Optic cut thread wears off possibility?

[zzero000]

Just install a new red dot for my vp9 or last weekend.
Unfortunately, the red dot and the plate fly off on about 25rd.
I thought the 3/8 screws were too short caused the plate to fly off, and bought some 1/2 screws.
I found out I could never tighten them when they reach at the end.
Also I found one the screw is wiggling inside of the hole.
Is that mean the threads on the slide wear off?


Video link.

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[Flopsweat]

Looks like the metal the screws were made of is harder than the metal the slide was made of. A gunsmith can do a few things to address that. If it were me, I would drill out the holes and tap them. They will take bigger screws now, which could be confusing to the next person to work on the gun, but the modification would cost me nothing as I have a tap & die set.

I don't believe the warrantee would cover the repairs, but I haven't dealt with H&K.

 

[VinnieBoomBah]

Sounds to me like you have the wrong size screw

 

[Koda]

Also I found one the screw is wiggling inside of the hole.
Is that mean the threads on the slide wear off?

Unfortunately yes. Do the correct screws fit and tighten?

I dont understand buying new/different screws than using what the manufacturer provides or suggests. If the plate flew off with the correct screws were they properly torqued with blue loctite? What torque amount does the owners manual say to use?

 

[VinnieBoomBah]

If the slide is so soft that the weight of a red dot could strip all the threaded holes at the exact same time it would be beaten to a pulp by the slide railes and locking lug.

Also, explain to me how a 3/8" screw can strip threads 1/2" deep.

Take you time. I'll wait

 

[Koda]

If it were me, I would drill out the holes and tap them.

depends on how bad the situations is. Before I would retap larger I would try to chase the existing threads with a forming tap of the correct size.

Im also not clear on if he actually stripped the threads or just bought the wrong size longer screw that wiggles.

 

[zzero000]

Unfortunately yes. Do the correct screws fit and tighten?

I dont understand buying new/different screws than using what the manufacturer provides or suggests. If the plate flew off with the correct screws were they properly torqued with blue loctite? What torque amount does the owners manual say to use?

It feels tighten during the process. But whenever it reach to the very bottom, it become like that.

The plate I bought does not come with the screws. So I used whatever the red dot provided on the plate. The Hk stock cover plate's screws were rounded on my last removal.

 

[zzero000]

If the slide is so soft that the weight of a red dot could strip all the threaded holes at the exact same time it would be beaten to a pulp by the slide railes and locking lug.

Also, explain to me how a 3/8" screw can strip threads 1/2" deep.

Take you time. I'll wait

By that I mean then length of the screws.
One of the left is the new ones, the one on the right is the one cause the fly off.

 

[Flopsweat]

Are the threads stripped on the slide? I probably should have asked that first.

 

[Koda]

It feels tighten during the process. But whenever it reach to the very bottom, it become like that.

The plate I bought does not come with the screws. So I used whatever the red dot provided on the plate. The Hk stock cover plate's screws were rounded on my last removal.

What size is the correct threads? What is the correct torque needed?

If your rounding screws your doing something wrong. This isnt a 'hand tightening' project, you need a small torque wrench for pistol red dots.

 

[DirectDrive]

You need :
1) Correct thread pitch and screw size
2) Correct length
3) Loctite (use blue)
4) Torque screwdriver (know correct torque)

You need to hit all the above items to do this right

 

[zzero000]

Are the threads stripped on the slide? I probably should have asked that first.

Hi, yes it is. it is the stock optic ready mode. I had a hard time getting the plate off after last use.

 

[zzero000]

Hi guys
Got all sort it out. turns out I bought the imperial unit size screw which is 0.5mm smaller than the HK's metric screw.
Thank you all for helping the noob.

 

[Oro]

Hi guys
Got all sort it out. turns out I bought the imperial unit size screw which is 0.5mm smaller than the HK's metric screw.
Thank you all for helping the noob.

I just saw this thread and I see there was some good advice.

For you, I suggest the next time something like this comes up, go to Westlake Ace Hardware (since you are in Bellevue). They have die templates where you can test your screw/bolt/nut sizes and huge bins of the correct imperial and metric hardware. Technically they are in Kirkland but like by 100 yards.

https://www.acehardware.com/store-d...ocal&utm_campaign=localmaps&utm_content=17918

Ask them for help and they will give it, good place. I used to live in Redmond and when I needed exact hardware this is where I went as Home Depot, etc. are no use.

 

[DirectDrive]

Hi guys
Got all sort it out. turns out I bought the imperial unit size screw which is 0.5mm smaller than the HK's metric screw.
Thank you all for helping the noob.

Study up.
You want your guns to live in a good home.

 

[PiratePast40]

I went to red Locktite on my M&P to keep the optic screws from loosening. If I need to ever take them out, I can use a soldering iron to heat up the screw.

 

[DirectDrive]

I went to red Locktite on my M&P to keep the optic screws from loosening. If I need to ever take them out, I can use a soldering iron to heat up the screw.

I didn't recommend red Loctite for the new guy above just because he might need a do-over and Red would introduce another problem.