubach and Jim Kibler will eventually eliminate this kind of stuff.

dave
 
I ran into the same thing on a L&R RPL lock for a TC Renegade, the cock was so far off the lock plate that the cock stop barely nicked the corner of the lock plate when the lock was fired. I sent it back to L&R, they ground the tumbler shaft back to the right place BUT..... they created a huge burr in the grinding process and forced the tumbler shaft back through the lock plate burr and all, undoubtedly they used their "special" press. I tried to cock the lock when I got it back and it took both hands just to move the cock back just a little. I disassembled the lock, the problem was easy to spot. I carefully filed off the burr, polished the tumbler shaft and tumbler hole in the lock plate and everything worked like it should, there didn't appear to be an slop in the tumbler shaft.

The first RPL lock I got had a huge casting void in the nose of the lockplate, I sent it back and got the one with the tumbler shaft ground incorrectly, sent it back and got it back put together with the burr on the tumbler shaft. My $180 lock cost me $215 with all the shipping back to straighten things up.

I don't understand how people who make locks for a living can be so sloppy in their quality control, a six year old could have seen the problems with these locks before they were shipped.
 
Thanks for the replies and agree about fitting at the factory. However if the cock is .190" thick at the hole and the squared portion of the tumbler is only .110" in length, I call foul. It should be at least as long as the hammer is thick so it can be properly fitted. I did work it down as Dave said, but it is still not optimal IMO.
 
Hi Joe,
As I mentioned, it is really an assembly problem. The Durs Egg lock is a pretty good design but cast parts vary so much that good assembly is essential and that is where the cost is. On some Durs Egg and L&R Bailes locks, I have had to anneal the tumbler and file down the shoulder to extend the square post. However, I don't want the post to be perfectly flush with the flint cock. I want it to end a couple of thousands of an inch below the cock so the tumbler screw can tighten against the flint cock not the end of the post. I do this work rather than send it back because I do better job. An L&R or Davis lock takes me at least 10-16 solid hours of work to bring them to my standard of quality and performance and that does not include polishing the outside. You want to see a design problem, look at this mess. It is a "Tulle" lock sold by Track of the Wolf.
9jmASBZ.jpg

Look how far out the cock is from the plate. The reason is the thick lock bolster on the plate is so short that the shoulder on the cock barely reaches it when it is at rest. Most of the shoulder rests on the thin edge of the plate behind the bolster. The shoulder is deeper then the thickness of the lock plate so if the cock was closer to the plate as it should be, you could not inlet the lock properly. When you cut away enough wood to allow the cock to clear the stock, your cut is deeper then the edge of the plate. Track's solution was to extend the tumbler post so only a corner of the shoulder hits the lock plate. Fortunately, I was able to fix this mess and with other changes, produce a good and historically correct lock.
a0WQ1wE.jpg


dave
 
Nice work.
The lock plate/cock clearance was acceptable from the factory, around .025". It is now about the thickness of a dollar bill. But, however the parts are manufactured nowadays, very little machining is need to make them work. So why did I have to file about .030" off the back of the cock and still end up with a .020 void between the face of the cock and the tumbler pivot? My guess is the L&R durs egg percussion lock has a thinner hammer. The tumblers being the same part #, they saved money using the stubby tumbler shaft for both locks.

PS, I did obviously need to cut away some wood from the lock moulding for the modified hammer. Fortunately, the lock plate is thick enough in that area.
 

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