Will the Harris #2A adapter fit my solid wood Ruger M77 stock?

No, the Harris #2A adapter is specifically engineered for hollow synthetic and plastic fore-ends like those found on the Ruger M77 MKII and All-Weather synthetic stocks. Solid wood stocks require traditional wood-screw studs rather than this internal round head flange nut design.

What is the primary technical advantage of the 5/8-inch round head flange nut?

The 5/8-inch circular round head flange nut is designed to seat neatly inside narrow or restrictive internal channels of thin-walled synthetic fore-ends. It distributes clamping pressure over a wide internal surface, which prevents the swivel stud from pulling through the plastic stock material under heavy recoil or sling tension.

Does this mounting adapter require any electrical certifications or permits for use in Australia?

No, the Harris #2A adapter is a purely mechanical firearm accessory containing no electronics, meaning 240V mains compatibility, SAA/RCM certifications, and electrical regulations do not apply. Furthermore, it is an unrestricted hardware part requiring no special import permits, though users must ensure their rifle modifications comply with relevant state and territory firearms regulations.

Which bipods from the XHunter range pair best with this adapter once installed?

Once the #2A adapter provides the necessary front sling swivel stud on your synthetic Ruger stock, you can directly attach standard swivel-stud-mounted bipods such as the Harris HS-BR 6 to 9 Inch Swivel Bipod or the Harris H-L 9 to 13 Inch Hunting Shooting Gun Rest Bipod.

Ruger M77 Sling Adapter - Harris HADAP2A

The Harris Engineering No. 2A Adapter (HADAP2A) is a firearm mounting hardware component engineered specifically to install a forward sling swivel stud into hollow synthetic and plastic rifle fore-ends. Designed primarily for Ruger Model 77 (M77) RP MKII plastic fore-ends and Ruger All-Weather synthetic stocks, this adapter provides the necessary internal structural support to mount standard QD hunting slings and swivel-stud-attached bipods, including Harris Series 1A2 and Series S models.

Key Features

Internal Pressure Distribution: Utilises a circular flange nut that seats inside the narrow internal channel of hollow plastic stocks, distributing clamping force across the stock wall to prevent the stud from pulling through under tension or recoil.
Optimised Internal Profile: Features a round head design that fits rounded or restrictive internal fore-end channels without the extensive stock inletting required by wider rectangular backing plates.
Standard Stud Interface: Supplies an external standard sling swivel stud on smooth synthetic stocks, establishing direct compatibility with sling hardware and bipods.
Mechanical Hardware Design: Manufactured in the USA as an entirely mechanical, non-powered component suitable for standard hunting calibres used across the Ruger M77 MKII platform.

Specifications

Product Type: Rifle bipod and sling swivel stud mounting adapter
Manufacturer: Harris Engineering, Inc. (Made in USA)
Model / MPN: No. 2A / HADAP2A
Flange Nut Diameter: 5/8-inch (approx. 15.88 mm) circular round head
Primary Firearm Compatibility: Ruger Model 77 (M77) RP MKII synthetic fore-ends, Ruger All-Weather synthetic stocks, and narrow hollow composite stocks
Bipod Compatibility: Harris Series 1A2, Series S, and standard swivel-stud-mounted bipods
Estimated Hardware Weight: Under 20–30 g

Who is the Harris No. 2A Adapter for?

Ruger M77 MKII Synthetic Stock Owners — Requires an internal 5/8-inch (approx. 15.88 mm) circular round head flange nut to seat within the curved internal channel of hollow plastic fore-ends, enabling the secure mounting of a Harris bipod without pulling through the thin-walled synthetic material.
Hunters Modifying Hollow Plastic Rifle Stocks — Relies on the 5/8-inch (approx. 15.88 mm) round backing flange of this bipod mounting adapter to distribute tension across hollow polymer fore-ends lacking a factory front sling attachment point.

Less suitable for: Solid wood stocks or thin-walled wood fore-ends with internal clearance constraints; solid timber requires direct wood-screw studs, while wood fore-ends with gas tubes require radiused backing plates rather than a 5/8-inch round flange nut. It is also unsuitable for Ruger 180-series or factory folding stocks.

SKU	HR40925LP
Model #	HADAP2A
Brand	Harris
Shipping Weight	1.0000kg

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Harris Hadap2a Adapter Round Head Flange Nut Ruger M77

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