Which scope rings?

[tcoz]

I've been searching for the answer to this but can't seem to find one that makes sense to me.
I'm a novice when it comes to scopes and I have a question as to what height Vortex Viper rings I need for two rifles. The Viper rings come in low height - .78" base to center, medium - .88" base to center and high - 1.03" base to center.

The two rifles and scopes are:
1. DDM4v11 in 5.56, scope considered is Vortex Diamondback 2-7x35

2. Ruger American .308, scope considered is Vortex Diamondback 3-9x40 or 4-12x40.

It's somewhat possible that I would go with another brand of scopes so in that case would the ring height be the same, only being dependent on the objective lens diameter?
Last question, how practical would it be to buy one scope and switch it back and forth between rifles. I'm thinking this might not be advisable because it would have to be re-zeroed each time and also because ring height might be different which would kill any consideration of doing that.

As always, thanks in advance for your advice.

 

[badkarmamib]

USUALLY, with those objective sizes, medium rings will work best for traditional rifles. In some cases, low will work. AR's need a higher mount, due to the buffer tube being on the same level as the receiver. PEPR-style mounts work well for these.

 

[lobo9er]

I use lowest possible. I have Low rings on all of my rifles... I think anyways. When in doubt I buy low and med. and return the one that won't be used. Warne is now my go to rings. cost/quality is hard to beat.

 

[Tract Optics]

For that Daniel Defense, you'll want to get the optical center up to the 1.375-1.5" mark, depending on your setup and preferences. AR optical height is usually at or around 1.5" due to the design. For that M4, the Burris PEPR is a great mount that doesn't break the bank, but Vortex does have some extra high rings that will get you there as well if you're staying within the brand.

For that American, you can almost certainly go with the low height ring with either of those two scopes.