Not only do you have rimfire, long, and short but a few more. There's an intermediate length action discontinued some years ago falls between short and long hence the "intermediate". You have a difference between old short action and new short action. You also have the Precision target action which has three screws rather than two, and the dual port which has three screws on a different spacing than the PTA all together.
This unfortunately is what drive stock makers up a wall with savages.
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Opps forgot the muzzle loaders too...
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Savage Centerfire Action Lengths
Savage Centerfire Action Length Identification. To help determine what action you have, here are the action screw center-to-center measurements.
Long Action: 5.062" (all years)
3rd Gen Short: 4.400" (2006 - present)
2nd Gen. Short: 4.275" (1998 - 2005)
1st Gen. Short: 4.522" (1959 - 1988)
Striker:
Additional Notes:
- The 1st Generation Short-Actions are today commonly referred to as "J-Series". This is incorrect as a "Series" designation simply refers to a slight design change. Rifles marked "Series J" can be either a 1st Gen. short-action or a long-action.
- The 2nd. Generation Short-Actions comprise most of what you will run across.
- The 3rd Generation Short-Actions are the newest production models and can be easily identified as they will have the new center-feed magazine system. The only exception is rifles originally built in .223 Remington or .204 Ruger as Savage has yet to release a center-feed magazine for these smaller diameter cartridges. <-- as of april 2008