The ST0089 is the shorter version of our Top Rail Support for the FX Impact M4. At 23.5 inches and 1 lb 4 oz, it adds the same rigidity along the length of the Impact as the Standard, which is what gives you more precision and better shot-to-shot repeatability, in a length that suits a shorter overall setup.
It is meant for M4 owners who want a stiffer rifle and a solid top rail for optics and accessories but don't need the full 28 1/4 inch length of the Standard ST0088. It also fits earlier FX Impact models.
Why it's built the way it is
A fully disassembled FX Impact is a series of separate assemblies, from the front action back through the plenum to the rear valve area and block, and none of those parts are actually connected to each other. That makes the top rail the single source of rigidity for the whole system, and the TRS replaces the factory rail with a stiffer rail that keeps those components in the same relationship to each other and to your scope from shot to shot.
The shroud support comes in the box with the rail, and running it is optional. It works as a harmonic tuning tool, since connecting the barrel shroud to the rail changes how the barrel system vibrates during the shot, and with some tunes and ammo combinations it produces higher levels of precision, while other setups group best with the barrel free-floated.
The rail has 20 MOA built in for extra scope elevation, a bubble level for checking cant, M-LOK slots on the sides and QD sling sockets on both sides. Saber Tactical has worked with airgunners and precision shooters throughout the sport, and our products have been tested and used in real-world hunting and competition precision shooting.
Specs
| SKU |
ST0089 |
| Length |
23.5 in |
| Weight |
1 lb 4 oz |
| Material |
6061 aluminum |
| Purpose |
Adds rigidity along the Impact action, plenum and valve block |
| Built-in elevation |
20 MOA |
| Accessory slots |
M-LOK on the sides |
| Sling |
QD sockets on both sides |
| Level |
Integrated bubble level |
| Shroud support |
Included in the box; optional to run. A harmonic tuning option that ties the barrel shroud to the rail, and some tune and ammo combinations group best with it while others group best free-floated |
Fits
- FX Impact M4
- Earlier FX Impact models
- Saber M4 Ambidextrous Cheek Rest ST0091 and M4 Cheek Riser ST0090
- Saber Delrin Clamp for TRS Rail ST0041, sold separately as a spare or replacement shroud clamp, which fits the M4 TRS (add the ST0040 bushing if you run the FX carbon fiber tension kit)
Doesn't fit
- Not a replacement for the older 1-3 TRS ST0034/ST0035, which are not M4-compatible
You'll need
- Nothing extra for the shroud support, which comes in the box and is optional to install as a tuning option
Installing and setting it up
Install the rail in place of the factory top rail and tighten it fully before fitting anything else. If you try the included shroud support, fit it once the rail is tight and position it where the shroud naturally sits so it doesn't pull the shroud off line, and if you free-float the barrel, make sure the shroud doesn't touch the rail. When you compare the two setups, keep the tune and ammo the same so the shroud support is the only thing that changes. Check your zero again afterward, since the stiffer setup can shift point of impact compared with how the rifle shot before.
Common questions
Do I need to run the shroud support?
It comes in the box, but running it is optional, because the shroud support is a harmonic tuning tool rather than a required part. With some tunes and ammo combinations, connecting the shroud to the rail produces higher levels of precision, and other setups shoot their best groups with the barrel free-floated. The rail stiffens the action, plenum and valve block either way, so try both setups with the same tune and ammo and keep whichever one your rifle groups better with.
Should I get the Compact or the Standard?
The Compact ST0089 is 23.5 inches long and weighs 1 lb 4 oz, and the Standard ST0088 is 28 1/4 inches long and weighs 1 lb 8 oz, with the same features on both.
Does it work with the M4 cheek rest?
Yes, the M4 Ambidextrous Cheek Rest ST0091 and M4 Cheek Riser ST0090 are designed to work with the M4 TRS rail.
Will it fit my M3?
Yes, it fits the Impact M4 and all previous FX Impact models.
Saber Tactical products are intended for use on airguns only. International customers: adding a restricted item to your cart can limit shipping options. See our return policy for details.
