LEU*MK4 1PCBS 20WIN 70 LA

The Leupold MK4 1-piece base for .20 Winchester and .70 LA actions provides solid receiver mounting for precision optics. Whether you're building a long-range setup in San Ramon or handling an FFL transfer in Sunnyvale, quality bases matter. This one-piece design eliminates the flex that comes from two-ring systems.

One-piece base construction and rigidity

A single-piece base distributes clamping force across the receiver without the mechanical slack of split designs. You get repeatable zero and stable sight picture from shot to shot. Installation is straightforward—drill and tap or use existing receiver holes depending on your action. Check our FFL transfer pricing if you're coordinating an incoming rifle build. This base accepts standard Weaver-pattern rings and works with most quality optics. Browse our gun store.

Frequently asked questions

Does this base fit all Winchester and LA actions?

The MK4 is engineered for .20 Winchester and .70 LA actions specifically. Verify your rifle's action type before ordering. If you're unsure, bring the rifle in or contact us with the model and serial number.

What ring height should I use with this base?

Ring height depends on your barrel diameter and objective lens size. Low and medium rings are most common with this base. Measure your barrel and optic before selecting rings to ensure proper clearance and sight picture alignment.

Can I transfer ammo through an FFL in Sunnyvale?

Yes — TacticCAL processes ammunition shipments from online sellers under California's ammunition eligibility check requirements. Find gun shop San Francisco at TacticCAL.