POI Shift wanneer geweer val

[Geno]

Ek het die interressante stukkie raakgelees op FB. Ek gaan van nou af sommer al my monterings se skroewe lube wanneer ek hul opsit.

A very good post by Hakan Sphur on another group

A few years ago after reports of POI shift on a gun after it fell over while resting on its bipod I did a lot of testing to determine the cause of this and how to resolve it.

I did both tests on the range and in the workshop, where I would smack the scope with an open hand - roughly the amount of force you would use to start a bar fight. Most of my testing was done in a milling machine where I mounted two vices, one with a collimator and one with a heavy duty picatinny rail.

I tested a lot of mounts, or more or less all the important mounts on the market at the time and the results were pretty clear:

If the surface betwen the picatinny rail is dry when the mount or rings are installed, the best mounts and rings would have 0.4-0.5 mil shift in the direction of the smack. The worse mounts and rings had 2-3 mils total shift.

Everything was checked with a dial indicator to see where the movement was occurring. And the movement was betwen the mount and the rail.

When lubricant was added, the better mounts and rings in the test such as ours and Badger USMC rings had less than 0.1 mil movement.

Why?
Its rather simple. If a screw is torqued dry about 95% of the torque is lost in friction. If lubed the result is way better, but still the majority is lost in friction.

So a dry mount against dry rail means that the mount hangs on friction. When a scope or a gun takes a hit, the mount can shift, but with a quality mount and a lubed rail the issue disappears.

Loctite:
I haven’t tried to loctite betwen picrail and mount, but i have tried to loctite betwen TRG rail and mount and that gave less good results than oil!

I encourage everyone to zero your gun and start smacking your scopes, and don’t forget to post the results here!

[Rudiejacobs]

Ja, want as jy nie jou geweer ren minste 2 keer op jag trip laat val nie, was dit nie n goeie trip nie.

Laat my nogal aan Arno se video dink, die man het toe dalk n punt beet gehad.

Rudie.

Sent from my LG-X230 using Tapatalk

[Smitstertjies]

So dip jy sommer net jou skroef in geweerolie voor jy ringe vasmaak?

[Wouter Roets]

More Martin

Soos ek verstaan uit die skrywe gaan jy al die oppervlaktes wat in aanraking is met mekaar moet smeer om enige spanning wat daar heers te neutraliseer.

Groetnis
Wout

[Geno]

Ek verstaan dit soos Wouter.
Lube die rail se oppervlak wat kontak maak met die ringe, en die ringe se oppervlak wat kontak maak met die rail.
Dan ook die skroewe om seker te maak hulle torque glad.

[tau]

Ek het die interressante stukkie raakgelees op FB. Ek gaan van nou af sommer al my monterings se skroewe lube wanneer ek hul opsit.

Why?
Its rather simple. If a screw is torqued dry about 95% of the torque is lost in friction. If lubed the result is way better, but still the majority is lost in friction.

Waar kry die man dat 95% van krag gaan in friction in?

Ek dink dit is bietjie rof.

Skoon gesnyde draad en fisies skoon draad kontak area gaan mos ook mooi loop.

[Philip_R]

Ek het nou in 'n ou handboek gaan oplees oor die, basies moet 'n skroefdraad altyd gesmeer word om seker te maak dit torque reg en dat die krag wat die koneksie in plek moet hou groot genoeg is en wrywing nie die aksiale spanning in die boud/skroef verlaag omdat die skroefdraad byt voor dit moet nie.

Dit maak egter gladnie sin om die rail self te smeer nie, maar die rail se skroewe kan gesmeer word voor dit vasgedraai word. Mens wil nie 'n gesmeerde oppervlak tussen 2 stukke materiaal hê wat mens juis wil hê moet in plek bly nie.

So smeer die skroefdraad maar nie die rail nie sou my voorstel wees.

[Apie]

Smeer soos in olie/Ghries of Copper slip?

Lyk my soos ‘n rondgooi toets vir Piet Skiet!


Sent from my iPhone using Tapatalk

[Philip_R]

Mens olie of ghries iets wat gesmeer moet bly en heeltyd kan beweeg, copperslip is gemaak vir skroefdraad, gebruik eerder dit wat vir die doel gemaak is.

[Capt. Yoda]

Smeer soos in olie/Ghries of Copper slip?

Lyk my soos ‘n rondgooi toets vir Piet Skiet!


Sent from my iPhone using Tapatalk

Ek dink as jy jou gun heeltyd laat val gaan dit nie saak maak of jy hom met snot of gouglip lube nie