Red Dot Sights

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Just finished reading an article in American Handgunner Magazine (Nov Dec 2024 issue page 20) about Red/Green dot sights. Author is Massas Ayoob and he relates that Police trainer Jeff Chudwin told him they are now offering a Duty Handgun Optics Armorers class for Officers who have gone to dot sights. Mount of Optics is the focus. Why? In the past year 50 to 100% failed in some fashion during their classes. Loose screws, broken screws, wrong screws, no or wrong Locktite,  etc. They recommend McMaster Carr in Illinois who carries the best steel alloy screw they can. They now check every firearm before moving to the range. 

Have any of you red dot sight guys had anything like this to happen? These guys are firing 100's of rounds weekly.

Me, I am not going to dot sights. My concern, if it is mechanical in any way, it can and very well may fail. Irons can break, but that is what I am putting my trust in. You are welcomed to your opinion's guys. 

[deerslayer]

I have played with various dots on several platforms and the only mounts that haven't failed me one way or another are Staccato with a Dawson plate and Glock with a C&H Precision plate.  I would feel confident carrying either one of these.  I've used Leupold, Trijicon, and Holosun dots and I feel more confident in the Holosuns.  

[ken_mays]

Yes, I've done a fair of optic mount work in the last 2 years.  Extracting broken screws from slides, replacing screws, drilling and tapping holes for bigger screws, fixing bad optic plate mount jobs,  sourcing replacement screws.

Some guns seem to be more prone to problems.  I had a rash of Prodigy mount issues there for a while.  The 6-48 screws Springfield provided to attach their plate to the slide are too short and if not 100% properly torqued and glued, they'll loosen.   Longer screws, extra torque and sufficient thread locker fixes it.  

I've pulled several broken screws out of Caniks.  They tend to use M3-.5 screws for mounting to the slide, which is about the teeniest screw you'll find.  Were it me, I would retap to a 8-40.

Other issues are due to improper pocket cuts.  One CZ owner had his Shadow milled for an optic but whoever did it neglected to leave a rear "shelf" which would backstop any rearward movement.   The second time his plate and optic combo loosened up, I retapped the holes to 8-40 and added a second set, so he now has 4 screws holding his plate to the slide.   No more problems.

I have several optics mounted to pistols of my own and haven't seen issues on them except (of course) the Prodigy. 

[Thearmededucator]

Going with a MOS plate is a big contributor for this. Too many failure points. It’s why I wend with the ACRO, its mounting system is basically a picatinny rail like we’ve been doing on rifles for 2 decades now. I trust it more. 

[deerslayer]

7 hours ago, Thearmededucator said:

Going with a MOS plate is a big contributor for this. Too many failure points. It’s why I wend with the ACRO, its mounting system is basically a picatinny rail like we’ve been doing on rifles for 2 decades now. I trust it more. 

The MOS cut on a Glock slide is good; the MOS plates Glock includes with each gun are crap.

[Thearmededucator]

13 minutes ago, deerslayer said:

The MOS cut on a Glock slide is good; the MOS plates Glock includes with each gun are crap.

Even good slides have twice the number of screws facing sheer forces. The design of the RMR footprint doesn’t help 

[toby1304]

I was running the time for a guy running a red dot once. We were on the third stage of the match and he was engaging an array of targets when he stopped and grabbed his eye. I took his pistol and we thought he had a ricochet until we realized his optic came off. Sliced his forehead, would have been his eye if he hadn't been wearing safety glasses.

[deerslayer]

1 hour ago, Thearmededucator said:

Even good slides have twice the number of screws facing sheer forces. 

Truth. 

[krunchnik]

My Sig P365XL sheared off 2 screws holding a Holosun 507K-

Looking thru the sight one minute and picking it up off the cement the next-

Cause I think was I torqued the screws too tightly-

[leroy]

Some things to think about from an old structural engineer who used to spend his time n make money designing connections in structures...

1.  The slide cut must be good and provide a shelf at both the front and back of the slide cut to help transfer the recoil forces from the slide to the optic.  Snug is your friend here... Sloppy cuts are not.  The snugness here allows for a bearing surface between your optic base and the shelf of the cut.  It decreases the " shear " load on the mounting screws.  I would also consider using some blue thread locker at the cut-optic base interface to help with locking the optic into the cut.. 

2.   The size and strength of your fasteners must be a known quantity.  I would buy " real " screws for this and ensure they were guaranteed as to size n specification. I wouldn't trust a bunch of screws packed with an Amazon Chinese no name optic..

3.  Install and torque the screws to the required torque with an appropriate torque tool... Not a guess, not a feeling.

4.   Common sense.  These screws are tiny, and you can, Indeed, break em in assembly by over tightening em... Just don't. 

5.   I would clean the screw threads ( both holes n screws ) with alcohol to remove any oils n apply purple screwlocker.  Ya can break it loose if ya need to.

food for thought .

Engineer leroy... Now retired...

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They recommend McMaster Carr in Illinois who carries the best steel alloy screw they can.

[deerslayer]

6 hours ago, leroy said:

3.  Install and torque the screws to the required torque with an appropriate torque tool... Not a guess, not a feeling.

4.   Common sense.  These screws are tiny, and you can, Indeed, break em in assembly by over tightening em... Just don't. 

We have a not-too-mechanically-inclined local guy who recently sheared his dot screws.  We asked how much he had torqued them.  He told us that he puts the screw in snug, then goes another half turn because that's rule of thumb.  He was dead serious.  After the roar of laughter finally ended, we told him he probably went from 20 inch pounds to 220 and that the hex or Torx screw head is probably round.  

[leroy]

44 minutes ago, deerslayer said:

We have a not-too-mechanically-inclined local guy who recently sheared his dot screws.  We asked how much he had torqued them.  He told us that he puts the screw in snug, then goes another half turn because that's rule of thumb.  He was dead serious.  After the roar of laughter finally ended, we told him he probably went from 20 inch pounds to 220 and that the hex or Torx screw head is probably round.  

HEHEHE... We used that " rule of thumb " in the old days to torque high strength bridge bolts...  ASTM A325 N ASTM A 490s.  They were at least 7/8 diameter.  The extra half turn stretched the bolts .  

I wouldn't apply this " rule " to small stuff...

leroy . 

[deerslayer]

36 minutes ago, leroy said:

HEHEHE... We used that " rule of thumb " in the old days to torque high strength bridge bolts...  ASTM A325 N ASTM A 490s.  They were at least 7/8 diameter.  The extra half turn stretched the bolts .  

I wouldn't apply this " rule " to small stuff...

leroy . 

Brigdes...makes sense.

4-40 X .345 dot screw...not so much. 

[peejman]

Search Google for fastenal torque chart.

#6 screws are 4-6 in-lbs.  #8 are 11-13 in-lbs.  The typical in-lb torque wrench won't be super accurate that low. 

And speaking of torque wrenches.... always, always, always store your twist-set torque wrench on zero.  They will drift significantly when left set to a torque. 

The comments about the slide cut are accurate.... if you don't have to tap the plate in place, or put it in the freezer, it's not tight enough.