small percussion lock by Bob Roller

[D. Taylor Sapergia]

Bob asked me to post these pictures which he hopes will benefit some of the folks on this site who are interested in such things.  Bob can comment further if he chooses, to describe the idiosyncrasies of the lock and its function.  If you left click on the image it will enlarge...click it again and you will get a full screen view.

[Scota4570]

Beautiful

[flinchrocket]

I only have a question. I assume the pin that goes through the sear is shouldered so it can’t fall out. Is that correct? Thanks

[Bob Roller]

I only have a question. I assume the pin that goes through the sear is shouldered so it can’t fall out. Is that correct? Thanks

I wanted ScotA4570 to see the proper lock for an English mid 19th century gun.This one is a very close copy of one taken from a Whitworth boy's rifle owned in 1998 by Lynton McKenzie.I had the lock and made guages from it and still have them.I also made about 40 of an identical version and only 8 of these smaller ones.No castings except the hammer which is from L&R and fine quality.Like all my locks and triggers they were bench crafted and having a machine shop helps a LOT.The 40 were for full size target rifles.
In answer to the question about the sear pivot pin,it is a .09375 dril tod pin thru a .0938 hole. that's .0005 clearence or 5/10,000ths of an inch.The pressure of the sear spring does what holding is needed. and on the bigger one it;s a .1094 pin and a .110 hole.I am a bit nutty on precise fits that still allow movement as needed.
Thank again to Taylor for his help.
Bob Roller

[Scota4570]

To make a bridle like that do you use pillars-bushings and silver solder them in the flat part?  Or, scratch it out of solid stock? 

[Bob Roller]

No scratching of any kind.This is a precisely laid out job that starts with a piece of low carbon flat ground of a size needed and 3/8"thick. Is drilled and counter bored for the screws and witness marked for the sear in and the small bearing on the tumbler which is .140 into a finished hole of .1405.It is then mounted on a mandrel thru one of the screw holes and placed in a 3 jaw chuck on a small lathe and then a hollow mill is used to establish a 3/16" witness mark x 4 in this case. It is then placed on precision paralells in the vise of my vertical mill and the deppth of the cut is estblished at a depth of .231/ .233 and then avoiding the 4 witness marks made by the hollow mill,using a 5 or 7 flute high spiral carbide end mill I remove all uneeded material.A 1/8"5 flute carbide end mill is used to go between the witness marks for the two upper bridle screws.After that it is moved back to the lathe and again the hollow mill is use to finish the posts.After that the hardened filing guides of .203 diameter are inserted thru the screw holes like a nut and bolt and the fancy detailing is done until it looks like an old British original,Most of this is filing after roughing it in with the milling machine and a 3/16" carbide end mill.These were and are labor intensive and practice is involved over a long period of years so don't be disapointed iif the first try fails.
   The tumbler,springs and link and fly and tumbler all require the csame attention to detail.These locks when new in the mid 19th century as well as today are not aimed at a distressed market and are luxury items like the guns they appear on.
Bob Roller