well , if you have a small shank then you'll need a small shank lug , but if its a big shankl action and barrel then your gonna need a large shank lug:p
Realy , the OD on the threads of the barrel should be 1.062"x20TPI for the small shank but generaly for factory barrels they can be as loose as 1.055" OD
while the Large shank Savage barrels threads are 1.120"x20TPI , agaijhne the factroy barrels can vary as much as .005" from barrel to barrel.
If your talking about the action you got from me then you will need a small shank recoil lug ,the ones from Sharp shooters supply are great as they have the screw stud already centered in the lug so it won't spinn when you tighen the barrel.
Small shank barrels are the most common. The large shank come on the target actions, and later RUM, and WSM chamberings. The barrel diameter for a small shank barrel is 1.055. I large shank is around 1.120. If your barrel is a factory take off 7mm remington mag then a standard shank is what you need. $28 for a SS machined lug at Sharpshootersupply.com
Buyer beware with Sharp Shooters. I hear that the product is good, but I can attest that the customer service is VERY substandard. After I had a terrible experience, I did a little research, and found that there were others that had similar problems.
There were others, but this one is pretty representative.
Bullets have well documented performance specifications.
Min Velocity info is available, and describes the performance floor of the bullet... DON'T allow yourself to reference F.P.E. as an accurate descriptor of killing power.. You are smarter than a copy editor, and you understand that you can determine maximum (reliable) effective range by comparing your drop chart to published bullet data....... And, dog-on-it, people like you!