Last updated: March 2026
The Aimpoint ACRO and Holosun 509T are both closed-emitter red dots designed for pistol use. The ACRO P-2 offers 50,000-hour battery life and military-grade durability at ~$500. The 509T offers solar backup, multiple reticle options, and lower price (~$350). For duty and long-term reliability, the ACRO wins. For value and features, the 509T is hard to beat.
Why Closed-Emitter Optics Matter for Pistols
Traditional open-emitter red dots — like the popular Trijicon RMR or Holosun 507C — have the LED emitter exposed. Dust, rain, or debris on the emitter can temporarily reduce dot visibility. Closed-emitter designs like the Aimpoint ACRO and Holosun 509T protect the emitter behind a front lens, keeping it functional even with debris on the glass.
For duty carry, everyday carry, and any environment where the gun might be exposed to the elements, closed-emitter designs offer meaningful protection. Here’s how these two top options compare.
Specs Comparison
| Specification | Aimpoint ACRO P-2 | Holosun 509T |
|---|---|---|
| Emitter Type | Closed (protected) | Closed (protected) |
| Dot Size | 3.5 MOA | 2 MOA dot / 32 MOA circle / both |
| Battery Life | 50,000 hours (CR2032) | 50,000 hours LED (+ solar) |
| Solar Backup | No | Yes ✅ |
| Brightness Settings | 10 (2 NV compatible) | 12 |
| Window Size | 27x20mm | 28x23mm |
| Weight | 47g | 60g |
| Water Resistance | IP68 (submersible) | IP67 (submersible) |
| Shake Awake | No | Yes ✅ |
| Compatible Footprint | ACRO footprint | 509T footprint |
| Price | ~$480–$520 | ~$330–$380 |
| Made In | Sweden | USA (some components from China) |
The ACRO P-2: Military-Grade Closed Emitter
The Aimpoint ACRO P-2 is the current Aimpoint pistol offering, upgraded from the P-1 with improved electronics and 50,000-hour battery life. Aimpoint optics have been standard issue for Swedish military and Tier 1 U.S. special operations units. Their track record for surviving extreme conditions is unmatched in the optics industry.
The ACRO footprint is specifically adopted by the S&W M&P9 M2.0 Metal‘s factory-milled slide, meaning direct mounting without additional plates or adapters.
What you don’t get with the ACRO: solar backup, shake-awake activation, or multiple reticle options. It’s a single-purpose, extremely high-reliability closed emitter dot. That simplicity is part of the design philosophy.
The Holosun 509T: Feature-Rich Alternative
The Holosun 509T matches the ACRO’s battery life (50,000 hours LED) and adds solar backup — meaning even in bright conditions with a dead battery, the optic continues to function. The Multi-Reticle System (MRS) lets you switch between a 2 MOA dot, 32 MOA circle, or both. Shake-awake activates the dot when the gun moves.
For the price difference (~$150 less than the ACRO), the 509T delivers more features. The question is whether those features justify using a non-ACRO footprint optic on a gun specifically milled for the ACRO.
Which Fits the M&P9 M2.0 Metal Better?
The M&P9 M2.0 Metal is factory-milled for the Aimpoint ACRO footprint specifically. The Holosun 509T uses a different footprint and requires an adapter plate to mount on the ACRO-milled slide. This adds height, reduces cowitness precision with the factory suppressor-height irons, and adds a potential point of failure (the adapter plate).
For the M&P9 M2.0 Metal specifically: the ACRO is the purpose-built solution. For guns with universal optic plates or other footprints, the 509T is a better value proposition.
Pros & Cons
Aimpoint ACRO P-2
- ✅ 50,000 hours — longest-rated battery life in class
- ✅ Military-proven track record
- ✅ Direct mount on ACRO-footprint slides (no adapter)
- ✅ IP68 water resistance
- ❌ No solar backup
- ❌ More expensive (~$150 more)
- ❌ Single reticle option (3.5 MOA)
Holosun 509T
- ✅ Solar backup — works even with dead battery
- ✅ Shake-awake convenience
- ✅ Multiple reticle options
- ✅ Lower price
- ❌ Requires adapter plate on ACRO-cut slides
- ❌ Slightly larger and heavier
Our Recommendation
If your gun has an ACRO-specific slide cut (like the S&W M&P9 M2.0 Metal), buy the Aimpoint ACRO P-2. The direct mount, cowitness alignment, and military-grade reliability are worth the premium when matched to a slide specifically designed for it.
If your gun has a universal adapter plate system, the Holosun 509T’s solar backup and lower price make it a strong alternative. Browse our handgun category and see the SIG P365 FUSE Comp for a factory optic solution that ships with the optic already installed and zeroed.
Frequently Asked Questions
Can the Holosun 509T mount directly on an ACRO-cut slide?
Not without an adapter plate. The ACRO footprint and 509T footprint are different. Using an adapter plate works but adds height and an additional component to the mounting system. For ACRO-cut slides, the ACRO P-2 is the purpose-matched solution.
How long does the Aimpoint ACRO battery last in practice?
50,000 hours at setting 6 of 10. At higher brightness settings, battery life reduces, though still extremely long by any practical measure. Most duty users replace the battery annually as a policy even when the battery is not exhausted — at that interval, battery life is not a concern.
Is the Holosun 509T as durable as the ACRO?
Holosun has improved substantially over the years and the 509T has a good field reputation. Aimpoint’s track record is longer and in more extreme environments. For civilian range use and carry, the 509T is durable enough. For extreme duty environments, the ACRO’s proven track record provides higher confidence.
What does “closed emitter” mean in practical terms?
In a closed-emitter design, the LED that creates the aiming dot is protected by a front glass lens. Open-emitter designs leave the LED exposed. In rain, dust, or a muddy environment, a closed emitter can be wiped clean and continue functioning; an open emitter with fouled LED may have reduced dot visibility.