Optic Weight Comparison: How Different Red Dots Stack Up on Milled Glock Slides vs the Factory Glock 47 MOS

We will examine the differences between slide weights with different milling options and the variances of popular optics for shooting USPSA.

Weight Breakdown of Each Optic

1. Trijicon SRO with Factory Glock 47 Slide/Plate/Sites (13.7 oz)

The Trijicon SRO is a well-known, rugged, and proven optic. We will use this as our baseline. Weighing in at 13.7 ounces, this will be our proven factory-tested baseline for comparison. The drawbacks of this system are that it uses the MOS plate system, which for high round count use is not proven to last given the whole optics system is only held to the slide with 2x M3 screws. We often see broken and/or loose screws with this plate system.

2. Vortex Defender XL On a Milled Glock 17 Gen 5 Slide With a Front .315 Angry Bear BUIS sight. There is no rear sight or dovetail as this footprint on the factory Non-MOS slide is too long (13.4 oz)

Slightly lighter than the Trijicon SRO, the Vortex Defender XL registers at 13.4 ounces. Even though the Vortex Defender XL weighs more, more material is removed from the slide to accommodate the longer footprint.

3. Holosun 507 Comp (13.6 oz) On a Milled Glock 17 Gen 5 Slide with .315 Tall Angry Bear Black BUIS

The Direct Milled Glock 17 Gen 5 slide with Holosun 507 Comp comes in at 13.6 ounces, nearly identical to the SRO on a Glock 47. This is an affordable and proven optic with many options on the RMR footprint.

4. Trijicon SRO Race cut with no dovetail or BUIS and Glock 17C style ports on the Glock 17 Gen 5 (12.9 oz)

This combination is only 12.9 ounces. This reduction in weight could be beneficial for faster target acquisition and reduced slide resistance, making it a top contender for competitive shooters. The C-style ports cut .5 oz off the top front of the slide.

Key Takeaways

• The Trijicon SRO comes in at 1.6 oz and is the lightest optic tested.
• The Holosun 507 Comp comes in at 1.7 oz and is virtually similar to the SRO when comparing weights.
• While the Vortex Defender XL is the heaviest optic at 1.93 oz, the material removed makes it similar in total slide weight, given that more material is milled from the slide for the more extended DPP footprint.
• C Style Ports remove an additional .5oz from the top front of the Glock 17 Slide

Conclusion

The Glock 47 removes weight from the top underside of the slide to compensate for the added weight of the longer dust cover to accommodate the shorter Glock 19/45 recoil spring. There is an advantage to removing weight from the upper half of the slide vs. the lower half, as a lower slide center of gravity can provide more of a push compared to the flip of a slide with weight biased to the top half.

To be clear, the Glock 47 using a shorter spring does not provide a shorter stroke. As seen in the image comparison, the wear of the barrel lug is identical to the Glock 17 Gen 5.

When direct milling a Glock 17 slide, weight is removed from the top rear, which is beneficial. Removing the additional .5 oz from the top front of the slide will be an added benefit, as this bias of weight is high and forward on the slide’s return to battery.

The Glock 17 offers more recoil spring options as the spring space is more extended. The factory Glock 17 Gen 5 spring weight is 17 lbs vs the 18 lbs spring used in the Glock 47. The shorter spring space will require a stronger spring to fully function, thus reducing options for lighter spring choices while maintaining reliability.

I personally prefer the 17 slide with the factory recoil spring, direct milled for a race cut with no rear dovetail, no backup sights, and the C-style ports cut in the front top of the slide. This lowers the slide's top weight while maintaining 100% reliability with the factory spring. An added benefit is that I can swap in a C-ported Glock 17 Gen 5 barrel and enjoy the added compensation benefits without changing the point of impact.