@Fire652 the above advice is all correct, you can't get a 1-6 scope in a VX 3, the 3 stands for 3 times, such as 3-9, the round to 1.5-5. Max magnification is actually 4.5x. There is also a 1.75 to 6, with max magnification at 5.5x.
If you want a great quality but small light weight 1" tube scope for a good price, do find a Leopold VX3 is the 1.5-5, 1.75-6, 0r 2.5-8 version... However if you want a fantastic scope for the money, get a 30mm tube VX6 in 1-6 or 2-12x42. And if you go this route, seriously consider spending the extra $100 or so to get the lighted reticle.
IMO, another great option for a 375 is a VXR in 2-7, priced like a VX3 but with 30mm tube and lighted reticle.
I have a few of each of the above, all great scopes. That 375 Ruger will reach out to 300 yards pretty well with Hornady Superformance 250 grain GMX bullets, or a similar handload.