If this gun is a military M10, then the slot that is visible in the lower left quadrant of the bolt face should be on the lower right. It's the groove the ejector slides through to eject the spent casing. Somehow the bolt head has rotated into "locked/in battery" position while in the action. Other evidence demonstrating the fact that it's in battery position is that the firing pin is protruding. I have no idea how this has happened....... though... directly in front of where the bolt head is there should be a spring loaded triangular shaped flat ejector that slides in and out of a notch in the receiver in line with the left rail - left side of the action if viewed from the back. It looks like that's missing on this gun, or possibly jammed back in the receiver with rust, old grease or dirt. I don't have a ross in front of me at the moment, but in theory that ejector being absent might allow the bolt head to rotate?
Disclaimer - There are a very few commercial sporting rosses that orient their lugs vertically when being cycled, but this doesn't look like one of them. I'm not familiar enough to say definitively, but it doesn't look like any I've seen with the vertical lug configuration.
Anyways, some possible solutions:
1) strip down the gun - action out of stock, trigger group and mag off the gun, rear sight off - this'll give you full unobstructed view of what's happening. Post pictures so we can see properly.
- To remove the rear sight bridge (all the metal above the action that the rear sight is mounted on can be removed as one piece) unscrew the two screws on the top left of the bridge that're in line with the long axis of the gun and flush with the metal surface, and the two screws on the right of the bridge low down, or possibly below the wood line of the stock.
2) If the bolt head did slip, you might be able to rotate it back the way it came. I use the word might because some dicknugget may have slammed it in there and using that kind of force may damage things. If it can be rotated, the ross bolt pulls forward and rotates at the same time. It's usually pretty stiff, so might be difficult with any additional resistance.
3) removing all the additional parts (mag, trigger group and rear sight especially) might help remove the bolt.... at least it'll be less stuff to hang up on and get in your way.
Finally - Make sure to check the bolt and action over when you finally remove it. Something's wrong with the gun somehow... since ross bolts can be disassembled wrong, it's possible that it might be on this rifle, especially considering whoever last owned it doesn't seem to have been especially technologically gifted.
And since I'm typing, My 2C..... I have no idea how or why, but it seems like rosses attract absolute idiots
I'm not referring to you OP, I'm referring to the faceless individuals that manage to blow their rosses up, shear bolt lugs, jam their actions and otherwise demolish them. I collect M10's and have never had a problem with them, yet somehow every fudd and his girlfriend/sister has been involved in a ross blowing up or otherwise malfunctioning.
Oh, and here's what happens when you assemble the bolt wrong:
