The caliber designation of 7mm-08 is considered a short action.
Long
The 7mm Remington Mag.cartridge is a long action cartridge.Its overall length is longer than 2.800in. Also a standard 7mm is long.
A Remington Model 700 chambered for the 7mm 08 cartridge would be a short action as the cartridge is based on the .308 Win.
.308, and its derivative cartridges (like .243 and 7mm-08) and generally short actions. 30-06 at its derivatives (like 270, 25-06) are long actions.
The start of long action cartridges is the 30-06. The 7mm Mag is longer than 30-06, so would it be considered long action.
Ruger American Rifle short action calibers (.243 Win, .308 Win, 7mm .08 Rem, 22-250)
long action: 270, 30-06, 7mm rem mag. Short action: 243, 308, 7-08, 7mm wsm.
10 has short action, 110 has long action. Differerence is about 1 /4 inch in the length of the Receivers. Short action calibers include .223 up to .308, Long action calibers include 270, 30-06 and magnum calibers 7MM and up to 458 Magnum.
Long
Short. Compare cartridge overall length to a .308 Winchester. That is a short action. Longer than that is a long action.
Long action. .308 and shorter- short action. 30-06 and longer, long action.