Diana Model 5G malfunction.

[Steve Zodiac]

Can anyone offer a diagnosis ?

My recently acquired Mod 5G has tonight developed an issue.

I've probably put about 100 pellets through since I purchased the pistol on BBS, the previous owner did a reseal and the pistol shot very nicely on my 6 metre cellar range.

Fast forward, tonight I put about 20 pellets down then when I came to shoot the trigger seemed ok on first stage take up then it was as if locked. Didn't want to force it obviously so re broke the barrel and the gun instantly went off.

No pellet discharge as the barrel was in the open position but not at full cock , just open pre spring cocking tension .

Re cocked , aim at target , nothing, locked trigger.

Open pistol and pow !

Same story.

Put gun down and make a brew.

Any thoughts ?

[ggggr]

Can anyone offer a diagnosis ?

My recently acquired Mod 5G has tonight developed an issue.

I've probably put about 100 pellets through since I purchased the pistol on BBS, the previous owner did a reseal and the pistol shot very nicely on my 6 metre cellar range.

Fast forward, tonight I put about 20 pellets down then when I came to shoot the trigger seemed ok on first stage take up then it was as if locked. Didn't want to force it obviously so re broke the barrel and the gun instantly went off.

No pellet discharge as the barrel was in the open position but not at full cock , just open pre spring cocking tension .

Re cocked , aim at target , nothing, locked trigger.

Open pistol and pow !

Same story.

Put gun down and make a brew.

Any thoughts ?

I've done a few of these pistols but not a favourite of mine. I'd try adjusting the trigger adjusting screw after undoing the lock screw and see if that makes any difference.
Then I'd separate the housing from the cylinder and trigger and see if the the trigger spring or sear spring are broken. After that I'd remove the mainspring from the gun and then have a play round cocking and de cocking the gun ( Or pushing the piston forward when you have pulled the trigger). You might see something is bent or worn.
Usually on a gun doing this , i'd say the piston is not fully engaged , probably as either where the trigger holds or when the cocking arm pushes on the piston is worn.
As the pistons on these can be hard to get out, as they get to a point in the cylinder where is is difficult to find anywhere to tap/ push or pull, I'd be looking at burrs round the 2 cocking slots on the piston.
I'm sorry i cannot be more helpful.

[Geezer]

Some kind of trigger/sear wear or crud issue.

Take apart (easy but slow, an annoyance on these is that any meaningful strip is a total strip), check, clean, if no obvious damage, re-lube, re-assemble.

Boring but necessary.

If problem persists, seek further advice or assistance.

Sorry not to be more helpfully helpful.

[Steve Zodiac]

I've done a few of these pistols but not a favourite of mine. I'd try adjusting the trigger adjusting screw after undoing the lock screw and see if that makes any difference.
Then I'd separate the housing from the cylinder and trigger and see if the the trigger spring or sear spring are broken. After that I'd remove the mainspring from the gun and then have a play round cocking and de cocking the gun ( Or pushing the piston forward when you have pulled the trigger). You might see something is bent or worn.
Usually on a gun doing this , i'd say the piston is not fully engaged , probably as either where the trigger holds or when the cocking arm pushes on the piston is worn.
As the pistons on these can be hard to get out, as they get to a point in the cylinder where is is difficult to find anywhere to tap/ push or pull, I'd be looking at burrs round the 2 cocking slots on the piston.
I'm sorry i cannot be more helpful.

I was going to make my first strip and rebuild on an old Airsporter MK6 this winter , but I shall now throw myself into this 5G, try and see if I can solve the problem.

The pistol is in what looks like brand new condition , the previous owner said it had very light use, he also resealed the gun on advice from BBS prior to sale. I'd guess something has maybe failed , but it is only a guess. What I did notice was the trigger ( second stage ) was extremely light, almost hair trigger. I didn't try knocking it o see if that was enough to set it off , maybe I should of. I'll try the trigger adjustment first tmrw. I think the instructions are in the box..

Just seemed very odd the gun fired upon breaking the barrel.

Thanks for the advice.

[Steve Zodiac]

Some kind of trigger/sear wear or crud issue.

Take apart (easy but slow, an annoyance on these is that any meaningful strip is a total strip), check, clean, if no obvious damage, re-lube, re-assemble.

Boring but necessary.

If problem persists, seek further advice or assistance.

Sorry not to be more helpfully helpful.

Thanks for the advice, its all appreciated.

