Manurhin MR73 not rotating cylinder at slow speed cocking

[raubvogel]

I must warn I am not very knowledgeable in the way of wheelguns, so do bear with me and my stupidity. So I have a Manurhin MR73; it is probably not the best brand out there but that is what I got and it fits my hand nicely. Kinda massive though, comparable to a 1911 in size. Anywhoo, I took it to the range and shot a few rounds. What I noticed is that if I pull the trigger normally (for me), it fires and the cyclinder rotates to the other round as it should. But if I pull it deliberately and slowly, the cylinder does not fully rotate to the next round. It almost feels like whateve ris supposed to grab the cylinder and rotate it is not doing its job.

Since I am clueless, I decided this was a good opportunity to see how a revolver mechanism looks like. So, I took the side panel off:

What should I be checking for?

 

[rswartsell]

I think you have the wrong idea about Manurhin. The are a super premium arms maker (Chapuis Armes) that make fine double shotguns and hand crafted revolvers. Your example should easily be worth repairing. Unfortunately I have no earthly idea who to suggest.

http://www.chapuis-armes.com/26-manurhin

 

[Jim K]

The Manurhin lockwork is basically the same as that of the S&W, so any gunsmith worth his workbench should be able to figure out what is wrong.

To refer to the picture, the hand that turns the cylinder is the long vertical arm reaching up from the back of the trigger. It is pushed into engagement with the ratchet at the back of the cylinder by the flat spring which is part of the flat slotted part at the side of the hammer. That spring could be weak or broken, and is the first place I would look for the problem you describe.

Jim

 

[rcmodel]

It looks dry as a dinosaur bone in your photo.

Maybe some oil on everything that moves would be the first thing to try?

rc

 

[murf]

that cylinder looks well used. the bolt notches look rough, too. maybe the hand is worn out and won't carry up the cylinder all the time.

murf

 

[MrBorland]

So I have a Manurhin MR73; it is probably not the best brand out there

ok, I just cleaned the coffee I sprayed on my keyboard. Some may argue that there's one better, but I'd consider an MR73 a bona fide top shelf revolver. I'd love to find one myself one day. You lucked into a mighty fine revolver!

Anyhow, as others mentioned, a lubing might help. The hand may also be a bit worn and/or short. If the lockwork is similar to a S&W, a decent gunsmith ought to easily remedy the issue.

 

[sgt127]

Thats very Smith and Wesson-ish inside. I'm guessing the hand is either too short (colt design) or too thin (Smith design) and not carrying up properly.

Even if the ratchets are worn a little on the star, an oversized hand would fix it. Now, the only problem is, I have no idea where one would find an oversized hand.

Thats a nice gun by the way.

 

[Jim K]

The hand on a Manurhin would be easy to make if necessary. Unlike the S&W, which has two pins and some complicated curves, the Manurhin has only one pin (the spring is a separate part and not inside the trigger) and it is just loose on the hand.

Jim

 

[MrBorland]

I'm wondering if the hand, if too short, couldn't simply be peened a bit for a little extra length.

 

[PzGren]

Does it also happen when you operate the gun in D/A?

A problem with the hand is usually leading to late timing in D/A before it is noticeable in S/A. My guess is that the spring that pushes the hand through the window is weak, since this happens when you slowly cock the hammer. Proper lubing should also help with a slightly weak spring but won`t do magic.

It is the leaf spring at the rear of the hand. I am not sure if a MR73 hand can be fixed by stretching the hand, like it can be done on a Colt or if the thickness of the hand is responsible for proper timing or issues, like with a S&W.

 

[raubvogel]

First of all, thank you for all the replies. And I do apologize for taking so long in replying.

PzGren, it happens in both SA and DA modes.

The star on the back of the cylinder is not as tall as the one in a S&W but looks machined from the cylinder, while the S&W seems to be welded into place. Still I do not see wear nor on the hand; I can post picture of both because I might be missing something.

