The Gemtech GM-45/Blackside threaded rear mount adaptor is a 5/8x24 thread pitch accessory designed to allow fixed-barrel weapons to run with GM-45 or Blackside suppressors. If you're running a bolt-action or other fixed-barrel platform chambered in 300 Blackout, this adaptor bridges the gap between your barrel's threads and the suppressor's mounting system, giving you the option to add sound suppression without a quick-detach setup.

This is a straightforward mechanical solution for shooters who want subsonic 300 Blackout capability with Gemtech's proven suppressor line but don't have removable-barrel or quick-detach-compatible platforms. The adaptor itself is passive—it simply provides the threading interface—so reliability and durability come down to solid construction and proper installation. As always with suppressors and muzzle devices, ensure your barrel threads match the 5/8x24 specification before ordering.

One critical note: both the GM-45 and Blackside suppressors are rated for 300 Blackout with subsonic ammunition only. That means standard velocity 300 Blackout loads are off the table; you'll be running dedicated subsonic rounds to stay within the suppressor's design parameters and preserve performance and safety.

Key Features

• 5/8x24 thread pitch for compatibility with standard 300 Blackout barrels
• Enables fixed-barrel weapons to use GM-45 and Blackside suppressors
• Simple threaded interface—no moving parts or maintenance required
• Rated for subsonic 300 Blackout ammunition only

Specifications

Brand	Gemtech
Model	12194
Thread Pitch	5/8x24
Caliber/Cartridge	300 Blackout (subsonic only)
Suppressor Compatibility	GM-45, Blackside

Frequently Asked Questions

Will this adaptor work with my 300 Blackout barrel?

Yes, provided your barrel is threaded 5/8x24. This adaptor mates directly to that thread pitch and allows you to attach a GM-45 or Blackside suppressor to a fixed-barrel weapon.

Can I use this with standard velocity 300 Blackout ammo?

No. Both the GM-45 and Blackside suppressors are rated for subsonic 300 Blackout ammunition only. Standard velocity loads exceed the suppressor's design limits.

What suppressors is this adaptor compatible with?

The Gemtech GM-45 and Blackside suppressors. It is not compatible with other suppressor models.

Is this adaptor a permanent installation?

It threads onto your barrel and is removable via unthreading, so it's not permanent. However, once installed for a fixed-barrel setup, it typically remains in place as part of the suppressor mounting system.