Acetech Bifrost MKII Tracer Unit — Rainbow Flame, 14mm CCW

The original Bifrost earned its reputation by keeping up when the rate of fire climbed. The MKII takes that and adds the thing people actually notice from across a field: multi-colour rainbow flame effects at the muzzle, produced by high-intensity RGB LEDs and beam-tracking optics rather than a single fixed colour.

You get four lighting modes, cycled with the rear power button. Rainbow flame for maximum spectacle, single RGB colour if you want a consistent look, pure flame for a fiery orange muzzle blast that suits milsim, or tracer only when you just want to see where your rounds are going. It changes the character of the gun entirely depending on which you pick.

The tracer side is where the engineering matters. High-power internal LEDs charge green luminous tracer BBs to a genuinely bright trace, and the optical sensors hold that illumination consistently at up to 35 rounds per second. That covers fast AEGs, HPA builds and snappy gas blowback pistols without the trail thinning out in the middle of a burst — which is exactly where cheaper units give up.

Practical details are well judged. It powers on automatically when it detects movement and sleeps after inactivity, so you are not flattening the battery because you forgot to switch it off. The lithium cell charges over USB-C and delivers thousands of shots per charge. The shell is anodised CNC aluminium alloy rather than polymer.

Threading covers both ends of a loadout: 14mm CCW female as standard, with a 11mm CW adapter included in the box, so the same unit moves between a rifle and a pistol without buying anything extra.

Specifications

Good to know before you buy

The tracer function needs green luminous tracer BBs — the unit charges them as they pass, and standard BBs will not glow. The flame effect works with any ammunition, so you get something out of it either way.

Check your site’s rules before a night game. Most UK sites are fine with tracer units, but a few restrict bright muzzle effects indoors.

Frequently asked questions

How is it different from the original Bifrost?
The MKII adds multi-colour rainbow flame effects and four switchable lighting modes, in an upgraded compact housing. The original produces a single-colour effect. Both charge green tracer BBs; the MKII tracks up to 35 RPS.

Do I need tracer BBs?
For the tracer function, yes — green luminous BBs. The flame effect at the muzzle works with any standard BB, so the unit still does something without them.

Will it fit my pistol?
Yes. It is 14mm CCW female as standard and a 11mm CW adapter is included, which covers most gas pistols as well as rifles.

Will it keep up with my HPA gun?
Up to 35 rounds per second, which covers fast AEGs, HPA builds and gas blowback pistols. That is where slower units start losing the trail mid-burst.

How do I change the mode?
Press the rear power button to cycle through rainbow, single colour, flame only and tracer only.

Will it drain the battery in my bag?
It powers on when it senses movement and sleeps automatically after inactivity, which limits that. Charge over USB-C before a night game as a matter of habit.