The Vortex Diamondback Tactical 3-9x40 Rifle Scope features the Vortex XR Fully Multi-Coated lens and Vortex XD HD lens elements to provide excellent clarity and light transmission. Its clarity is similar to the Crossfire II as they use the same lens coating elements.
The Vortex Diamondback Tactical 3-9x40 Rifle Scope is 12.5" long.
This is a great all around beginner scope and would do fairly well in low light conditions, but Leupold uses arguably some of the best technology to get the most out of low light situations so it really depends on what scope you are trying to compare the Diamondback Tactical too.
Yes, this riflescope will have no issues on a slug gun of any caliber, but please be very aware of the eye relief which is set at 3.9" to avoid any harm to the shooters eye when firing the gun.
This scope will have no issues on a rifle chambered in .325 Winchester Short Magnum.
The turrets cannot be locked, but they can be reindexed for your zero so that if turrets accidentally get moved from your zero you can just set them back.
Yes, this scope will have no issues on a slug gun as long as you have the appropriate mounts for whatever your firearm is.
Yes and you can find a sunshade here:
https://www.opticsplanet.com/vortex-diamondback-tactical-riflescope-sunshade.html
Because of the 40mm objective the mediums should likely be a fine height, but please be aware that all manufacturers have slightly different heights that they label as low/medium/high, so one companies low may be another companies medium and so on.
Yes, these rifle scopes can be used on just about any caliber rifle. Here is the reticle manual:
https://vortexoptics.com/media/uploads/web_manual_reticle_dtac-vmr-1-moa.pdf