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Sightmark
Overview
The Sightmark Core Shot A-Spec FMS is a robust red dot sight designed for quick target acquisition and enhanced accuracy. Featuring a durable aluminum construction and a red reticle, this optic is optimized for use on firearms equipped with a Picatinny mounting interface. Builders often incorporate this sight into mid-length gas system AR-15 builds chambered in 5.56 NATO, making it a practical choice for a variety of shooting applications.
Sightmark Core Shot A-Spec FMS 1x28x18mm Red Dot Sight - SM26017 was the tenth most added optic on GunPartPicker in August 2026, behind the Trijicon ACOG 4x32mm Scope - Dual Illuminated Chevron - Red, with about 2% of all optics added to builds. Down from #9 in July. Builds with this optic are mostly chambered in 5.56 NATO (83%, then .223 Wylde 11%), mostly on mid-length gas (62%, then carbine-length 23%), and mostly AR-15 (90%).
Availability is good: it was in stock at one retailer or another nearly every day in August 2026, and today 5 of the 7 retailers we track have it in stock. Prices barely moved in August 2026, holding around $129.97, so there haven't been real sales lately. Buying today, the lowest price is $129.97 at Classic Firearms, which matches the best price we saw in August.
Updated · from real builds on GunPartPicker · Prices checked · refreshed daily across 31 retailers
We ranked every optic by how often it shows up in real builds on GunPartPicker.
Read the guide: AR-15 Red Dot & Optic Guide →The part most often added in each category by the 185 builds that include this one
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Aggregated and anonymized data showing how builders use this product
Builds in the community that include the Sightmark Core Shot A-Spec FMS 1x28x18mm Red Dot Sight - SM26017
| Build | Parts | Total |
|---|---|---|
 | 28 | $1933.44 |
 | 15 | $1121.77 |
 | 8 | $1336.18 |
 | 14 | $947.71 |
 | 24 | $5204.22 |
 | 12 | $3448.65 |
 | 29 | $2017.90 |
 | 18 | $2363.20 |
 | 14 | $970.04 |
| 27 | $1771.35 |
 | 11 | $2400.95 |
1 global rating
Top reviews
Sightmark Core Shot A-Spec FMS red dot has clear glass with no edge distortion. Zero held through a 500 round day. Battery life is good on auto-off mode. Reticle is crisp at 2 MOA. Solid budget red dot for any build.
