Lock work?

[smid1584]

There's always talk on here of certain locks needing work etc...
I looked through the tutorials and couldn't find anything..
I'd love to learn how to make my locks function better..faster..etc....

[rich pierce]

Most locks work well out of the box nowadays. Removing friction is the most common and helpful step for any lock.

Mainspring. Look to see if the mainspring arm is scraping the lock plate. Fix that by filing back the spring arm 0.005” or so where it’s rubbing.

Bridle. See if, with the mainspring and sear spring out, the cock moves freely through its cycle. If not, is the bridle impinging on the tumbler?  If it is you may have the bridle screws over tightened. You could remove the bridle and see if the inner surface needs polishing. Probably not. In general do not polish the tumbler axle or axle hole in the bridle because you risk making the lock sloppy.

Tumbler. Don’t do much here except make sure the arm contacting the mainspring hook is square and polished. Be very reluctant to polish the tumbler shaft in the axle that rides in the lockplate or in the bridle. If you feel bad friction and see 1 obvious burr, fix that. Otherwise do the toothpaste trick. Degrease the lockplate and bridle tumbler axle holes, degrease the tumbler, slather toothpaste on tumbler surfaces and in axle holes, re-assemble tumbler, bridle, bridle screws and cock, and cycle the cock fore and after a couple hundred times. You should see some grimy toothpaste. It has helped the surfaces mate without changing dimensions enough to measure.

Sear/ sear spring. See if the sear pivots effortlessly on the sear screw. If not, toothpaste treat it. Next, polish the top surface of the sear, where the toe of the sear spring rides. Always keep surfaces square and remove as little steel as possible. Now check the sear spring arm is not scraping the lockplate. It rarely is but file the inside arm to fix that as needed. Now make absolutely sure the toe of the sear spring, where it rides on the sear arm, does not push up against the hump of the sear that is around the sear screw.  You want minimal but visible clearance here else the sear spring sort of jams the sear. Next make sure the toe of the sear spring which rides on the sear arm is polished.

Frizzen spring. Make sure the frizzen spring arm is not scraping the outside of the lockplate. Polish the top surface where the frizzen toe rides.

Frizzen. Test free movement of the frizzen on its axle with no frizzen spring present. If a problem, look for any single burrs and fix. Then give the toothpaste treatment.

Wash everything, lightly grease, and re-assemble the lock. It should have reduced friction and feel smoother when you bring to half and full cock.

[TommyG]

X2 for everything Rich has already mentioned.  In addition, I like to check for gap or daylight where the frizzen meets the pan.  I'll do this with the frizzen spring removed using inletting black to highlight any high spots.  Currently I carefully remove them by lightly stoning the pan and lightly sanding the frizzen on a piece of glass using emery paper, until I no longer can see any daylight on the frizzen pan joint.  I am curious as to how others here do this as to not disrupt the plane or top of the pan.

[Mark Elliott]

X2 for everything Rich has already mentioned.  In addition, I like to check for gap or daylight where the frizzen meets the pan.  I'll do this with the frizzen spring removed using inletting black to highlight any high spots.  Currently I carefully remove them by lightly stoning the pan and lightly sanding the frizzen on a piece of glass using emery paper, until I no longer can see any daylight on the frizzen pan joint.  I am curious as to how others here do this as to not disrupt the plane or top of the pan.

I have tied to improve the fit between the frizzen and the pan, but have given up as it is geometrically impossible without changing the location of the frizzen screw at the same time.   All I  do is polish the pan the same as the rest of the lock plate.   Once the lock is assembled,  it is next to impossible to change the fit of anything.   Basicaly,  I just stone bearing surfaces to make them as slick as possible.   Also, flys are frequently too high and need some stoning; that,  or the top of the sear.

[Mike Brooks]

Generally, if you buy high quality locks like Chambers and most locks from Davis, you'll rarely have anything to do to them. All the polishing is already done. If I received a Chambers lock with a poor fitting frizzen, (I haven't in 37 years of using his locks) I'd send it back for a replacement.

[Jim Kibler]

The amount of work that needs done is related to how demanding you are.  I recall a post years ago where Mike shared his thoughts about using locks with little to know further work.  Bill Shipman kindly responded that for the level of guns and the price point he sells them at, he feels work is necessary.  I think others who build similar quality guns would agree.  When building high quality custom guns it wan't uncommon for me to spend a half a day or even a day working over a lock.

With this all said, locks are a great value for the work in producing them and I'm not knocking the manufactures. 

What needs done depends highly on each particular lock.  You can't describe it in a post like this.  You really need to know what the ideal lock is and then correct anything that doesn't match this.

Heck, I remember reading not too long ago, Jim Chambers said that when he builds a custom rifle, he assembles a lock carefully for this project rather than using a production piece.  Nothing wrong with a production lock, but if your willing to spend more time, they can be better.

Jim

[Dan Fruth]

Great questions and great answers. Adding to Jim kibbler's answer, I now case harden the lock plate around the tumbler hole, then polish. This seems to help reduce drag

[Tim Crosby]

 Take a look at this:

  http://americanlongrifles.org/forum/index.php?topic=2585.msg24681#msg24681

  Tim C.

[Chris Evrard]

All good advice. Maybe I should make a video on lock tuning??

As mentioned stock locks from quality builders should throw good sparks and work just fine when you get them. If not then return it for a replacement.

A stock lock is analogous to a stock car. It works just fine. Sure it can be faster, it can handle or brake better and all the tips mentioned above are great ways to make it do just that.

As to frizzen fitting (I have a batch of 30 Small Silers I will be fitting frizzens on in just a few minutes) the method outlined above is just about what I do. Although I do keep the frizzen spring in place. It gives you the actual pressures on the pivot screw, frizzen, etc. that you will have on your finished lock and helps to take up the slack between the frizzen through/pivot hole and the pivot screw itself.

I color the pan (which has already been milled flat at this point) in prussian blue, and gently close the frizzen to transfer the blue from the pan to the frizzen surface. Then open the frizzen and remove the high spots with a sharp file. Repeat, repeat, repeat until you get a nice blue ring around the frizzen surface. Then wipe it down and check it for gaps behind a light source.

After the frizzen has been hardened this process gets a bit more tricky. And sometimes the frizzen moves during hardening... grrrrrr. I know my pan surface is flat, so I don't want to "work" it. I'll use the same method above with the blue but I'll use a stone burr on a Foredom tool (dremel will suffice) to knock down the high spots. Go slow! Check your work with the light frequently.

CE