The EGW Mossberg 100 ATR/4X4 Long Action scope base gives you a solid one-piece Picatinny rail for your Mossberg without the hassle of drilling and tapping. Built from 6061 T6 aluminum and precision-machined to MIL-STD 1913 specs, this mount drops straight onto your rifle's factory receiver holes and accepts both Picatinny and Weaver scope rings. It's a straightforward upgrade if you want to swap optics or dial in better eye relief without permanent modifications.
EGW engineered these bases with a milled center channel to keep weight down while maintaining rigidity where it counts. The full-width cross-slots are gauged tight—±.002"—so you get consistent, repeatable performance from shot to shot. Installation is no-fuss: the base comes with socket head Torx screws and a wrench, and EGW recommends 20 inch-pounds of torque plus a touch of blue loctite for a secure fit that'll stay put.
If you're running a Mossberg 100 ATR or 4X4 Long Action and want to upgrade or customize your optics setup, this one-piece Picatinny base gives you the flexibility to run modern scope rings and mounts without gunsmithing. It's the kind of practical accessory that pays for itself the first time you need to change scopes or adjust sight picture.
Key Features
- One-piece Picatinny rail mounts directly to factory receiver holes—no drilling or tapping required
- 6061 T6 extruded aluminum construction for durability and light weight
- Accepts Picatinny or Weaver scope rings for maximum flexibility
- Milled center channel reduces weight without compromising rigidity
- Precision-machined cross-slots gauged to MIL-STD 1913 ±.002" tolerance
- Includes socket head Torx screws, wrench, and installation torque spec (20 inch-lbs)
Specifications
| Firearm Compatibility | Mossberg 100 ATR / 4X4 Long Action |
| Mount Type | One-piece Picatinny rail |
| Rail Standard | Picatinny (accepts Picatinny or Weaver rings) |
| Material | 6061 T6 extruded aluminum |
| MOA | 0 MOA |
| Installation | Mounts to factory receiver holes; no drilling required |
| Recommended Torque | 20 inch-lbs (with blue loctite) |
Frequently Asked Questions
Will this base fit my Mossberg 100 ATR or 4X4 Long Action?
Yes. The EGW base is drilled to match the factory scope mount holes on these Mossberg Long Action receivers, so installation requires no additional drilling or tapping.
Can I use Weaver scope rings with this Picatinny rail?
Yes. The base accepts both Picatinny and Weaver scope rings, giving you flexibility in ring choice and allowing easy swaps between optics.
What hardware comes with the mount?
The base includes socket head Torx screws and a wrench. EGW recommends tightening to 20 inch-pounds of torque and applying a small amount of blue loctite to the fasteners for a secure, repeatable fit.
Will I need a gunsmith to install this?
No. Since the base mounts directly to the factory receiver holes, installation is straightforward and requires no drilling, tapping, or gunsmithing.
