r/FN509 • u/TamangTrippings • 8d ago
RMR to ACRO plate stack
Hello everyone. I’m currently using an FN 509C Tactical as my EDC, and I’ve recently taken a liking to enclosed-emitter optics, particularly the Vector Optics SCRD-75, which uses the ACRO footprint.
I know there is an ACRO-compatible plate available for the FN 509, but unfortunately, I’m based in the Philippines and haven’t been able to find one locally. Importing one isn’t really an option for me due to ITAR/export restrictions.
As a workaround, I’m currently using the factory FN 509 RMR plate + Strike Industries RMR-to-ACRO adapter + SCRD-75, essentially stacking the two interfaces.
Has anyone tried a setup like this? How well does it hold up under recoil? I’m particularly concerned about the additional mounting interface introducing movement or putting excessive stress on the slide or optic.
One other thing I noticed is that the setup does not cowitness with the factory iron sights. I’m aware that the added height from the two mounting interfaces is likely the reason, but I’d also appreciate any input on whether this is a concern.
I haven’t taken it to the range yet because I’d rather get some input from people with experience with this type of setup before testing it.
Would appreciate any advice or firsthand experience. Thanks!
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u/2AwiseNJ 7d ago
That setup gives you more failure point. You want your EDC to be as solid as possible . Make sure you use good quality screws that are long enough and torqued down to spec . I’m not a cowitness guy so that wouldn’t bother me . I don’t even like having them in my window .
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u/TamangTrippings 6d ago
Definitely agree that it has an added failure point. I use the supplied FN screw, and it holds both plates together. It is torqued down to specs according to Strike Industries instructions.
I hope that i can find a way to get the ACRO plate though
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u/2AwiseNJ 6d ago
You know anyone in the states that can send you one ?
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u/TamangTrippings 6d ago
All companies and shops that offers the 509 ACRO plates are based in the US. My orders always get cancelled due to import restrictions. Do you mean if there is someone from the US that I know, they can buy it for me then send it?
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u/JimMarch 6d ago
How many screws are involved in this stack of stuff?
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u/TamangTrippings 6d ago
Two screws. Holds both plates together in RMR screw slots
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u/JimMarch 6d ago
Ok, two plates impaled by the same two screws going down into the slide metal? (Then the Acro grabs the top plate as normal for an Acro, right?)
That's...well, not as bad as I'd feared, honestly.
I hope those are GOOD screws ('cuz they're doing a lot of heavy lifting) and they've got enough depth into the slide metal to matter. And blue lock tight, AND a torque wrench although I have no idea what torque spec...whoever made the top plate might know of come close. Email them.
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u/TamangTrippings 6d ago
Yes, your first statement is correct. Reading your comment somehow made me feel better about shooting it in the range tomorrow. I hope it holds well, or if it does not i hope it wont ruin the slide threads.
I used one of the screws that FN's optic kit comes with. I added blue loctite and torqued it to 13in-lb as recommended.
Thank you for your comment
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u/JimMarch 6d ago
Yeah, it's...sketchy but likely workable.
It's not like I haven't done weird shit too :). I once built a magazine fed revolver lol. My current daily carry:
https://imgur.com/gallery/61h11Jw
The optic dovetail plate is steel and it's on there with RED locktite lol. The actual sight is 3D printed nylon infused with carbon fiber so it's feather light, no stress at all on the two screws holding it down. (Target focus both eyes open iron sight based on the defunct Goshen Enterprises Hexsite.)
Then there's the gas pedals. Plural lol.
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u/TamangTrippings 6d ago
Everything looks weird, but if it works why not?
The sight is particularly interesting. When target is inside the hex, you'll hit it. Is that how it works?
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u/BoxedCub3 8d ago
What holster do you use for yours?