Currently, the mosin with a greased bolt costs one supply point more than the SVD, and the M24 with a greased bolt is the same cost as an M14.
Both of these comparisons don't seem fair at all, the bolt action rifles are unfortunately worse in most respects that matter.
I think two simple balance changes could make the bolt actions have a viable place in sandstorm without (hopefully) significant dev time or effort.
First, the bolt actions and the greased bolt should each have their supply cost reduced by 1, so overall a bolt action + greased bolt will now cost 3 instead of 5 supply.
Second, the Scope FOV for bolt actions should be increased. What I mean is that the area of the screen that is within the scopes' housing should be larger. what is outside the housing (the peripheral vision that is blurred) should be a much smaller portion of the screen. This should apply to 7x and 4x scopes.
To show what I mean, look at the two screenshots below. The one from sandstorm has much less of the screen visible through the scope, while the Insurgency source screenshot shows the scope including a much larger portion of the screen within its housing.
Note: I made the following images on 100 FOV in both games. I do not use duel rendering for scopes in Sandstorm.
Sandstorm Scope View: https://imgur.com/a/b64GIHG
Source Scope View: https://imgur.com/a/XzKLZCM
50/50 transparent overlaid scopes: https://imgur.com/a/auNFfRr
As you can see in the overlay-ed scope graphic, in source it was possible to see much more of the map through a scope. In sandstorm, there is a much smaller view angle through the scopes.
This causes scopes to generally be worse in Sandstorm, but provides us with a way to make bolt actions have a role in the game. If the bolt actions get wider views when using scopes (like what we had in source), they will be able to more easily view multiple pieces of cover at once. When I play sandstorm with a scope I never feel like I can cover an area, I always have to stare at 1 spot through my scope and try to flick to other angles when I see movement in the peripheral vision (which is blurry). By making it easier for bolt actions to cover a wider area of the map with a scope, they move into the role of defensive sniping, especially from powerful positions on the map. This is generally what we want from our snipers. The M14 and SVD will not get this increase in scope view, and so while they will be better in ROF and magazine capacity, they will not be as effective at covering larger portions of the map from a defensive position.
I think this change will give the bolt actions a viable use in the game that differentiates them from the M14 and SVD (which are generally better in most situation). I don't think this change would meaningfully reduce the immersion or realistic feel when using bolt actions either.