Tuning Something strange with Diana 48

[Fixedflinger]

So I was shooting a Diana 48 (had the gun since 2010) and on one relaod cycle I noticed it felt funny when pulling the side lever near the end of the travel. Then as I loaded a pellet I noticed the anti bear trap lever was sticking up higher than normal. Then as I whent to close the side lever it was tight, I couldn't get it to move until I disengaged the safety, the the lever closed slightly and stuck again, then I returned to safe position and the lever closed the rest of the way but felt like it had tension on it.
It fired the pellet just fine and then after that everything works normal again.
I can't see anything obvious that would have caused it but I didn't tear it down very far, I'd rather not make it worse by trying to fix it plus it hasn't happened again. Still I'm just afraid that my gun is about to break and I just wanted to see if anyone has experienced something similar or may know what's happening inside my gun.

 

[JamesD.]

Funny thing this just happened to me with my 1988 TO1 48 .177.
I texted John Thomas, AKA John in PA the tuner. He answered right back. Stated it sounds like a rear stock screw. Take it out, file 2 threads off. He was right. I have a ton of files so this was a piece of cake. Just back it out a turn. If you don’t feel that hesitation on end of cocking stroke, that’s the problem.
I simply and neatly filled it down until I saw no burr. Put it back tight, all fixed. I really need to refinish this stock, it’s been my go to hunter for a long long time

 

[JamesD.]

Ya know it also sounds like you might have dropped a pellet down the bear trap slot. I read it closer and could be. Could be both. At least you know what to look for.

 

[Fixedflinger]

Funny thing this just happened to me with my 1988 TO1 48 .177.
I texted John Thomas, AKA John in PA the tuner. He answered right back. Stated it sounds like a rear stock screw. Take it out, file 2 threads off. He was right. I have a ton of files so this was a piece of cake. Just back it out a turn. If you don’t feel that hesitation on end of cocking stroke, that’s the problem.
I simply and neatly filled it down until I saw no burr. Put it back tight, all fixed. I really need to refinish this stock, it’s been my go to hunter for a long long time
View attachment 289524

That would be great if that's all it is, thank you so much. I'm going to check it out now.

 

[Fixedflinger]

I took a really close look at the safety mechanism and I found the culprit!

A small chunk of O-ring caught down inside, my worst fear has been confirmed. It looks like I'm going to be building a spring compressor today

Edit: hold that spring compressor thought, this O-ring may have come from the trigger frame mounting point.

 

[JamesD.]

So how’s it shooting now? I suspect torn O-ring was the culprit but I don’t know where that came from off trigger pack.

 

[Fixedflinger]

So how’s it shooting now? I suspect torn O-ring was the culprit but I don’t know where that came from off trigger pack.

The O-ring was on the ft. trigger guard screw which is also the screw that hold the gun body to the stock. It sandwiches between the stock and
"piston chamber" but it does not appear to actually seal anything but it's more like a bushing or cushion for that mounting point. I found some more small chunks and it seems that when the problem occurred a piece had caught in the piston catch/sear holding the piston back further than normal, which held the sliding chamber back enough to let the bear trap lever ride "higher" up the last ramp/tooth. I think some chunks were caught in the sliding chamber slots that made it catch when trying to move back forward and that's why I had to work the safety in and out to let the arm slide back.

I tried a fuel injector O-ring, but it was way too thick, then I found an AC line O-ring that worked just right. I was almost about to the point of just cutting out a piece of inner tube, but the AC ring worked perfect. The shot cycle feels normal, but the scope is now having problems so I can't tell for sure if my groups have opened up because I can't trust my optics anymore. Major POI changes after parallax adjustments, and focus changes after 3-4 shots.