One of the things I did -- and the reason why I was able to take those pictures -- was to press the back of the spring, adding more pressure to the hand, and then slowly pressing the trigger in both SA and DA modes. I did not mention that before since I thought many would call out as a really stupid and dangerous thing to do; I did say I am not knowledgeable in revolvers. Anyway, the extra pressure caused the cylinder to rotate properly at all times. I think that would make me consider weak spring.

 

[5-SHOTS]

The Manurhin MR73 is one of the finest revolver on the planet. When 100% it has one of the best looking blue on earth. The chambers are proof tested for pressures well well over the ones recommended for the .357Mag.
I rank it just under the Korth revolver. It's a K-frame size revolver.
I was just going to tell you to check the hand's spring but it seems you have already discovered the problem.
My advice is to have it inspected by a good gunsmith anyway.

 

[beag_nut]

When I look as closely at the photo as is possible (not in the best focus), the bolt stop notch on the cylinder looks worn (rounded edge). The stop bolt might be getting hung up on the edge. Also, the hand (aka pawl) may not be sufficiently advancing the cylinder during "low speed" , as was previously mentioned, but he inertia of the "rapidly" rotating cylinder might be just enough to advance to the point where the bolt would drop into the notch. I seem to remember such a problem (and diagnosis) on a long-ago forum somewhere.

 

[Jim K]

Hi, raubvogel,

FWIW, the ratchet of the S&W is machined as part of the extractor, the same as the Manurhin. I have never seen or heard of a revolver with the ratchet welded on.

Jim

 

[Panzerschwein]

While I don't think a Manuirhin is worth it's weight in Colt or Smith, either or the two fluent afflunetial gunsmith's should be able to ascertain any inherent flaw the revolver in question may be of undertaking too.

YMMV.

-Cdill OUT

 

[Jim K]

They did some design tradeoffs that I am not sure bought them anything. One was putting little wheels on the rebound slide to solve the almost non-existent problem of friction in that area. (Merely machining away part of the bottom of the S&W slide will do about the same thing.) But by installing those rollers, they removed the possibility of using a coil spring inside the rebound slide (as S&W does) and had to use a flat spring at the rear, not as good a solution, IMHO. Also, they use a flat spring to power the hand, allowing the elimination of some complex machining in the trigger, but creating the problem the OP is experiencing.

Jim

 

[natman]

First try oiling the mechanism. Then a photo of the extractor star and the tip of the hand would be helpful.

 

[barnbwt]

Raubvogel, you didn't just sell your MR73, did you?

j/k --it's good to hear about the few possible issues to look for when my 'new' old, beat up surplus MR73 arrives next week.

"They did some design tradeoffs that I am not sure bought them anything."
I don't know nearly as much about revolver lock work as I should, so I don't know if the S&W design concept could be adapted to similar specs, but the MR73 appears to have exceptionally short DA and SA trigger travel. Most reviews/videos are of the mint condition commercial guns that have been well cared for, but even the beaters have the short (but heavier) trigger action. The single action in particular looks crazy short, almost like a rifle trigger from what I can tell. I don't know if the Smith could be retooled (obviously by a redesign no one would pay for) to do something similar and still have a reasonable trigger weight, or if the less-advantageous leverage of a shorter trigger would necessitate something like a roller bearing and its attendant design consequences. So I agree that the design has tradeoffs (I would argue that cost was the biggest one by far, though), since all designs do, but it does seem the French handgun does some things not seen in competing platforms (being built like a brick birdhouse being one of them). The S&W guns preceding it were getting shot loose too quickly, and the MR73 did supposedly resolve this problem (it wouldn't surprise me if it was a largely political decision, though, just like every other military 'weapon reliability' scandal)

TCB

"While I don't think a Manuirhin is worth it's weight in Colt or Smith"
I don't think gold is worth it's weight in Colt at this point. Pythons are getting --scratch that; have gotten stupid expensive in the last few years. I say this as a guy who dropped three grand on a Mateba; at least that gun actually is rare, while still being well made/blued and in great condition.

