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Holosun 507c on CHPWS plate screws?

1276 Views 5 Replies 5 Participants Last post by  ddc
Does anyone definitively know the correct installation procedure and what screws to use for installing a Holosun 507c on a P320 with a CHPWS adapter plate?

The CHPWS website product page shows 6-40x.38 FH T10 screws for Holosun. However when I received my plate, it came with 2 pairs of screws. The first pair are stainless color, T10 head, and are .46" long. The second pair are black color, T8 head, and .31" long.

I e-mailed CHPWS and asked to be sent the Holosun screws, and they sent me a new package with the exact same 2 pairs of screws.

The Holosun itself comes with two sets of screws, one set is T8 head and are .38" long. The other set are much shorter (maybe half as long), I didn't open or measure them.

I have read somewhere that the torque for the screws should be around 10 in-lbs. However it took significantly more than this to torque the screws in the threading, and when I hit 20 in-lbs the site was still fully loose and clearly not all the way in with a visible gap. I'm also concerned about damaing the extractor spring. So what the heck screws am I supposed to use?
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It has been a long time since I installed a 507C on my P320 so I can't give you feedback on the exact screw you need.

I can say that once you've decided upon which screws then...

Mount the plate with the extractor assembly removed.
Don't use any locktite; this is just a test fitting.

Then attempt to install the extractor assembly.
If there is any interference you are going to have to grind down the associated screw until there is no longer a problem.

I think I read somewhere on this forum that somebody received screws from CHPWS where one was shorter than the other.

Maybe they have finally fixed their little problem?
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If it’s an oem sig slide with their rmr mounting holes then It’s diff the 6-40 screws. The length is the issue. My C&H spacer only came with their stainless screws. Two sets one shorter then the other. I didn’t measure them. I used the shorter screws and did as stated above. I installed with the extractor removed and then shortened the screws. Both screws had to be shortened a bit.
remove the slide from the pistol. remove the barrel, recoil spring assembly from the slide. using the linked parts drawing for index numbers:

depress the extractor spring pin (10) and pop off the the rear slide cap (11).
remove the extractor spring pin (10), the extractor spring (9), the extractor pin (8), and let the extractor (7) drop out the side.

if you hold the slide up to the light, you can now see daylight through the extractor spring channel.
mount your optic using the correct thread-size screws, e.g. #6-40. hold the slide up to the light and observe any screw thread intrusion into the channel. trim the screw length until there's no further intrusion into the extractor spring channel.
test fit the extractor pin, spring and spring pin just to make sure there's no interference or binding with the optic mounting screw. if there's any drag, trim the screw another thread.

when the extractor spring pin assembly moves freely in the channel, then you're set as far as optic, right-hand screw length is concerned.

reassemble. use a thread-locking compound on the 2 optics screws.

not rocket science.

Sig Sauer P320
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I had to file the screw down on the extractor side quite a bit, as it was too long.

Sent from my SM-P610 using Tapatalk
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not rocket science.
For those who have been around the game for awhile and familiar handguns in general and with the P320 platform in particular...not that big a deal, we are used to dealing with this ****.

But for the newbie with their first handgun and trying to get in the game with a RDS...
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