Same, except I use Goo Off. Wife’s not a big nail polish girl, so don’t have any NP remover in the house.Originally Posted by Utm
Same, except I use Goo Off. Wife’s not a big nail polish girl, so don’t have any NP remover in the house.
Where do you get screws for that price?
I just ordered a set of Torx screws for an SRO from Jagerworks and it was $7/pair!
Turn the screws counter-clockwise.
The major problem with screws in pistol mounted optics is shear force since the slide is reciprocating with a high amount of lateral force, potentially against the fastener (screw).
Ultimately, there are to my knowledge three forces acting on a fastener. The most common in terms of listing of screw/fastener strength is tensile, which are the forces acting parallel to the length of the screw. This includes the two parts being attached pulling apart, as well as a screw that’s being tightened against two parts.
Shear force is roughly, depending on the formula used, around 57-58% of tensile strength. It’s related but not the same. I’m no engineer and there are people on this forum who can explain this much better than me, but in the case of pistol optics, you’re going to see shear failure well before tensile failure unless you’re torquing at a crazy amount.
The third force is torsional, and that’s where one can shear a screw on installation. I know less about torsional force than I do about tensile or shear, and that’s not saying much, but suffice to say that if you’re putting too much torque into a screw to where you go beyond the elastic deformation range of the material and enter plastic deformation (where the metal moves and can’t return to it’s previous state/position) then the strength of the screw is now seriously compromised if it doesn’t break altogether.
That said, torsional impacts dissipate quickly once the force is no longer applied so as long as it’s not “too much”, it won’t get “worse”. Tensile forces are minimal in pistol optics since the primary force of slide reciprocation is horizontal. Shear forces are the main culprit, and those affect the screw and not the threaded holes in the slide. If one is damaging the slide they are seriously messing up optic installation protocols.
If I’m wrong please let me know... Engineering means math and I’m a deputy so my college math experience is “math for non-majors”.
What pistol/plate are you attaching the SRO to?
Most of what I use comes from McMaster-Carr and for Trijicon stuff it’s pretty much all high-strength alloy steel. It just depends on the length dimension for the specific pistol. I only have information for a small selection of pistols that my department approves, but if it matches what you use I can get you the order number from McMaster. They don’t pay me but at this point they damn well should.
I went back and looked at the pictures I have when we tested the Trijicon SRO. It wasn’t realistic since we fired almost two thousand rounds in less than a half an hour, but the movement of the markings was very small. It was way less then an 1/8th of a turn. The optic was shooting well off point of aim and the screw sheared as soon as I attempted to remove it.
I then spent way too much of my life going through a crap ton of pictures and found that when our T&E Leupold DeltaPoint Pro came loose on our S&W M&P 2.0 OR pistol it was a super minimal amount - well less than with the SRO. In this case, we had no torque spec and we were experimenting to determine what would work without being too much. In this particular case with factory S&W hardware 12 in/lbs was too little. We also found what was too much, which I think was around 20 in/lbs when the hex drive stripped. We later determined based on our “experiments” exactly what S&W engineers confirmed, which is 15 in/lbs. We didn’t abuse the pistol/optic with the DPP like we did with the SRO so there’s that too.
I’ve seen a lot of optics come loose, and most of them were perceptible if there were indicator markings. The fact is though that almost all of them were “felt” before they were seen, and the marking deviation was minimal. I have on numerous witnessed occasions walked up to people in class, asked them to hold their pistol on target, wiggled the optic, and then had them come off the line to get it re-mounted. The witness marks are almost always “not perfect” but “not horrible”.
Ultimately, the indicator marks are an “early warning” against complete shear failure, and by the time any movement is perceptible stuff’s gone wrong and the optic needs a complete re-mount. The screws are potentially (probably) structurally impacted and the gun is likely if not definitely not shooting to point of aim any more.
@SoCalDep that’s great data and thanks for educating us as always! I love this place and really appreciate you taking the time to tell us what you know and why you know it!
Ah, yeah, I was FoS on that, you are exactly right...
I think my thoughts jumped to general experience with hex and torx capscrews, seems like the sockets hold up well enough to GET them too tight, but then are loose when you are trying to get the suckers out. But at the ~15ip for an RDO that shouldn't be the issue. But those screws are hammered with shear force twice for every shot.
Figure that they are charging you $7 to pay somebody to take them out of the McMaster box and put two of them in a ziplock, $7 is really more of a handling charge.
Here is the link to McMaster, and Trijicon says they ship the SRO with 1/2" long flat heads:
If you have the ones you just got from Jagerwerks (or the old ones) and can measure them, just know that flatheads are the whole screw, not to the shoulder:
Also, if you live in a town where there are any factories Fastenal is another option, and they probably have something like that on the shelf or if you ship to the store I do not believe there is any shipping charges.
Yup, for sure. There is a ton of knowledge here that you can trust.
I just shoot a lot and they seem to fall off on their own... Is that not working for you?
http://instagram.com/p/CTK9Gvmn1xS/
SRO to factory Dawson plate on Staccato P.
According to the insert that came with all the optic stuff. The screws are 6-32 x 7/16 FHC screws for the SRO to plate. Plate to slide is m4-0.7 x 4mm LHC screws.
Reply With Quote