I'd be surprised if it was wear/ crud as the previous owner did a strip and reseal following advice received here on BBS prior to the sale. Also I don't think the pistol has had much use at all looking at its condition..

I'll try the trigger adjustment , then if no special tools are needed ??

I'll take it to bits and see what it throws up.

Shame really, it was shooting rather well and I was actually hitting the black with it !

[crowbar]

Is this the 3 ball trigger ?

The double bolt that holds the action and stock together has a nib on the end which restricts the forward movement of the outer sleeve when the trigger is pulled , if this has worn or isn't screwed in tight the sleeve can over ride the travel
and stick and when you try and recock goes off .

[Benelli B76]

Is this the 3 ball trigger ?

The double bolt that holds the action and stock together has a nib on the end which restricts the forward movement of the outer sleeve when the trigger is pulled , if this has worn or isn't screwed in tight the sleeve can over ride the travel
and stick and when you try and recock goes off .

No, the model 5 trigger is one of the simplest designs with few parts. They are very easy to install like the model 6, and I don't know why they replaced it in the more complicated model 10. The 5G looks the same according to Chambers parts diagram, I would suggest trying to re-adjust the let-off as mentioned above and also check the spring CS186 is installed correctly.

Baz

[Steve Zodiac]

I've made a start.

Grips and frame off so I'm left looking at the action, trigger upper most seeing if I can work out what is or isn't happening here.

Action uncocked can feel under spring load stage one and two of the trigger movement , so that spring is operating.
The release arm ( ? ) also sprung loaded by the rear most spring is also operating ok. The only way I can manually push release arm over the sear is when I fully depress the trigger to the end of stage two travel, it won't go behind the sear at stage one only.

I can feel/see stage one and two ( release ) as normal.

I can see the small nipple on the trigger assembly ( front ) disappear into the sprung loaded adjuster screw and return under spring pressure. Normal I assume ?

The sear behind the trigger looks polished but in shape , is this a normal friction area for the release arm ?

If I open the barrel to first stage but not cock. I can only reach stage one of the trigger pull, and the nipple doesn't enter the the adjuster screw I can only feel resistance but not sprung loaded resistance .

I've not cocked the pistol yet again as I'm trying to avoid last nights two dry fires on opening the barrel.

It may well be the only way to see what's happening and if its just trigger adjustment needed ?

Dies any of this make any sense ??

Thanks for any assistance .

[Steve Zodiac]

Do yourself a favour and take the mainspring out. It is a lot easier and safer to see what is going on. Dont forget the little grubscrew in the endcap.

I've pulled the plastic dust cap off at the rear if that's what you mean ? No grub screw.

I'm seeing inside the cylinder , but it looks like.

A) ill need a spring compressor

and

B) I'll need to invent some sort of tube tool with cut outs to go over the retaining pin and put pressure on the spring so I can remove the pin.

Think a spring compressor maybe in order .

[Geezer]

Steve’s right. The last one of these I did was a 6, which is similar but different and in some ways easier to take apart but harder to get back together.

You probably don’t need a compressor, but you do need the usual cut-off modified broomhandle or slotted bit of PVC or aluminium pipe to relieve the pressure on the pins. I thought every airgun enthusiast had one!

A good set of pin punches are very helpful.

There is an angled screw in the grip frame that can be a sod to get to without a selection of different drivers, or an angled driver. It is very bodgeable, but the right tool is a nice thing.

[Steve Zodiac]

I think I've fixed it.

Well its working anyway.

I released the adjustment lock screw and turned the sleeve adjuster one full turn, I think this increased the sear drop over the trigger do dar.

Anyways, a quick three out of the frame with no grips and it worked ok.

Put it back together and shot a ten string in the cellar, all in the black.

Happy.

Ran it over the skan with Hobbies .22 /11.9gr

1, 385 fps 3.92 ft lb
2, 381. 3.84
3, 367. 3.54
4, 378. 3 74
5, 367. 3.57

Not sure how these figures rate for a model 5G ?

The question is what caused the fault ? I'm thinking possible the trigger release was set way too light as almost a hair trigger when it was resealed by the previous owner.

Would a very small adjustment like that cause such a problem ?

I'll put some more through this week and make sure its not just a short term fluke fix.

Thank you all for your assistance..

[Geezer]

I’m sure you have identified and solved the trigger problem.

The velocity and power figures are where they should be. The 5 and 5G should always make 3 ft-lbs minimum and will occasionally nudge close to 4, but shoot mostly in the mid-3s. The significant spread may settle down with more use.