Mossberg 500A 12 Gauge Pump-Action, 18.5" Barrel, 5+1, Custom Setup with Heat Shield, Receiver Rail & Side-Saddle, Collapsible Stock
This Mossberg 500A is a customized 12 gauge pump-action shotgun configured for practical, ready-to-use versatility. It features an 18.5" barrel with a brass-bead front sight, a receiver-top Picatinny rail with an integrated 6-round side-saddle, a perforated barrel heat shield, and AR-style adjustable furniture. Marked "Mossberg — Made in U.S.A. — North Haven, Conn. — 500A — 12 GA.", it combines proven 500-series internals with useful, installed upgrades.
Condition
Overall Condition: Good condition, showing some signs of prior use and handling.
Bore Condition: Excellent - Clean, mirror finish, no signs of wear.
Specific Condition Notes: There are markings from previous handling and use, and there are signs of surface rust throughout.
What’s Included
- Receiver-top Picatinny rail with integrated sidesaddle shell carrier (installed)
- Perforated metal barrel heat shield (installed)
- AR-style 6-position collapsible buttstock (installed)
- Textured pistol grip on receiver adapter (installed)
- Front barrel/magazine clamp with sling swivel attachment (installed)
The 18.5" barrel uses a simple brass-bead front sight and is marked "CHAMBERED FOR 2 3/4 AND 3", supporting both 2 3/4" and 3" shells. The internal tubular magazine is owner-confirmed at 5+1 with 2 3/4" shells. The bore is bright and clean.
Core 500-series operating features include twin action bars, dual extractors, and an anti-jam elevator for consistent cycling. The top-tang safety is ambidextrous, and the receiver is drilled and tapped for optics. The receiver is an anodized-black aluminum alloy.
This example is outfitted with a receiver-top Picatinny rail that integrates a 6-round side-saddle shell carrier, providing on-gun ammunition storage. A perforated barrel heat shield is installed for added barrel coverage. A front barrel/magazine clamp with sling swivel attachment is included.
The furniture includes an AR-style 6-position collapsible stock paired with a separate pistol grip and a ribbed synthetic forend. The stock is adjustable to suit different users and setups, and the length of pull is listed at 13.0.
Overall, this U.S.-made 500A combines Mossberg’s proven pump-action design with practical, installed enhancements that emphasize carry, handling, and accessory flexibility.