Diana Gritty Diana P5 Barrel Lockup

[Bad News Beeman]

Hi guys, was out shooting early with my Diana 5P Magnum pistol and after several shots noticed that the barrel lockup started feeling gritty and required more force to snap the barrel in place. I tried first tightening and then slightly loosening the crossbolt but neither had a discernable impact on the grittiness. Doesn't look like there's any gunk on either the ball detent in the breach block or locking nub.

Only noticeable errors during my shooting session were having overlubed the chamber with silicone beforehand causing slight smoking, and shooting crappy Brazilian-made Crosman domed pellets that are somewhat undersized.

Any idea what's causing these issues with lockup? Could either of the above be contributing factors?

 

[marflow 777]

i would try to clean the bearing ball off with a swab and a little rubbing alcohol and then re-lube it with a little grease

 

[Bear-of-Grayling]

May have blown the piston seal.

 

[bustachip]

If it were me I would take the barrel off and clean everything, washers if there are any. Also I would try and remover the ball or whatever it is, because there's probably a spring behind it, and maybe gunk and metal chips? Then relube assemble and adjust the lock up tension.

 

[Bad News Beeman]

Good advice guys, I will definitely start by taking the barrel off and seeing what's going on. The strange thing is that most of the travel when cocking is smooth, its only when snapping the barrel back into place that the friction becomes super tough.

 

[bustachip]

Maybe take the action out to see if there's something going on with the linkages. I know nothing about these guns or if they have a cocking shoe or not. It's really hard to say without the gun in front of me.

 

[marflow 777]

you would take the bearing ball out really
and then how are you going to re-stake it in place oh it could be done but it would be a last resort and even with my knowledge i could not do it without making some special jig
the cocking lever assembly is the same that has been used for 50+ years on the model 5's and model 6's and i doubt it has much to do with it
without seeing the tube side it is hard to say and the lockup piece on the tube could be damaged
https://www.jgairguns.biz/27-c-78_247_255/dia300281-detent-p-4056.html

 

[bustachip]

you would take the bearing ball out really
and then how are you going to re-stake it in place oh it could be done but it would be a last resort and even with my knowledge i could not do it without making some special jig
the cocking lever assembly is the same that has been used for 50+ years on the model 5's and model 6's and i doubt it has much to do with it
without seeing the tube side it is hard to say and the lockup piece on the tube could be damaged
https://www.jgairguns.biz/27-c-78_247_255/dia300281-detent-p-4056.html

No telling, but if it were in front of me I could fix it.

 

[marflow 777]

the problem is when they stake a spring and ball in the breech it takes a special tool to hold the ball and push it beyond the lip of the breech and what they use to stake it, either pressure or hammer shot is unknown and i would bet it is done before the barrel is installed
now to remove it you are going to have to remove the staking and then R&R the piece and now the areas that were staked are not useable because of material lose
and after that, the once tidy job will look like what, a mess

have him send it to you and have at it i don't really care i have read enough forum on this exact thing it never goes well

 

[bustachip]

the problem is when they stake a spring and ball in the breech it takes a special tool to hold the ball and push it beyond the lip of the breech and what they use to stake it, either pressure or hammer shot is unknown and i would bet it is done before the barrel is installed
now to remove it you are going to have to remove the staking and then R&R the piece and now the areas that were staked are not useable because of material lose
and after that, the once tidy job will look like what, a mess

have him send it to you and have at it i don't really care i have read enough forum on this exact thing it never goes well

Makes sense, like I said I've never seen one, just figured a pin or something holding it back.

 

[Bad News Beeman]

Yea I don't know how one would go about removing and reinstalling either the ball or the detent piece without special tools.

 

[marflow 777]

i have an idea
i have a P5 that i needed to take the barrel off and today was the day
the sear and parts are not the same as a model 5 and 6
there is a very odd torsion spring the linkage pin goes through
and the sear is spring loaded also
now if the spring broke it could do, i have no idea
to put it back together was a learning experience and very hard
so, I live and learn