Fine tuning a trigger for accuracy?

[Captchee]

melsdad
 This is because of a potential  lawsuit  that was files a couple years back against  Lyman. They used to have very good easily tuned triggers . However  you could tune the double set triggers to where they only had about 1lb pull .
 The person who filed the lawsuit did this which made the gun unsafe  and it went off before he was ready to fire . From what I was told this resulted in a hole in the covered  section of the range he was at and  his removal from the range.
 Lyman then followed this by putting  a shorter adjustment screw in their double sets and a greater angle on the full cock notch   .

 This made it so the only way someone could get a better trigger pull was to modify the  tumbler or change out the adjustment screw .

 You problem stems from this .
 Whats happening is as you pull the trigger the sear must cock the lock back just alittle before the sear will fall from the full cock .
 You can fix this but it will require filing the full cock notch . If you chose to do this , DO NOT  file the notch past 90 deg .
 You should not attamt to shorten the depth of the notch as the lyman tumbler design  is  so that the full cock notch is just outside the  plain of the half cock .
 By shortening the depth of the full cock you will bring it into the plain of the half cock . The fly will let the sear slide for a time but  eventually you will find it hanging   on the half cock . When you  then take the lock off you will find that its really hanging on the fly . This is cause by a burr that is formed by the sear contacting the fly  at the wrong angle for the design

[melsdad]

I totally understand what you are saying about the angle Captchee. If the angle were taken past 90°, the sear would simply want to fall off of the tumbler, and be totally unsafe. I am sure the design of the lock assembly as it is now, is for protection of Lymans own butt.

[Sir Michael]

It is my understanding of the sear/tumbler interface is that the surface of the tumbler full cock notch should be on the plane of a straight line drawn from the pivot point of the tumbler through the outer perimeter of the tumbler and that the face of the sear that interfaces with it should be the same angle so that they are flush.  If this makes sense.  

[melsdad]

That makes sense to me Sir Michael, I will look at this more closely.

One problem I have is (refer to picture of lock) the 2 screws that are next to each other, holding the small plate that covers the tumbler. The threads are about ruined on the screws, and the threads in the lock. I fear that if I take this apart one more time I will be forced to make new screws, and I will need to put helicoils in the threads in the lock plate. I have only removed the screws twice and I noticed the first time I removed them, the threads looked like were tore up from when the lock was assembled. So far this is the only downfall I have come across with this gun.

[Sir Michael]

:?  

[Captchee]

no need to  replace the lock because of the screws . simply replace them with a fraction higher screw . If the thread in the lock plate itself are striping then  the plate  can simply be re-taped .    If your threads are stripping in the lock plate , my bet is that the plate it self is not hardened which is not un common  to see in production guns . those two screws shouldnt create a proble in doing this  as they are not pivots for anything , just  screws that hold the tumbler bridle  in place .


  If you have no experience in this , simply take it to a gun smith and have them do it .
  They will either tap to a large screw or weld the hole closed , clean things up  , re -drill and tap the holes.
  folks to many times  when disassembling locks think everything need torqued down  . I see this from everything from lock screws themselves  to  the lock plate screws. .
Folks just apply alittle lock tight and then snug things down , no need to reef the pudding out of the screw to seat it .

[Dragoon]

Does your weapon have the set trigger assembly? If so, there is a screw between the two triggers that adjusts the trigger pull. I discovered this last night looking up parts for my Lyman Plains Rifle. I plan on doing some cleaning and polishing first and then testing out the pull and adjusting it. Mine could be lighter than it is, but not a lot once I have pulled the "set" trigger.

Go to http://www.lymanproducts.com/lymanproducts/index.htm and look up your gun and there is a complete schematic and instructions there.

[Sir Michael]

I have a gun that has two screws that adjust the set trigger.  One, in the trigger plate adjusts the pull on the trigger (length of the pull) the second, is on the tumbler adjusts how much of the sear engages the tumbler.  For this type it is a balancing act between the two.

[melsdad]

Sorry guys no set trigger on my trade rifle. Since I have posted this question a few months back. I have got my trigger to were I like it thanks to all the help from the folks of the TMA.

[vermontfreedom]

can someone post a picture, a link to a picture, or a schematic of the working side of a lock with sears and tumblers and flys indicated

some of us newbies might benefit from a little instruction in the names and parts

thanks,

[Sir Michael]

Here's a couple of links that should be able to answer your questions.  If they can't you ask away here.

http://www.howstuffworks.com/flintlock.htm

This one also goes into all sorts of other things as well.  

http://home.insightbb.com/~bspen/

 

[Captchee]

here you go VF
Percussion Lock Terminology
http://members.aye.net/~bspen/percterm.html

Flint Lock Terminology
http://members.aye.net/~bspen/flintterm.html

Basic Lock Function
http://members.aye.net/~bspen/lockfunction.html.

[Lady of the Woods]

Fantastic thread, I really appreciated all the information. My GPR had a very stout pull and ultimately was one of the reasons I traded it off. Had I known more about it at the time I could have adjusted it. (still would a been to heavy for me though)  Agree with Vermontfreedom, would love to see a picture with the sears and tumblers.
Z

[Captchee]

A- Upper limb of mainspring
 B- Lower limb of mainspring
C- Claw of mainspring
 D- Lower pivot stud of stirrup
 
E- Stirrup
 F- Upper pivot stud of stirrup
 
G- Tumbler axle/pivot
 H- Tumbler
 
I- Pawl of sear (sear nose)
 J- Sear pivot screw
 
K- Body of the sear
 L- Arm of the sear
 
M- Sear spring
 N- Sear spring screw
 
O- Bridle
 P- Bridle screws
 
Q- Hammer
 R- Hammer spur
 
S- Hammer head
 T- Stirrup arm of tumbler
 
U- Bolster
 V- Lockplate



A- Lockplate
 B- Feather of frizzen spring
C- Frizzen spring screw
 D- Mainspring retainer stud
 
E- Frizzen spring
 F- Tail of frizzen
 
G- Frizzen pivot screw
 H- Frizzen (hammer, steel)
 
I- Face of frizzen
 J- Pan
 
K- Flashguard
 L- Cock (hammer)
 
M- Lower (fixed) vise jaw
 N- Upper (moveable) vise jaw
 
O- Vise screw (cock screw)
 P- Sear spring screw tip
 
Q- Tail of lockplate
 R- Sear pivot screw tip
 
S- Tumbler screw




A- Upper limb of mainspring
 B- Lower limb of mainspring
C- Mainspring retainer hook
 D- Tumbler hook of mainspring
 
E- Cup of tumbler
 F- Tail of frizzen
 
G- Tumbler axle/pivot
 H- Frizzen (hammer, steel)
 
I- Face of frizzen
 J- Pan
 
K- Flashguard
 L- Cock (hammer)
 
M- Lower (fixed) vise jaw
 N- Upper (moveable) vise jaw
 
O- Vise screw (cock screw)
 P- Bridle
 
Q- Sear pivot screw
 R- Body of the sear
 
S- Arm of the sear
 T- Sear spring
 
U- Sear spring screw
 V- Bridle screw
 
W- Stop, upper vise jaw
 X- Cock spur (hammer spur)
 
Y- Frizzen pivot screw
 Z- Bolster
 
AA- Fly
 BB- Frizzen spring retainer stud

[Lady of the Woods]

EXCELLENT! I am going to have to pull this up at work tomorrow and print for my shooting journal. THANK YOU!
Z