Anyone else having second thoughts on the MR73?

[45dotACP]

After seeing some of the problems people have had...I really did wish the MR73 was some sort of mithril pulled from the depths of moria and forged into this legendary weapon.

But it's not. It's just, after all, a double action revolver.

And a double action revolver will never be as durable, simple or reliable as a modern semi auto.


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[jetfire]

Pretty sure CZ discontinued the DW 715 a couple years ago.

Not really, they stopped selling it as an individual item and brought it back as the pistol pack with three barrels.

https://danwessonfirearmstore.com/715-revolver/

[jtcarm]

Not really, they stopped selling it as an individual item and brought it back as the pistol pack with three barrels.

https://danwessonfirearmstore.com/715-revolver/

Yep, the PPs I’ve seen run about 2K.

[jetfire]

Yep, the PPs I’ve seen run about 2K.

That is a very expensive pp

[jtcarm]

That is a very expensive pp

Yep.

I didn’t realize the 715 was so heavy.

My experience was with the 744, which you expect to be heavy.

[Scal]

I believe Caleb's issues were not due to a bad heat treat on the cylinder latch he got, but due to the geometry of the cylinder notch ramps and the latch. Probably fixable, but I'm not really interested in doing that. Also, the MR73 I've handled wasn't as smooth as my cleaned-up M&P 340. (And my GP is similar to the J, although a little stackier/clunkier in its progression.) So whoever wrote (I read it somewhere) that an out of the box MR73 was smoother than an S&W could ever be is proven wrong by guns I've held in my hands. Plus there's the serrated trigger. But the guns are beautiful.

What do you suspect was off as far as cylinder ramp/notch geometry? I would be interested in hearing about it. Your 340 thread was great, by the way.

[OlongJohnson]

Discussed it as a hypothesis in the Beretta/MR73 thread:

Is the out of time exhibited with it skipping chambers in rapid DA (dry-hopefully) fire? Any peening of the cylinder notches? Will be curious to see photos of the parts you replace.

One interesting detail I've noticed is that the ramps leading into the cylinder notches on the MR73 are kinda oval-shaped rather than straight as they are on S&W and Ruger revolvers, as if they were made with an olive-shaped cutter rather than a straight end mill. The MR73 ramps actually curve back downward as the cylinder stop approaches the notch. (A note on nomenclature: I am saying "downward" as the notch is oriented relative to the frame when the stop is moving "up" to engage the notch, but it would be "upward" if you think of "down" as into the notch, oriented the way you typically view a notch.) At speed, this could be expected to have the effect of dynamically reducing the engagement of the stop with the approaching far edge of the notch. I've worried about that and thought about reworking the notch ramps.

On my GP MC, there was a burr or raised lump at the end of each ramp where the ramp met the notch. As the stop rode the ramp up into the notch, at speed, the burr/lump would kick the hand back downward, reducing the engagement of the stop with the approaching far edge of the notch. Initially, I had some moderate peening from dry fire. When I noticed the peening and the raised burrs, I stoned the burrs out of the ramps so the ramps go smoothly all the way to the end and have a clean drop into the notch. I also stoned off the peening (love brushed stainless here) so the far side of the notches was flat/flush with the OD of the cylinder and looked new. Immediately on reassembly, I noticed the sound of the notch hitting the stop was just a little cleaner and more solid without that micro-tick when the stop hit the lump. Since then, I've done a ton of DA dry fire and there is zero additional peening.

Pleased with that result, I did the same thing on my M&P 340. You can see a sliver of silver on the blackened stainless cylinder at the end of each notch ramp, but I'm OK with that.

Essentially, I've put "deburr cylinder notch ramps" on my general revolver pre-use prep checklist. It's a high level of commitment to act on a belief that I know how to design the cylinder notch lead-in ramps better than Manurhin/Chapuis. I'm also kind of waiting for someone to come along and explain what I don't understand that makes the MR73's notches actually correctly designed.

You can see what I'm talking about with the close-up photo of the cylinder in Caleb's review at https://www.targetbarn.com/broad-side/manurhin-mr73/

Pic here: https://blogcdn.targetbarn.com/broad...incylinder.jpg

The ramps, rather than being ramps straight down into the notch, are more divots that actually rise back toward the outside of the cylinder as you travel closer to the notch.

I've seen some turn lines on MR73s that seem to show the contact point rising as it gets closer to the notch.

Also, the cylinder stop/latch is flat across, where S&W and Ruger stops are angled. The American design allows the leading side to begin dropping into the notch before the trailing side gets all the way to the notch (which is just a few thousandths of an inch before the leading side reaches the far side of the notch).

TLDR: I think that due to the design of the parts, the dynamic engagement of the cylinder stop in the notch when firing quickly in DA is inadequate and leads to the stop being peened, as Caleb observed. If firing more slowly, the stop is likely more robust than S&W or GP100 stops, as it is notably wider.

If I was to attempt to tune one up, I would look very carefully at all the geometry and figure out a target set of dimensions aiming to balance allowing the stop to engage the notch as much as possible on the leading side in dynamic conditions, while still maintaining enough engagement of the trailing side to securely hold against the rebound when the cylinder bounces back off the stop, so it doesn't end up disengaged/misaligned in the backward direction. It would mean remachining the ramps (possibly in a mill, possibly just working them a little with hand tools) and tapering the stop. It's certainly possible it couldn't yield a full cleanup of the existing ramp surface, which would leave it looking altered/Bubba'ed no matter how well it worked. In any case, one would have to cold blue the notches or reblue the whole cylinder, and it might be difficult to find someone to match the Chapuis bluing here in the US. If someone was willing to sacrifice the cosmetics of a cylinder and the labor, they might be able to achieve a result that could be demonstrated to be superior and get Chapuis to adopt it as an engineering change. Might.

Or, it could be that there's some reason that wouldn't work, which I haven't discovered because I haven't gone down the road and found all the bridge trolls.

[MandoWookie]

The absolutely bonkers (in a good way) Chiappa Match Master 6

What's your opinion on the regular Rhino?

[jetfire]

What's your opinion on the regular Rhino?

I've never seen one hold up to a really rigorous firing schedule; the action is incredibly complex when compared to something like a S&W. The two I have shot exactly 250 rounds each and currently live in my safe. I keep thinking I want to really wring one out, but when presented with other projects it never really gets done.

[zeleny]

Speaking of the MR73, I finally got all my thoughts on the gun collected together in one place and published.

Here's the Manurhin MR73 Review

I really did enjoy shooting it, and really the only downside is I have a bunch of competition gear for K-frame sized guns and I don't own a K-frame.

Anyone want to sell me a Combat Masterpiece?

“It’s made exactly the same in 2021 as it was in 1973, and it represents the pinnacle of what was possible for a duty gun in 1973.” Not so. The MR73 action had its original music wire cylinder hand spring that allowed the cylinder hand to bounce in the recoil cycle replaced by a better tensioned leaf spring. The top sideplate screw liable to loosen in the recoil cycle was deleted in favor of a wedged sideplate top arrangement. The forged tapered trigger return spring that was found to fatigue in service was replaced by a stamped spring of uniform thickness. Lastly, the original needle-nosed cylinder hand was replaced by a chisel-nosed design, with the insular cylinder ratchet correlatively replaced by a conventional star-shaped variant. Cosmetic changes include the replacement of a solid front sight retaining pin with a rolled pin, the omission of longitudinal ribbing on the grip frame, and the plain Swiss-made rear sight giving way to the current overhanging while dots variant. See a detailed account in my article on the Manurhin MR73 design and construction.