4-40 screw for mounting RDS

[DirectDrive]

Both
my Trijicon RMR and SRO came with 6-32... I do trust Trijicons engineering as a standard for me to judge by.

The longer 4-40 screws thread much deeper. Im also using loctite. I think there is more than enough thread engagement... the question would be screw material shear strength, im not certain what I got though?
There is a marking on top... "YFS".

View attachment 2108999

YFS is a good product.
No idea what grade those would be....you might be able to search it.
It would be nice if the optic could bump against the rear edge of the cut.

 

[spookshack]

I just got the optic this week and havnt reached out to them. I was hoping I could find the screw at Ace hardware.
I did find a screw that works, if less than ideal but it beveled and the correct 3/8" length... does not interfere with extractor, it is odd Swampfox didnt test this for such a common gun (G19)

Also I think the real issue is the slide cut, is the RMR cut without the locating pins and put a "boss" feature where the threaded holes are, which is why 4-40 instead of the usual 6-32. Swampfox included 4 sets of mounting screws in various lengths, but only one of those was 4-40.

I personally am not fond of this modified RMR cut. I have another gun with the dedicated boss pins up front and that optic fit very precise. This modified cut has a lot of slop and very much needs the bevel to align.... i dont like that with smaller weaker screws. But I guess it works enough that slides are made that way.

AimSurplus, LLC

Might reach out to SF and see if you can get just a couple vs buying the complete kit linked above.

 

[Koda]

AimSurplus, LLC

Might reach out to SF and see if you can get just a couple vs buying the complete kit linked above.

That kit might be the only way to get the exact screw. I will have to email Swampfox to see if I can score just a few and if not I'll maybe order that kit.
The choice now is that the csk screws I bought are the perfect length and holding fine. I have a hex driver bit I ordered on the way so I can properly torque them. This optic went on a backup/spare gun so no hurry on this project, though I am anxious to zero the Swampfox.

 

[jbett98]

I passed by Winks Hardware in SE Portland last Friday and they have lots of oddball fasteners.

 

[Koda]

Well I finally go around to putting the correct screws in. I contacted Swampfox and they were no help just directed me to their screw kit to buy that was out of stock. The Aimsurplus link in this thread still had them though so I ordered the kit, $16.99 plus shipping just to have the correct 2 oval head Swampfox screws with the#10 torx driver... they come extra long requiring me to modify and grind down to the correct length. The kit contained screws for all of their optics for whatever thats worth.
I clamped the tiny screws in a work vise with leather to protect the screw heads and used an angle air grinder with a sanding disk. I went slow, carefully chamfered the thread tips, tested the length in the slide, repeat process until the screw does not protrude into the extractor hole. I don't have a good way to correctly measure the true length of oval head screws, so the overall length that worked for me was about .410". By "eye" using the caliper tips, the true/correct length came out at 3/8"... so the correct screw to have ordered should be a 4-40x3/8" long oval head #10 torx screw, if I could ever find any. The csk version also works perfect.
For reference now that I'm here typing, here is a pic of what I call the "modified RMR" cut, without the two recoil bosses up front to align the optic. The original RMR cut does not have threaded bosses and uses 6-32 threads in those locations.



For all the effort I do think the oval head screws look better than the csk screws. Now I need to find the time to zero the optic.

 

[obesechess]

My go to fastener store is General Threaded in SE Portland. If anybody had them, they would.
The owner might mail you some. He's the most helpful counter person I've ever dealt with.

General Threaded Products Co

With a commitment to excellence, this hardware store specializes in providing high-quality threaded products and fasteners essential for a range of industria...

general-co.edan.io

Thanks. I'm about to put a lot of wear and tear on a cheap optic - for science - and want to bolt it down with the strongest screws I can find, these folks are just up the road from me and I had no idea.

M4-Coarse x 9.4mm. Ridiculous.

@Koda I may have missed this - is that an original "modification" done on the slide, or is that from the factory? Sorry to hear Swampfox's customer service wasn't all that. I've heard very good things about their optics for the price and their customer service, though haven't bought anything from them myself.

 

[jbett98]

The owner of General Threaded is a hoot. Very laid back and fun to deal with. Take a look up towards the ceiling when you walk in the door.
He's got that mid west drawl and humor that makes your day.

 

[Koda]

@Koda I may have missed this - is that an original "modification" done on the slide, or is that from the factory? Sorry to hear Swampfox's customer service wasn't all that. I've heard very good things about their optics for the price and their customer service, though haven't bought anything from them myself.

Not a mod, from the factory. Its an aftermarket slide. A web search shows this is not uncommon version of the RMR footprint.

 

[obesechess]

Got it! I've only got RMSc and stock slides on my pistols so I wasn't sure. Learn somethin' new every day!