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Discussion Starter #1
I'm curious. I have CMMG side rails for the PS90 that use low head socket cap screws. I had to get longer screws to mount my Compact ACOG using the msw Compact ACOG mount.

Do any of the side rails out there use screws with a 45 degree countersunk head? I think the Halo side rails might, but can't tell from their pictures and they haven't responded to my email yet.
 

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Discussion Starter #3
Cool, thanks. I see those are the extended rails. It doesn't look like Magparts offers standard length rails :(
 

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Discussion Starter #5
Hmmm... Looking at the MPF rails I'd guess those are plain old socket head cap screws.

I think a side rails using countersunk fasteners would work best with the msw Compact ACOG mount. To use the msw mount you have to use undersize fasteners that pass through the receiver side rail holes. Having to use the undersize fasteners makes for kind of a sloppy fit on the side rails. This is no biggee, once you tighten the fasteners everything stays put well. With a 45 degree countersunk fastener though the undersize screw would self center on the side rails and take out any side rail slop.
 

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Discussion Starter #7
Hey Metroplex.

Doh! I thought you had the Halo side rails for a sec there. The pic for their tri-rail is good enough to tell it uses countersunk screws, but I can't tell 100% from their pic of their side rails if they use countersunk screws or not.

I can't use the tri-rail with the msw ACOG mount. I'm looking for regular length side rails only that use countersunk fasteners.
 

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Discussion Starter #8
I called Halo today and they said their side rails do take countersunk screws.

Now I need to figure out if replacing the M5 countersunk screws with 8-32 countersunk screws will work OK. Looks like the metric countersink standard is 90 degrees and the english standard is 82 degrees.
 
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