MAS 1873 Revolver

[Patrick Chadwick]

The pawl/finger (why on earth hand? - but I don't make these terms up) looks odd to me in having a squared off top. The usual shape is rounded, with the round being sharper on the inner (axis) side and with a longer slope on the outer side so that it falls into the ratchet easily and fits into the "notch". I wonder if somebody though that this rounding was severe wear, and "smartened it up"?


The squared outer corner means that the pawl has to fall a long way before it clears the edge of the ratchet tooth, and the squared inner corner is going to cause lost motion, as the ratchet has to turn some way before it comes to bear, and it will tend to dig into the teeth instead of having a bit of excess motion to allow it to slide over the outside rim of the ratchet as the trigger is squeezed in more and more.

So I suspect that the finger/hand/pawl/thingummy is too short, by about 1/16" least.

As my description may not be brilliantly clear, I'll make a sketch and post it ASAP.


Watch this space!

[Patrick Chadwick]

... then maybe this will help.

If you make a copy of this sketch and square off the nose of the pawl, you can imagine what is going to happen.

a) The pawl has to drop so far for the squared end to clear the tooth of the ratchet that the inner corner is nowhere near in contact.
b) So there is a lot of lost motion before the inner corner makes contact with the face of X and pushes it up.
c) In the process, the square corner is going to gouge the face of the tooth.
d) The square corner is going to cause severe wear on the rounded outer corner of the tooth.
e) The lost motion means that the pawl will not have the necessary overtravel to keep the cylinder stop hard against the face of the notch on the outside of the cylinder as the trigger is depressed and the revolver fires.

In other words, a square end to the pawl is like mating an ACME square thread to a Whitworth nut - a recipe for fast, damaging wear.

So I find it hard to believe that the pawl is as it should be.

Test: If the pawl has the correct length, then it will slip into the notch of the ratchet with a light "snick" when the trigger is nearly fully forwards. About 1/8" from the end of travel - no more! The closer the better. If you hear this "snick" when the trigger is still noticeably depressed*, then the pawl is too short.


Try it and let me know the result.


*Just for fun: I guess it will be a 1/4" or more on your Mle 1873.

[Aragorn243]

There are two snicks. The first is 1/4-3/8 inch from the end of the trigger travel. The second is right at the very end of travel. I believe the first snick is where the pawl first engages the ratchet because if I pull the trigger there the cylinder begins to turn immediately. Anywhere prior to that and the cylinder does not move.

[Patrick Chadwick]

"There are two snicks. The first is 1/4-3/8 inch from the end of the trigger travel... I believe the first snick is where the pawl first engages the ratchet because if I pull the trigger there the cylinder begins to turn immediately. Anywhere prior to that and the cylinder does not move."


Looks like I made a good guess - the pawl is too short. You will have to build up the end by about 2mm, then file the nose to shape and shorten it by trial and error until the pawl engages as described previously - quite close to the end, but see below.

" The second is right at the very end of travel." Must be the engagement of the trigger with the hammer. I.e. full cock. This is set to happen just after the pawl has dropped into the ratchet notch, thus preventing repeated firing of the same chamber. Sounds like it is correct, so you need to set the pawl length so that it drops just before this point.


When you have done that, the pawl will have sufficient overtravel/excess motion to achieve the state shown in stage 3 of my sketch. The play in the cocked cylinder positions should be considerably less. Note that any variation between the individual positions will depend on the state of the outside corners of the teeth and the state of the locking notches on the outside of the cylinder. The notches often have slightly worn and battered edges - another reason why the positioning is better when the trigger is depressed right up to the release point and the (more or less worn) trigger stop/bolt - whatever it is termed - moves in further and achieves better engagement.

[Aragorn243]

How do I go about building up the pawl? Spot welding?

[Patrick Chadwick]

Yes, if you have the skills or know someone who has them. All it takes is a blob of mild-steel welding rod welded on to the end. Keep the shank of the pawl firmly gripped in a heat sink, as although the material will be a fairly high carbon (i.e. hardenable) steel you do not want to soften up the bearing pin.

The ratchet is probably the hardest part of the mechanism to replace, so the nose of the pawl should be softer than the ratchet, as if you have to replace anything because of wear, rather the pawl than the ratchet!


Do not try to harden the nose. In plain mild steel it will probably last for as long as you are likely to shoot it anyway. And one day, if it really is worn, repeat the process.

Once you have a good blob on the nose, then it is simply a case of file and fit. Takes a bit of time, but is not difficult.

[Aragorn243]

My son in law will be able to do it for me when he has the time. Thanks Patrick.

[Patrick Chadwick]

The best thanks you can give me is to confirm that it works better after the pawl adjustment.


Then we can get on to the fine tuning!

[Patrick Chadwick]

Aragorn, I am happy to be able to help you, and look forward to hearing how the pawl turns out.


The fine tuning will be optional, depending on results. But it can turn a revolver with timing slop into one with practically none. Get your son-in-law on the job a.s.a.p. and while he is at it, perhaps he can make up a brass or mild steel rod that is an inch or so longer than the barrel plus cylinder (so that you can pull it out if it jams) and turned to be a close sliding fit in the bore. This is the basic tool required to check the timing on all chambers - for quality and equality.

[Aragorn243]

A.S.A.P and my son in law don't match well. His work involves a lot of travel so he's not home much. My daughter has his schedule pretty well worked out when he is home. My welding projects aren't very high on her priority list. But Father's Day is coming so I might rate for one day soon.