UM3 mount and Strikefire 2 red dot
Due to aging eyes, I've been looking to alternatives to iron sights at ranges over 15 yards. Beneath that, iron sights are fine - rarely need sights at all for combat fire. But because the front sight has become a bit blurry, it's harder to be consistently precise.
Needing to learn more about red dots, I started with my FNH FiveSeveN. Ordered a UM3 mount from UM Tactical, and picked up a Vortex Strikefire at a reasonable price. I started with a tube optic to begin with - it's versatile and I have an M92 I might SBR, and it would work well there.
The UM3 mount is nice, and performs as advertised. There is one glitch on the FiveSeveN: it only fits on the foremost notch on the lower rail. If you push it back to the second, it comes into contact with a bump that protects the takedown bumper and lightly gouges the polymer. It will go back no further, which leaves the weight of the red dot - about 7 ounces- fairly far forward and the weight pushes down on the front of the slide. Further back, the weight would be closer to the center of gravity, and would not be as noticeable when holding the weapon. It's a simple matter to notch the UM3 mount though, so it's not insurmountable. Other than that minor glitch, the mount performed it's function well. There is a 2" rise from the center of the barrel to the center of the optic. The UM3 slides off and on the firearm smoothly.
The Strikefire optic mounts easily on the UM3 and performs nicely. I didn't bore sight the optic, but started making adjustments at 5 yards, then 10, then 15 an I finally zeroed it at 20 yards. I liked the ballistic calculations better than a 25 yard zero: it gave me a few more usable yards in range before dropping off quickly.
The one nit I have with the Strikefire is the adjustment clicks don't. You can barely feel them, but they are there. It probably took me about 30 minutes to complete the zeroing process because I was being slow and cautious. It still was a smooth process.
Overall, using red dots are going to take a bit of acclimatization, but the precision is there at distance. The 4 MOA dot would be nicer at 2 MOA, but I don't see it being significant, as it 175 yards the calculated round drop becomes more steep and, for my purposes, unusable (-4.9" at 175, -10" at 200). Realistically, shooting outdoors even in mild wind, the light round will suffer in accuracy at those ranges.
Perceived front end movement is more pronounced with a red dot than with iron sights, but it didn't affect accuracy, unless I held the firearm in position too long. The extra weight from the mount and optic (about 9 ounces combined) is noticeable on a 25 ounce (unloaded) firearm.
I'm happy to have made the purchase. I'll get more enjoyment from the FiveSeveN now. The high velocity round (2100 fps for the sporting round) has a relatively flat trajectory. The 2" sight height gives the round a bit more elevation - about 2.1 inches at 75 yards - but not enough to be significant.
Photos and ballistic calculations below.
Growing old is no excuse for growing up.
Last edited by Seraphim; 08-14-2015 at 07:25 PM.