Diana Diana mod 5 worn pivot

[borne2fly]

My old Diana 5 has gradually worn over the years and now shows a noticeable barrel “tip up”. This is severe enough that it shoots high even with the rear sight all the way down. I’m thinking this is due to wear and slop in the barrel hinge. The hinge bolt seems ok, so I guess the hole has worn out-of-round. Fair enough, the thing is over 50 years old.
Is there any way to adjust this? If not, would the fix be to overbore the hole and press in a bushing?

 

[beerthief]

Think you might have just answered your own question

 

[nervoustrig]

Agreed, a bushing is the best solution. Execution is key, of course...do your best to get the bushing centered on the original pivot axis. Just plunging into the obround hole with a drill bit will put it on a new axis. Milling it would be best if you have the means and motivation. Or a bit of ingenuity and caveman tools can get the job done. For example, start by carefully filing the obround into a round, biasing it slightly away from the location of the wear. That will form the basis for keeping the drill bit centered for drilling the final hole to accept the bushing. Or sometimes you can get away with simply filing or grinding a slight bevel at the edge of the hole on the side where you want the drill bit to take a bigger bite.

 

[borne2fly]

Agreed, a bushing is the best solution. Execution is key, of course...do your best to get the bushing centered on the original pivot axis. Just plunging into the obround hole with a drill bit will put it on a new axis. Milling it would be best if you have the means and motivation. Or a bit of ingenuity and caveman tools can get the job done. For example, start by carefully filing the obround into a round, biasing it slightly away from the location of the wear. That will form the basis for keeping the drill bit centered for drilling the final hole to accept the bushing. Or sometimes you can get away with simply filing or grinding a slight bevel at the edge of the hole on the side where you want the drill bit to take a bigger bite.

Yeah, this sounds like a job for the Bridgeport. I suspect most of the wear in the hole is toward the rear and downward, where it would experience the maximum force from cocking the spring. That leaves the top and front of the hole relatively true. I can indicated from those. I dread jobs like this … it’s not like I can just go get a new barrel if I mess it up

 

[marflow 777]

so, you haven't taken it apart to look
the barrel angle is controlled by the breech seal and the shims behind the Oring
if the Oring has been smash over time and there are no shims, replacing and adding could fix it but to just guess is a crazy why to go about it
so is this a Model 5 that has the plastic grip frame

 

[borne2fly]

so, you haven't taken it apart to look
the barrel angle is controlled by the breech seal and the shims behind the Oring
if the Oring has been smash over time and there are no shims, replacing and adding could fix it but to just guess is a crazy why to go about it
so is this a Model 5 that has the plastic grip frame

Yes, the model 5 with the plastic grip.
I never noticed any shims behind the o-ring. Are you saying that the barrel angle depends on the amount of “crush” of the o-ring rather than a proper mechanical stop? I’d worry about repeatability if so.
But I did notice a slight play in the barrel (not side to side, that was perfect) which would suggest a worn pivot. I haven’t mic’d the hole yet for out-of-round.

 

[borne2fly]

Yes, the model 5 with the plastic grip.
I never noticed any shims behind the o-ring. Are you saying that the barrel angle depends on the amount of “crush” of the o-ring rather than a proper mechanical stop? I’d worry about repeatability if so.
But I did notice a slight play in the barrel (not side to side, that was perfect) which would suggest a worn pivot. I haven’t mic’d the hole yet for out-of-round.

 

[marflow 777]

well the model 5-5g-6g-6m-10 all use shims behind the Oring
i have seen as many as 4 to 0
if the rear sight was on the breech block it would not matter but being on the rear of the tube it does
now has the 5 and 6's had problems with elevation, that would be a big Yes
i don't believe have read about a worn breech bolt before and or a breech that is damaged
the model 5 has a linkage pin that come right out vs the 5G that has to be pounded out
the reason is the 5G pin has splines and was press in
the barrel would not have any side movement as it has bearing washers on both side and the barrel and washers is a very tight fit in the tube end
if for some reason the washers were not installed that could be a problem and has caused damage
i don't believe the breech bolt would found, as Waffencenter gotha doesn't not list it and any replacement could be a challenge
so the old fix for the barrel shim is dental floss
you take some floss and make several loops and install behind the Oring
the Oring is a 2.5mm x 7mm 70 or 90 dura
the shims are 0.10mm thick
it take very little to change POI while adjusting your breech seal
sound hard to believe but it is the way it works

 

[borne2fly]

well the model 5-5g-6g-6m-10 all use shims behind the Oring
i have seen as many as 4 to 0
if the rear sight was on the breech block it would not matter but being on the rear of the tube it does
now has the 5 and 6's had problems with elevation, that would be a big Yes
i don't believe have read about a worn breech bolt before and or a breech that is damaged
the model 5 has a linkage pin that come right out vs the 5G that has to be pounded out
the reason is the 5G pin has splines and was press in
the barrel would not have any side movement as it has bearing washers on both side and the barrel and washers is a very tight fit in the tube end
if for some reason the washers were not installed that could be a problem and has caused damage
i don't believe the breech bolt would found, as Waffencenter gotha doesn't not list it and any replacement could be a challenge
so the old fix for the barrel shim is dental floss
you take some floss and make several loops and install behind the Oring
the Oring is a 2.5mm x 7mm 70 or 90 dura
the shims are 0.10mm thick
it take very little to change POI while adjusting your breech seal
sound hard to believe but it is the way it works

Thanks! Great info!
I’ll definitely give that a try. I like the dental floss trick but I’ll try punching out a few brass shims first.
Are those Orings still available anywhere?

 

[borne2fly]

Marflow ... would a nylon seal work?
It wouldn't be hard to spin out a few of those. Cut the correct length, and bypass the need for any shims.
And as they wear out I just pop in a new one.

 

[marflow 777]

well nylon is a but hard but it could
if you look at the seal shim total you are looking at from 2.5mm to 2.9 mm
i have a Diana P5 it was later called the 5G mag but the breech doesn't close enough and it is a metal to metal fit
i found a front sight to correct the problem and the real fix is to remove my barrel and remove material and test the problem is the barrel linkage hardware is different and one of the hardest assembles to reassemble
my point is the pistols were never prefect and the shims were the quick fix
if the Dura of the material was in the 80-90 range there is not reason it would not work and how to adjust how proud it sits could be adjusted
now i have no idea if your breech cross screw is damaged or the seal needs shimming
i have model 5's here and i could remove the screw and measure it for you and taking the barrel of isn't hard
set screw out cross screw out and i little wiggling clean inspect and see
but shimming is easy to test
https://www.google.com/search?q=met...xuAeSBsIHBzAuMi44LjHIBzA&sclient=gws-wiz-serp