Slight Issue With Wear On Panda Bolt!

D

DSM

Chuck
I started noticing a slight notch at the top of the bolt cycle and it appears this wear indentation on the bolt is causing it. It is caused by the bolt hitting the action when closed. I only have about 350 rounds cycled through this action and kinda irritated by it. I have another Panda that is several years old and has slight wear mark in the same area, but not as bad. Can this be worked out by hand and polished?

bolt2.JPG

bolt1.JPG
 
It is not caused by the bolt hitting when closed, it's because of the bolt hitting the insert for primary extraction. Look at the back of the "rear bridge" above the boltway, you'll see a round steel insert. That is what the bolt is hitting, or actually rubbing on at primary extraction. They all do it to some degree.
 
You've been shooting some hot, sticky loads ;) might consider having your chambers cut to avoid this?

I would dress it up, it looks like dawggg

al
 
I wouldnt think there would be that much wear at 350 rounds fired. Thats nothing really. Now if this were the case at 5000 rounds i wouldnt blink an eye. Looks like soft metal to me. There again, what do i know!!! Hope you get it worked out! Lee
 
Looks to me like the opening/primary extraction cam surface, one the rear bridge, and the surface that it works against on the bolt do not fit in a manner that spreads the load over a wide enough area.
 
Boyd Allen said:
Looks to me like the opening/primary extraction cam surface, one the rear bridge, and the surface that it works against on the bolt do not fit in a manner that spreads the load over a wide enough area.
Click to expand...

Boyd, You are right. Fact is, many don't. Remington is right up there. I asked this question on the gunsmith forum a while ago, and was told that a small contact area was better than a large one, less contact, less drag. While I don't agree with this concept, when you have an action in hand that does not have good mating surfaces, it is a large undertaking to change it all. Some would be a complete re-work, if that's what you want. This is fairly prohibitive once the action is machined.

I think a large area, machined to be as close as possible, is the best design. Doesn't have to be a lapped contact, but that could be achieved too.
 
Have you looked at a Viper? One factor is how many axes the mill has that produced the shape, and the sophistication that went into the design....I think :)
 
That little v notch is not wear, it is a dent caused by slamming the bolt forward on an empty chamber. The points of
contact that come into play here can easily be seen if you operate the bolt slowly and focus where the bolt makes its
first stop.
 
Bob Kingsbury said:
That little v notch is not wear, it is a dent caused by slamming the bolt forward on an empty chamber. The points of
contact that come into play here can easily be seen if you operate the bolt slowly and focus where the bolt makes its
first stop.
Click to expand...

Now that makes sense. I've been aiming to look at mine to see what would make that mark. It just didn't make sense for the extraction cam pin to put it there. But on second thought..maybe it is the pin but happening when the bolt is slammed forward against it, not upon opening. Everything else there is aluminum.--Mike Ezell
 
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Bob Kingsbury said:
That little v notch is not wear, it is a dent caused by slamming the bolt forward on an empty chamber. The points of
contact that come into play here can easily be seen if you operate the bolt slowly and focus where the bolt makes its
first stop.
Click to expand...

I don't believe one could intentionally "slam" a bolt down against the rear bridge enough times and hard enough to peen the root of the bolt like that. Not unless there is some malicious act taking place.
 
I shoot fast if a condition permits and maybe I am inadvertently slamming the bolt. Nothing malicious is going on nor is my loads anywhere near being hot.
 
hmmm, slamming actually makes more sense IMO than sticky rounds. I'll stand corrected. Sticking cases ("the click") will gall the root of the bolt not warp it. I've changed over to the slamming theory :)

al
 
DSM
Just wondering did you buy the action new or used? looks to me like the bolt handle is in the wrong place? look at the flat at the end of the handle in relation to the flat on the bolt shroud, also in the 1st pic looks like some tig welding has been going on?

KB
 
Purchased brand new straight from Kelbly. The bolt handle is tig welded on. I believe that is how they are attaching them now. My older Panda is soldered or brazed on.
 
I looked at mine...on it, it's easy to see how this would happen if you just cycle it and watch where the pin in the action hits the bolt handle. It's right where the mark is on yours. In fact, mine has a slight mark in the same location, just not quite as bad. I don't think it can hurt a thing unless it gets a lot worse.--Mike Ezell
 
DSM said:
I started noticing a slight notch at the top of the bolt cycle and it appears this wear indentation on the bolt is causing it. It is caused by the bolt hitting the action when closed. I only have about 350 rounds cycled through this action and kinda irritated by it. I have another Panda that is several years old and has slight wear mark in the same area, but not as bad. Can this be worked out by hand and polished?

bolt2.JPG

bolt1.JPG
Click to expand...

You should polished that. I think it will work again.
 
The dent only occurs when no case is in the chamber. Having a case in the chamber stops the bolt before it contacts the rear
bridge of the receiver. With no case, the bolt stops at the transition of the flat and extraction cam.
Admiring your new action and cycling the bolt while watching Oprah is how this is done.
 
Is the "notch" felt when opening the bolt on an empty chamber? If not, put some grease on that rough spot, chamber a FL sized (FL is key) round and open the bolt. If the "notch" remains absent, fire the round. If the "notch" appears when opening the bolt after firing, the chamber may be either to rough or too smooth. The already present rough spot should be polished up a bit (very little bit) and when the root cause is determined is prolly won't reappear. Look at everything that might cause higher pressure - case length, neck diameter (loaded round), oversizing, etc...

In any case, if you can't solve this problem rather quickly, contact Kelbly's for a solution. Any distraction in competition is one too many.
 
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