SAG MK4 Upgrade Kit – Gas Tube Upper + Rear Cover
- $719.00
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SAG MK4 Upgrade Kit – Gas Tube Upper + Rear Cover
CNC-Machined Aluminum | Integrated Gas Tube Upper | Removable 1913 Rear Cover | Fits All MK1 Platform Versions
The SAG MK4 Upgrade Kit (S20132) by Sureshot Armament Group converts your existing MK1 handguard into a full MK4 chassis. The kit adds an upper with an integrated gas tube and the removable rear receiver cover with its own 1913-MIL-STD segment – completing the MK4 architecture over your MK1 handguard block.
Once installed, the resulting MK4 chassis free-floats the barrel inside the tubular handguard and provides a continuous 1913-MIL-STD top monorail from the gas block to the end of the shortened receiver cover. The front rail stays on during field-stripping, the stock still folds completely, and the iron sights are not blocked. The removable rear cover rail is intended for optics that don't need to retain zero (magnifier for a red dot, NV attachment). The kit is universal – it fits all MK1 platform versions (AK-pattern, Saiga-308, VPO/Molot).
? This Is an Upgrade Kit – Not a Complete Chassis
The kit includes only the gas tube upper and the removable rear cover. The MK1 handguard block is NOT included – you must already own an MK1 handguard. If you don't have an MK1, choose the complete MK4 chassis instead (available as a separate product).
? Key Advantages
- Converts MK1 ? MK4 – complete the chassis architecture you already started
- Universal fit – works with all MK1 platform versions
- Integrated gas tube upper – continuous 1913 monorail over barrel and receiver
- Removable rear cover rail – 1913 segment for magnifier or NV attachment
- Cost-effective – upgrade without re-buying the handguard block
- CNC-machined aluminum – matches your MK1 in quality and finish
Technical Specifications
| Material | High-Strength Aluminum Alloy (CNC-milled) |
| Product Code | SAG-S20132 |
| Kit Contents | Gas tube upper + removable rear receiver cover |
| Requires | MK1 handguard (any platform version) – not included |
| Rear Cover Rail | 1913-MIL-STD segment (removable section) |
| Result | Full MK4 chassis: free-floating barrel + continuous 1913 top monorail |
Compatibility
Universal – fits all MK1 handguard platform versions (AK-pattern, Saiga-308, VPO/Molot). See the compatibility filter on this page.
Important: The assembled chassis is not suitable for self-installation on full-size carbines built on certain Molot Arms AKM-pattern receivers (MA-136-02, MA-136C, MA-136-05). For those platforms, installation must be performed in a gunsmith workshop.
What's Included
- (1) Gas Tube Upper (integrated 1913 monorail section)
- (1) Removable Rear Receiver Cover (with 1913 segment)
- (1) Mounting Hardware Set
- (1) Installation Manual
Note: MK1 handguard block NOT included.
FAQ
Q: What do I need to use this kit?
A: An MK1 handguard (any platform version). The kit adds the upper and rear cover to complete the MK4 chassis.
Q: Does it fit my MK1 version?
A: Yes – the kit is universal and fits all MK1 platform versions (AK-pattern, Saiga-308, VPO/Molot).
Q: I don't own an MK1 – can I use this kit?
A: No – choose the complete MK4 chassis instead, which includes the handguard block.
Q: What does the rear cover rail hold?
A: Optics that don't require zero retention – such as a red dot magnifier or an NV attachment.
Q: How does shipping work?
A: US orders are fulfilled and delivered through our partner's domestic US logistics network. Delivery is not express, but it is reliable and fully guaranteed.
Upgrade Your MK1 to a Full MK4
? In Stock ? Guaranteed US Delivery ? CNC-Machined Quality
SAG Specs
General
Recommended
SAG, Sureshot Armament, MK4 Upgrade Kit, Upgrade Kit, Gas Tube Upper, Rear Cover, MK1 Conversion, Chassis Upgrade, 1913 Rail, Chassis Systems, Bazalet