 

[raubvogel]

The pictures are crappy because they were all taken with my phone and inside. I will try to find my proper camera and take some pictures with it.

natman, I did spray Remoil in the mechanism, but that did not seem to have improved anything; I actually had mentioned that in my *original* last reply but lost that (and learned to type it in something like vi and then copy it here). I probably also forgot to mention something else since my *replacement* last reply looks half of the size of the original one.

Jim K, I will ask my friend who has the S&W revolvers to take a picture of the back of his cylinder's extractor. Maybe it was the light when we compared both of them.

Cooldill, your opinion reflects what I heard from the local gun community, i.e. A Manuhrin is French, which means a flawed (I would go even further and quote them as saying "it is impossible to improve on a S&W just like it is impossible to make a better pistol than a 1911") POS that is only in one piece because it was "never fired, dropped once." And that the only use for one is to melt down not to make a S&W but to make the trash can to hold the dirt from cleaning a S&W. I guess that is what attracted me to it; after all, my other revolver is an equally unproven and unreliable M1895 Nagant (let's not even mention my pistol collection ).

But then again, I found out the nearest gunsmith will not fit a barrel to my Auto Ordinance 1911A1; it was below his skills. So I need to find a more willing gunsmith.

Update: Found this gunbroker auction with really nice picts: http://www.gunbroker.com/Auction/ViewItem.aspx?Item=449313688. I will download them so I can compare with mine.

 

[MrBorland]

Cooldill, your opinion reflects what I heard from the local gun community, i.e. A Manuhrin is French, which means a flawed

Again, the MR73 is a premium revolver. You were fortunate to have stumbled on it. Your MR73 developed a minor problem, but that doesn't make it as "unproven and unreliable" as your Nagant, which is several leagues under your MR73. If you don't want it, lemme know.

 

[raubvogel]

Pictures as promised:

Looking at the pictures from the gunbroker auction closely, it seems the extractor was replaced: the tips of the star on the extractor are narrower than the other side in the cylinder. And the rachet looks very different.

 

[natman]

The star arms at 9 and 11 o'clock look worn. The tip of the hand doesn't look very square either, although it's hard to tell exactly from pictures.

Time for a good revolver smith.

 

[bc1023]

So I have a Manurhin MR73; it is probably not the best brand out there but that is what I got and it fits my hand nicely.

Its actually one of the best revolvers in the world...

Your local gun community is clueless.

 

[bragmardo]

One of the things I did -- and the reason why I was able to take those pictures -- was to press the back of the spring, adding more pressure to the hand, and then slowly pressing the trigger in both SA and DA modes. I did not mention that before since I thought many would call out as a really stupid and dangerous thing to do; I did say I am not knowledgeable in revolvers. Anyway, the extra pressure caused the cylinder to rotate properly at all times. I think that would make me consider weak spring.

You need a new spring, is all. Call Chapuis -- Tel : (33)04 77 50 06 96. Fax : (33)04 77 50 10 70.

 

[raubvogel]

I knew I forgot to do something: I did contact them early this month; they replied on Nov 3. So, they said they cannot sell me a new ejector since it is machined with barrel during manufacture. But they can not also sell me the barrel + ejector since it has to be fitted in the gun and then proofed once more in their test range.

Well, I do not know what kind of bag of cats I would get if I had to ship the revolver back to them and then have them ship it to me. I wonder if ATF would let this go as a "shipped back to manufacturer." I need to find out.

In the mean time, I ordered the hand/paw + spring. Which they told might need to be fitted by a qualified (!) gunsmith.

They sent me an email on Nov 7 telling my my bank transfer (they would not take credit card) was successful and will be shipping the parts the next day. I wonder how long it will take to get here...