Diana 350 cocking arm dragging/galling

[Ike the GSD]

Does anyone know what could be causing this and what to do to fix it? I know when the action is out of the stock you have to hold down the arm that goes into the piston slot or it will raise upward and bind? Does the stock play a part in keeping the cocking arms in the correct position, I saw some wood scuffed up in the channel just before the opening.

[Roadworthy]

Typically with an articulated (two piece) cocking arm the stock holds the "knee" in place during the cocking stroke.  If you find it gouging the stock you could try to inlay a thin piece of nylon into the groove in the stock.

[Ike the GSD]

Typically with an articulated (two piece) cocking arm the stock holds the "knee" in place during the cocking stroke.  If you find it gouging the stock you could try to inlay a thin piece of nylon into the groove in the stock.

Thanks Tom, I'll give that a try, it shouldn't take much. I lightly filed and sanded the groove in the compression tube and that helped some, there weren't any burrs, but the slot was very rough.👍

[mikeyb]

I have a Ruger Air Magnum which I believe is a close sibling to the BAM28 or XS28.

https://xisicousa.com/PartsDiagram/XS28Mdiagramlist.pdf

... which is supposedly a copy of the Diana350.

I have NOT taken mine apart yet. OTHER similar rifles I HAVE disassembled use a 2-part cocking link that has a form of roller bearing/wheel in the cocking link which rolls smoothly against the outside of the compression tube guided by a slot in the stock. My stock is plastic so naturally more slippery than wood. Plastic lining a wood slot could help but I think the problem will still exist.

If the roller is not "rolling" (lack of lubrication, roller missing?) steel rubbing on steel here would not be good IMO and galling seems likely.

Sorry, drawing linked above is not good enough to see roller detail.

[Ike the GSD]

I have a Ruger Air Magnum which I believe is a close sibling to the BAM28 or XS28.

https://xisicousa.com/PartsDiagram/XS28Mdiagramlist.pdf

... which is supposedly a copy of the Diana350.

I have NOT taken mine apart yet. OTHER similar rifles I HAVE disassembled use a 2-part cocking link that has a form of roller bearing/wheel in the cocking link which rolls smoothly against the outside of the compression tube guided by a slot in the stock. My stock is plastic so naturally more slippery than wood. Plastic lining a wood slot could help but I think the problem will still exist.

If the roller is not "rolling" (lack of lubrication, roller missing?) steel rubbing on steel here would not be good IMO and galling seems likely.

Sorry, drawing linked above is not good enough to see roller detail.

Thanks Mike, the 350 doesn't have a roller bearing attachment (it should) but there's no room for one to fit, I've looked at complete replacement units and they look just like mine. I'm just going to take a milk jug and cut a piece to lay in the channel. The more I work on this rifle the more the foibles I find. I just hope the new parts will put it back to normal, I ordered a new factory mainspring from Chambers and Diana is sending a new piston so in a week or two I'll know if the rifle is salvagable.

[Ike the GSD]

Well I had to cancel the mainspring order from Chambers because the spring I ordered is a UK compliant version and the only other full power spring they offer is the Titan #14 and after reading a few posts on the #14 I'm not sure if it would work very well?  Vortek doesn't offer an OEM spring for the 350 anymore and the ARH springs are shorter than the factory mainsprings. Blueline won't sell parts to individuals, just dealers,  I can't believe this is becoming so difficult😬

[Toxylon]

My understanding is that the many reported ill-fitting Titan #14's in 350 Mags is the result of not having sufficiently tight custom guides for the massive-ID / OD spring, leading to spring noise & friction etc.

Titan #14 is also so large that you need to take both the OEM piston sleeve and the OEM piston weight out for it to fit.

[Ike the GSD]

My understanding is that the many reported ill-fitting Titan #14's in 350 Mags is the result of not having sufficiently tight custom guides for the massive-ID / OD spring, leading to spring noise & friction etc.

Titan #14 is also so large that you need to take both the OEM piston sleeve and the OEM piston weight out for it to fit.

I remember you saying that once in another thread, why would Titan make a spring this way? It's not appropriate for this rifle. They must not test their products in the rifles they sell their springs for? The wire diameter isn't even correct at .141 vs .128 I just don't understand why a factory spring is so difficult to obtain, the rifle is still in current production?

[Toxylon]

There are no Titan springs that were made for a single airgun model. The Titan #14 is a replacement spring for the Webley Patriot and the 350 Mag.

As you may know, the Patriot is a much bigger cylinder gun with a larger swept volume than the 350 Mag. It's also a British gun, so I have no problem assuming the #14 was designed for the Patriot first and foremost.

The Titan #14 does fit the 350 Mag as per length and OD, barely. People who have used it in theirs report MV and ME in the OEM ballpark, so it fits per output, as well.

[Ike the GSD]

There are no Titan springs that were made for a single airgun model. The Titan #14 is a replacement spring for the Webley Patriot and the 350 Mag.

As you may know, the Patriot is a much bigger cylinder gun with a larger swept volume than the 350 Mag. It's also a British gun, so I have no problem assuming the #14 was designed for the Patriot first and foremost.

The Titan #14 does fit the 350 Mag as per length and OD, barely. People who have used it in theirs report MV and ME in the OEM ballpark, so it fits per output, as well.

I'd LOVE to own a Webley Patriot❤😜👍

[mpbby]

I would contact Vortek about the 350 spring..  If they may sell it for you, I would buy 2 or 3, just in case..

About the cocking arm.., never, ever, try to pull the barrel when the action is out of the stock.. This will damage the spring sleeve.

[Ike the GSD]

I would contact Vortek about the 350 spring..  If they may sell it for you, I would buy 2 or 3, just in case..

