DWM Commerical breechblock question

[saab-bob]

Hello Gents.
I need some repair thoughts on a issue with a DWM commercial.
A gun I very rarely shoot,but I would like to keep it safe to do so.
Took to range and observed the spent shells had primer deformation. Upon inspection,I noticed on the breech block face,the area around the firing pin hole is beveled? Collapsed? Worn? Metal fatigue?
Gun is in excellent shape. Non fluted firing pin in good shape.Functions great. Super accurate.(as all the 30 cal guns seem to be)
There was a thread from 2011 with a similar issue,but the OP never posted the outcome. My issue is a little different as there is very little raised area around the firing pin hole caused by dry firing.
Here are some pics. The first is a gun portrait I did. I like period accessories!
Thanks for any advice and help.
Bob

[Edward Tinker]

nice rig, nice holster

[sheepherder]

That's a head-scratcher for sure...If it had been dented OUT, I'd say excessive dry-firing...But dented IN, WTF???

I looked at the breechblock print, the cross section, and that area around the firing pin hole is the thinnest part of the breechface, but I really can't see anything that could dent it in...

The only thing that comes to mind is maybe it was dented out from dry firing and some-bubba hammered it back in...Too far...

If that was true, I would expect the firing pin to not protrude as much as it should...

Great problem! Thanks for bringing it up!

[saab-bob]

Gents.
Thank you for the feedback.
The center of the breech block face is not flat. It is sunken down.Almost like someone machined a bevel,as its very even in shape. When I look inside the breech block it doesn't look pushed in. However its hard to make out small protrusions at the bottom of a dark tube!
On the primer flow,it looks like the primer is filling in the sunken part of the breech block face.AFAIK Fiocchi is a little hot,but the gun exhibits no excessive recoil.
I have all the dies and shells to reload 30 luger,but I have a bunch of Fiocchi ammo. I bought it ,when I thought production would be discontinued.
Hmmm.
Bob
Bob

[sheepherder]

Originally Posted by saab-bob

When I look inside the breech block it doesn't look pushed in. However its hard to make out small protrusions at the bottom of a dark tube!

How about the firing pin??? From the print, it looks like the entire front slope of the firing pin would strike the inside of the breechblock. If that area is pushed in, it should leave a 'wear ring' on the firing pin. If it's worn or metal has been somehow removed, there shouldn't be any wear...I'm thinking...

The only thing similar to this that I've ever seen is chamber/bore erosion...

[John Sabato]

The firing pin hole in the breechblock "appears" to be oversize... at least to me.

I think I would find some hole gauges or decimal sized drill bits and find out what size the hole is and compare it to the Luger blueprints or other some other Lugers. Could be someone may have unintentionally damaged the breechface in an attempt to clean up burrs on the firing pin hole...

If it turns out to be critically oversize, it could be repaired by microwelding and re-drilling the firing pin hole to specifications.

[rhuff]

As noted above, this is a most interesting condition. On examining the fired primers, it is obvious that there is a depression of the breechblock face in the area of the firing pin hole. It seems to be very uniform. It is as though someone used a tapered punch/drift and struck the area surrounding the firing pin hole., basically over correcting the problem.

I had a protrusion of material surrounding the firing pin, supposedly from dry firing, and corrected it with a flat faced brass drift and a hammer.......now the breechface is uniform. My spent primers look normal.

If you are overly concerned about it, and wish to continue shooting it, one could fit an aftermarket breechblock just for firing.

[John Sabato]

I just checked the blueprints (If you owned a set you could check them yourself --see the For Sale forum for how to obtain them...)

The firing pin hole size SHOULD be 1.6 mm + or - 0.05mm tolerance There should be no depression around the hole.

[John Sabato]

Hello Rick... just cause you asked... (and I bet you DO have a set of the blueprints tucked away)

[sheepherder]

BTW, Bob - Is your extractor chipped on the left side???

[saab-bob]

Thanks for all the help gents!
Just got back from a road trip to Los Angeles for work.Bad traffic
John.
Thanks for the info on the measurements. I will try to do some checking.
This sounds like a interesting problem,to bad it happened on one of MY guns!
Bob

[G.T.]

Try to determine if it was made that way..or dented in from flat... if the latter, I would remove the extractor, and with the breechblock set flat on it's face over a brass plate, take an old firing pin, and use it as a punch form to drive the depression back to flat from the backside??..... Maybe not the best, but it's what I would try...Best to all, til...lat'r....GT....

[saab-bob]

Rich
Looking closely at the extractor,it looks free of any serious chip. Perhaps a tiny bit around the front edge.
The firing pin seems to fit tightly in the firing pin hole on the breech block face?
Will get some more pics tonight!
Thanks
Bob

[sheepherder]

Originally Posted by saab-bob

Rich
Looking closely at the extractor,it looks free of any serious chip. Perhaps a tiny bit around the front edge.

Must be an optical illusion - In your pic, it looks like part of the left corner is broken off...

[aldo35]

The first picture of the spent cases look to me like all the primers have a convex shape suggesting some blow back. To my eye they appear to be raised as opposed to a flat surface. Perhaps these cartridges were to hot for this pistol and the primer caused the depression in the breech block.

You show a box of Western ammo. Were the cartridges you fired reloads or the factory ammo?

Aldo35

[hayhugh]

aldo35 , yes sir, that is what I have been thinking right along.

[JD]

I had, at one time, a Beretta 92F that came from the factory with a firing pin hole dished in like your luger. It never had an effect on functioning, so I just left it as it was. I have no idea why it was that way....

[saab-bob]

Aldo & Hugh
Thanks for the idea. So perhaps the expanding primer is causing or has caused the indent in the breech face?
The ammo I was shooting is factory loaded Fiocchi FMJ. I understand its loaded a little hot because it is also used for those pesky SIGs, Browning HI Powers and Benellis that have barrels in 30 luger.
I have not shoot this gun much at all. Maybe 50 rounds since I have owned it.I wonder if a PO put some hot reloads thru it?
Verrrrrrry interesting.
Bob

[ithacaartist]

This dent is puzzling, indeed. Looking at the cross-sectional drawings, this area of the breech block looks pretty beefy, despite the tapered relief hole/relief on the inside for the f.p. If the tip of the firing pin conforms to the shape of the hole, then the force of impact is transferred over a rather broad area. For a breech block to become pooched out around the hole for the striker's tip, it would be the corresponding area on the striker itself that would have to be the point of contact/impact--and the rest of this mating would need to not touch/hit. This is the only way I could see for significant material around the hole to be displaced/peened--by this area, alone, absorbing the bulk of the blow. And if the depression around this one's hole was caused by a punch, in an attempt to correct the former, where in heck does all the material go? How frequently is this deformation of the breech block face encountered?

[sheepherder]

Originally Posted by ithacaartist

This dent is puzzling, indeed.,,if the depression around this one's hole was caused by a punch...

How about if it was extensively dry fired, and the owner tried to remove the resulting 'ridge' by use of a round stone in a drill...or even a drill bit...