Locking bolt meets the bolt

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dalek
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Locking bolt meets the bolt

Post by dalek »

Correct me if I am wrong but the cutout on the sides of the bolt is such that the curved bottom pushes the bolt forward as the licking bolts start to rise and then go straight/vertical in the bolt locking phase. If that is the case, let's say the locking bolts stop at around 1cm from the top, which also means the lever is not all the way up, but the bolt seems to have nowhere forward left to go. Without going through jokes about ROssi's workmanship (not their fault here; I am really trying to understand how the "fitting" process works. In fact, let's just say bolt and locking bolts never met that rifle before), what is this telling me?
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Re: Locking bolt meets the bolt

Post by GasGuzzler »

Did you take it apart?
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Re: Locking bolt meets the bolt

Post by zippy »

dalek wrote:... let's say the locking bolts stop at around 1cm from the top, .... but the bolt seems to have nowhere forward left to go.
I just pulled my 92 out to watch it's bolt while I worked the lever.
The first bit of movement of the lever off of full lock-up drops the locking lugs to the 1cm low position you describe, without releasing tension on the bolt.

I'm not sure where your going with your question, but at the locking position you describe, the bolt is fully forward. The additional upward travel of the locks requires no further forward travel of the bolt. The cam action is complete at that point.
Good luck.

Lower limit of lugs at bolt forward position.

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Re: Locking bolt meets the bolt

Post by nvbirdman »

Are we talking empty gun or round in the chamber? If it only happens with a round in the chamber it is a headspace problem.
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Re: Locking bolt meets the bolt

Post by dalek »

zippy, your description matches what I observed (and try to describe in the original post) by staring at the bolt cutout shape and playing with the assembly. So, if I am not mistaken, the two phases are:

1. Locking bolts move up riding the curved cutout on the bolt, moving it forward until it reaches the locked position. This phase, closing up the bolt, stops when locking bolts are about 1cm from their full travel position. If you can imagine a non-straight pull bolt action rifle, this is the part when you shove the bolt all the way forward.
M92_26-sm.jpg
M92_28-sm.jpg
2. Locking bolts keep on sliding up, now in the bolt straight channel. I take this is when you lock the bolt in place; using my bolt action analogy, you now rotate the bolt to its locked position.

To the others who replied to the thread, which I appreciate, let's assume for the sake of argument nothing is broken. Instead I am trying to understand how the lever action in, well, a lever action firearm works.

nvbirdman, since you talked about headspacing, and my headspacing thread (http://rossi-rifleman.com/viewtopic.php?f=44&t=4869) remains unloved, we will hijack this one. How are these rifles headspaced at factory? I know people here have headspaced using the barrel, but I wonder if at the factory it would be easier to either have a pile of locking bolts of different thickness or an oversized one and then grind it to fit. Since I am in an analogy mood today, that is how the SKS, the FN49, the G43, the MAS49, the SVT-40, and the FN FAL are headspaced. And it is quick to do if you have the locking lugs on hand and you do not need to have to worry about front sight alignment.

If what I said above is true, if the rifle would only fully close in an empty chamber -- I am using here your example -- it would mean either the bolt would need to travel forward, which might be hard if the front surface of the locking bolt cutout is flush with that of the receiver. You would need some kind of locking bolt with a stepped front surface that would be ground to fit. Or, play with the barrel.

Of course all of the above are ASSumptions of mine which might have no bearing with reality. :lol:
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Re: Locking bolt meets the bolt

Post by zippy »

dalek wrote:zippy, your description matches what I observed (and try to describe in the original post) by staring at the bolt cutout shape and playing with the assembly. So, if I am not mistaken, the two phases are:

1. Locking bolts move up riding the curved cutout on the bolt, moving it forward until it reaches the locked position. This phase, closing up the bolt, stops when locking bolts are about 1cm from their full travel position. If you can imagine a non-straight pull bolt action rifle, this is the part when you shove the bolt all the way forward.
I'm not knowledgeable on the inner workings, but your description in step 1. is what I observed.

Something seems a bit odd to me with the picture you posted of the top of the bolt. The edges of the two halves of the mortise that the locking lugs ride through seem to align, indicating the bolt is fully forward. But the back of the bolt is still protruding out the back of the action. The back of my bolt is flush to the rifle when the mortise edges align.
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Re: Locking bolt meets the bolt

Post by GasGuzzler »

Generally these questions are asked when something doesn't work properly. Now I know different I'd rather have not replied in the first place.
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dalek
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Re: Locking bolt meets the bolt

Post by dalek »

zippy wrote:Something seems a bit odd to me with the picture you posted of the top of the bolt. The edges of the two halves of the mortise that the locking lugs ride through seem to align, indicating the bolt is fully forward. But the back of the bolt is still protruding out the back of the action. The back of my bolt is flush to the rifle when the mortise edges align.
Right you are, and you might have also noticed the bolt is a bit taller than the receiver. The reason is that bolt (and locking bolts for that matter) are not the ones that came with that Rossi 92, but they are supposedly from a Puma. Why they are together? I had to know how compatible they were; I am one of those guys. :shock:

And that led to me wanting to understand how the lever action system in the 92 works (which is a bit different than the one in a Winchester 1895). My mind wanders like that. After I understand how the locking bolts are adjusted for headspacing (assuming my previous comments hold true), next would be the relationship between the lever travel, the curvy parts in the bolt, effort, and speed. It sounds like a geometry problem just like in a revolver.
GasGuzzler wrote:Generally these questions are asked when something doesn't work properly. Now I know different I'd rather have not replied in the first place.
I cannot vouch for others, but when I ask a question I genuinely want to know the answer. Sometimes it is to repair something, other times to understand how it works. For instance, in another site I asked about how the mechanism to rotate a revolver cylinder worked including the geometry. Nothing was broken but until then I've always felt revolvers involved witchcraft.

I did not mean to make you regret posting a reply, to which I apologize. :oops:
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Re: Locking bolt meets the bolt

Post by GasGuzzler »

My point is my reply was meaningless. Now I have three herein. HA!
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Re: Locking bolt meets the bolt

Post by dalek »

So here is an update: Locking lugs now fit tight (no freeplay) and yet seem to go as far up as they should:
M92_29-sm.jpg
M92_30-sm.jpg
M92_31-sm.jpg
What I did find out was the large surface are in the cutouts -- the part that rubbed against the sides of the locking lugs -- was crowned like a road. I flattened that and then trimmed the front and rear of the lugs until they would just fit inside the holes. I did not bother to trim each lug to match the other since (a) the holes were different in size just enough and (b) they kind of free float a bit since the screw they, and the lever, ride on has a lot of freeplay by design. Besides smoothing the bolt and taking off the crown mentioned above, I did the trimming on my locking lugs because I assume they are easier to make/find.

I still have not slapped all the parts back together but hope everything is lined up. If not, at least I feel now I know how it works. And from this picture,
M92_32-sm.jpg
We can see when locked there is a lot of surface area between the locking lugs and the bolt and receiver. There is a lot of traveling the lugs have to do before bolt is unlocked, which IMHO is a good idea. But, it does make me wonder what wears out when someone says their 92 has excessive headspacing: bolt or locking lugs or receiver?

Now, I have no idea what the grooves on the rear inboard of the lugs are there for. Anyone?
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