About the cocking arm.., never, ever, try to pull the barrel when the action is out of the stock.. This will damage the spring sleeve.

Thanks Marcos, yeah I saw right away the arms will bind if you don't support the bottom arm, I added some plastic shims to the channel in the stock but it didn't help much if at all.

[tjk]

Unlike the Bam/Xisico Chinese clones that incorporate a two piece articulating cocking arm, the German made Diana 350 uses a single cocking arm that has no contact with the stock. The problem is that the cocking slot and the round end of the cocking arm need to be smoothed and/or deburred. You may not think there are burrs in there, but if it is rough, you probably do have burrs you can’t see or feel. A good test is to use a cotton swab and pull it along the filed and polished edges, if a fiber gets snagged, then you’re not finished deburring and polishing it.

[Roadworthy]

My bad - tjk is correct, the 350 does use a one piece cocking arm, unlike its Chinese "cousins".  You may have some wobble during the cocking stroke causing the angle of applied force to change minimally.  This could accelerate gouging and wear.  I'm sorry for my confusion.

[Ike the GSD]

My bad - tjk is correct, the 350 does use a one piece cocking arm, unlike its Chinese "cousins".  You may have some wobble during the cocking stroke causing the angle of applied force to change minimally.  This could accelerate gouging and wear.  I'm sorry for my confusion.

No Tom you were absolutely correct, the 350 uses a two piece cocking arm.

https://twchambers.co.uk/airgun-spares/diana-original/350-magnum-to1/350-magnum-to1-cocking-lever-for-to5-to6-models-only-ul203-1/

[Toxylon]

Yeah, my 2015 D350 has a two-part cocking arm just like my Xisico clone barrel had, and it wouldn't work any other way. The D34 has a single-piece cocking arm, which makes dismantling the 350's smaller, older brother a special kind of chore.

[Ike the GSD]

Yeah, my 2015 D350 has a two-part cocking arm just like my Xisico clone barrel had, and it wouldn't work any other way. The D34 has a single-piece cocking arm, which makes dismantling the 350's smaller, older brother a special kind of chore.

I'm learning to hate this rifle more every day, I can't even get a factory mainspring for it, it's as if the rifle has been long discontinued😬🤷‍♂️

[ER00z]

Yeah, my 2015 D350 has a two-part cocking arm just like my Xisico clone barrel had, and it wouldn't work any other way. The D34 has a single-piece cocking arm, which makes dismantling the 350's smaller, older brother a special kind of chore.

I'm learning to hate this rifle more every day, I can't even get a factory mainspring for it, it's as if the rifle has been long discontinued😬🤷‍♂️

Vortek can sort you out with a drop in OEM equivalent spring if you want to go that route... If ordering a custom spring from them, I recommend the .128" wire with .825" OD. I forget the coil count needed to be honest. I'd compare coil count to original if available.

You can use a .135" wire .825 OD vortek custom spring with the factory guide, but 35 coils would be a bit too strong. My D350 in .177 was making nearly 23FPE with that spring, I recommend 33 or 32 coils and maybe spacing up if needed if going this route.   

[Ike the GSD]

Yeah, my 2015 D350 has a two-part cocking arm just like my Xisico clone barrel had, and it wouldn't work any other way. The D34 has a single-piece cocking arm, which makes dismantling the 350's smaller, older brother a special kind of chore.

I'm learning to hate this rifle more every day, I can't even get a factory mainspring for it, it's as if the rifle has been long discontinued😬🤷‍♂️

Vortek can sort you out with a drop in OEM equivalent spring if you want to go that route... If ordering a custom spring from them, I recommend the .128" wire with .825" OD. I forget the coil count needed to be honest. I'd compare coil count to original if available.

You can use a .135" wire .825 OD vortek custom spring with the factory guide, but 35 coils would be a bit too strong. My D350 in .177 was making nearly 23FPE with that spring, I recommend 33 or 32 coils and maybe spacing up if needed if going this route.

The original spring has 40 coils I bought a replacement from Tom earlier this year but he's since quit offering them and the kits, the custom spring max length is 36 coils in the .128/.825 configuration. The .135 wire spring would get closer to factory specs, I can cut coils if I have to, if I ordered the 36 coil .128 spring he offers now I'd just have him close the ends and leave it alone.

[ER00z]

Yeah, my 2015 D350 has a two-part cocking arm just like my Xisico clone barrel had, and it wouldn't work any other way. The D34 has a single-piece cocking arm, which makes dismantling the 350's smaller, older brother a special kind of chore.

I'm learning to hate this rifle more every day, I can't even get a factory mainspring for it, it's as if the rifle has been long discontinued😬🤷‍♂️

Vortek can sort you out with a drop in OEM equivalent spring if you want to go that route... If ordering a custom spring from them, I recommend the .128" wire with .825" OD. I forget the coil count needed to be honest. I'd compare coil count to original if available.

You can use a .135" wire .825 OD vortek custom spring with the factory guide, but 35 coils would be a bit too strong. My D350 in .177 was making nearly 23FPE with that spring, I recommend 33 or 32 coils and maybe spacing up if needed if going this route.

The original spring has 40 coils I bought a replacement from Tom earlier this year but he's since quit offering them and the kits, the custom spring max length is 36 coils in the .128/.825 configuration. The .135 wire spring would get closer to factory specs, I can cut coils if I have to, if I ordered the 36 coil .128 spring he offers now I'd just have him close the ends and leave it alone.

I was mistaken about the .135 spring I used... Apparently I ordered a 38 coil spring, which was a bit too strong. Apologies for having a foggy memory. Here's a link to the thread regarding my experience, reply #6 is what I ordered (pg3 kit and also a .135 spring)...

https://www.gatewaytoairguns.org/GTA/index.php?topic=187575.msg156156921#msg156156921