If its a .308 its a short action.
Short action
Your winchester model 70 chambered in .308 Win.is a short action.
If the rifle is chambered for the .308 Winchester cartridge, then long or short action can safely fire it. Long or short refers to how far the bolt travels when opened. The .308 is typically a short action- the 30-06 and longer cartridges cannot cycle thru a short action, and must be used in a long action rifle.
Short action. Based on the .308 Winchester
It would be considered a "short" action.
The long action simply has a longer receiver, to accommodate longer cartridges such as the .270 or .30-06. The .308 should be a short action. I have seen long action .308 rifles before, but these were typically .30-06 rifles rebarreled for the shorter .308 cartridge.
Long action. .308 and shorter- short action. 30-06 and longer, long action.
Long action will handle longer cartridges, such as 30-06. Short action handles shorter cartridges, such as .308.
Short. Compare cartridge overall length to a .308 Winchester. That is a short action. Longer than that is a long action.
Long action. The .270 cartridge was based on the 30-06, a long action. .308 length is short action.
30-06 and longer cartridges are long action. .308 is short action.