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Tuning Diana 460 Magnum broke, again!

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bltefft

bltefft

Member
Jan 25, 2017
902
13
West Central Georgia (Columbus, by Ft. Benning), U
Earlier I posted a "Help" post because my Diana 460 Magnum sheared boff the pin the connects the cocking linkage to the bolt. It was suggested that I contact Unarex and I did, Four days later replacement pins and their e-clips arrived. Today, I installed them and thought I was good to go.

I had taken the scope off so I put it back on and started shooting. On the third shoot IT DID IT AGAIN!. That really hacked me off, only when I ook the stock off, it wasn't the pin that had sheared again, no sir, it was the part on the bolt that the pin goes through.

Made me want to chunk the whole thing in the river. I sure liked the power that gun had, I went looking online for another, but when I read others complaining of sheared pins, it turned me off. Now, I'm kind'a scary to buy another. What are you experiences with the 460 Magnum air rifle?

Here are some pictures of my broken 460

Below is the nail is sticking through where the pin sheared off originally

Screen Shot 2021-01-29 at 8.27.39 PM.1611970120.png


Below it the pin back in where it is supposed to be. The nail is gone

Screen Shot 3 at 8.10.37 PM.1611970566.png


Below is the broken part on the bolt. When you cock the gun, the pin pushes against that broken piece and shoves the bolt back and ends with cocking the trigger and putting the safety on. You can clearly see the part on the bolt that is broken - the rear half is gone.

Screen Shot 1 at 8.09.57 PM.1611970670.png
.

So, what are some other springers that rival the 460 Magnum in power and accuracy? I already have a Diana Model 48, an Air Arms TX200, and have bought a Weihrauch HW97K from Krale and am awaiting its arrival - but I'm sure gonna miss that 460 Mag.
 
Wonder if lack of lubrication contributed to extra binding forces on the cocking mechanisms ?
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Looks like rough handling in that rifles past. Never seen anything like that happen with one.
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The above seems likely. I've never heard of other such problems and mine has worked very well. Recently discovered that it will shoot the 12.5 grain NSA slugs very well out to 65 yards.
 
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Totally up to you if you just too lazy to call them that's fine...
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I'm glad it's fine with you. I don't work on air rifles and wouldn't know where to start to replace the action with a new one.
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It's surprisingly easy. Just grab a screwdriver and some bits and take pictures as you go along. You've got to do it to do it!
 
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While my gun is the K98 "Mauser" (springer, not the PCP model), it seems to share the 'action' with the 460 Magnum: I had the same failure in less that 100 shots from a brand new gun (!). The piece that broke (I believe it's called the "hinge pin") seems WAY to small/thin to handle the cocking forces in these guns (maybe it would be OK in a 7.5J version?), plus the fact it appears to be made of "pot metal", or, of sintered or MIM construction).

Not even sure it's worth it trying to get the gun repaired as with such poor design/construction I would guess a real short life. 

And no, I'm not a 'hard cocker" that yanks the cocking arm hard or slams into the stop at the end. I've owned various spring airguns (barrel cockers, sidelevers, and underlevers) since purchasing my first one (from Robert Law's ARH) back in '71, and have never had a problem like this with any of them. A 60+ year-old Diana 35M rifle I have is still running fine on all the original parts, but it seems to me that Diana has "taken the Gold" in contention for top place in makers of 'piece of dung' airguns with the 460 and K98 models.

Broken K98-2.1613848812.JPG

 
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This failure is not likely caused by hard cocking but the piston at the end of its cycle. Especially since both the pin and the lug have broken in a similar failure mode. Have you had it open? A piston seal that has been damaged or does not fit well will come to a harder stop which drives against this portion of the mechanism. Another possibility is a pellet that has become lodged between the front of the compression tube and the barrel housing. This does not allow the spring to run to its normal resting position. I would love to see inside the barrel housing and even better the seals.

Just 2 cents
 
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As for my gun (the K98 "Mauser" with broken hinge pin); I have not had it apart (new gun-didn't want to void the warranty), but had not noticed anything out of the ordinary prior to the shot (after which the gun wouldn't cock). I assume the seals were OK as chrono tests just prior to breakage seemed fine (in the 1050 fps range w/ 8 gr pellets). At that last shot (before it broke), a pellet exited the barrel, so there was no pellet left in the barrel housing (with the hinge pin broken, I can't 'open the action' with the cocking arm enough to see in there right now).

I did get to wondering about one other thing though: Before the gun broke, there were only 2 things I didn't like about the K98. The first is not a factor here; that being what appears to be plastic trigger guard and the forearm band with the carry strap slot also appearing to be plastic.

The second is the lack of a good/positive latch for the cocking arm/under-lever. As one can see from a photo of the gun, there is no latch at the end like found on either of my under-lever guns (HW77K and Gamo Stutzen). I soon discovered it doesn't take much effort to dislodge the arm (there is only a quite small spring-loaded piece [within the front stock-band] that bears on the side of the rod to hold it in place). I found [first time firing the new gun] several times AFTER a shot was fired (esp. if fore-end was resting on a bag) the cocking arm had dislodged. [The OP is about a 460 Magnum, not the K98: does that model have a more positive latch for the lever?].

Anyway, I was wondering if the lever dislodged right at the initial spring surge (moment the piston is released), could it drop down far enough before the end of the piston stroke to move the compression cylinder rearward, with resultant unpleasant collision that would seemingly stress that hinge pin a lot (not too different than pulling the trigger on a barrel-cocker w/o the barrel fully latched up)? Somehow, my suspicion is that could not happen in the milliseconds it takes for the forward piston stroke, but I'm not sure. That 'last shot' did for sure have the cocking lever all the way up when I pulled the trigger as the shot was taken off-hand; where I hold far out onto the stock and would have noticed if the lever was down.

But, I still feel that hinge pin is not up to the task of holding all that applied force when cocking the gun (at least for the high-power versions with stiff springs). My current feeling is that the K98 would be a much better gun "de-tuned" to around, say, 700 fps (in 0.177 cal); "Magnum" power is not really needed in a gun of that type (yeah, I'd already ordered a Vortek 12 ft/# kit for it just before it broke...). And still make that hinge pin a beefier part out of decent metal!
 
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Hello 👋, so I do not have a 460, but your not the first person with this issue. I have seen this a couple times reading the forums, and it seems to be a common issue. I would say give them a call as it’s not the first time this has happened, and if they do fix it for you I’d say sell it. If you want a under lever you can’t go wrong with a Air Arms or a HW. I personally have a TX200 that makes good power 15ft lbs and it’s got 20,000 pellets through it. Or if you want magnum spring power I have a 350 n-tech I give you a deal on.
 
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