"Things I have learned--as mentioned, this block does need to be solid and well mounted (again remember, NOT because of energy from the firing mechanism), but rather because once you add a stock--you end up applying force at the far end of the stock, which translates to higher forces at the fulcrum."
"My biggest concern with these designs is that when a stock is put on and if there is upward force on it, then the area around the screw holes will have a leveraging force around it which risks cracking. It would be nice to have a third point near the bottom which fastens the mount to reduce the force. I don’t see how to easily do this without modification to the gun. The nice part about your design is that if the block does crack around the screw holes, the offset screws still hold the metal back in place."
It's been interesting following your (
@Navig) project. I wish I had the skills, and equipment to undertake such projects. In lieu of this, I'm at the mercy of procuring manufactured parts from others. Which is a bit of a leap of faith that the design will work out and be long lasting and durable.
Unfortunately, I'm concerned, from an "
anecdotal" observations, that my recent Buck-Rail grip & pic rail conversion, "
may" not entirely possess the structural integrity at the spot where a shoulder stock is mounted onto the pic rail. Just as you two indicate, regarding the structural integrity from mounting a stock onto the pic rail block. The design of the Buck-Rail pic rail section, based on my observation after mounting my stock, is in essence free floating and "not" secured to the rear body of the GK1. Of which, presents some torsional and bending forces at the base of the pic rails' connection with the main body of the grip mod (see attached image). Pic #1: using a light under this section, illustrates the gap between the rail & GK1 body without any loading of the stock. The red circle and white arrows denotes where a potential weak point is on the rail, and thereby, with any movement of the rail, appears to stress. And I "surmise", this "
may" be where it "
potentially" fails - due to a "fulcrum" or "leveraging force" as @Navig.&
@TiPascal so apropo theorize. Pic #2: under mild pulling of the stock, you can see that the space in the gap has at least doubled.
Again, please note, I am not a structural engineer and merely expressing my observational hypothesis. I abhor mentioning any negative commentary about the Buck-Rail grip accoutrements. For the 3D print quality is one of the finest I've seen and laid hands on. I also need to mention their customer service is excellent; and hopeful that any potential subsequent iterations, will address any "potential" structural design defects. The "one off" design and material that
@sb327 (Dave) used in his grip mod, IMHO is the way to go and will most likely last the test of time!
In the meantime, I own it and will continue to use it. But feel as if I have to always be cognizant of the amount of torsional movement it exhibits each time I deploy the folding stock during use. Not a fully comfortable position to be in. I equate this to the issue we have with the V1 & V2 mag release lever, that requires us to always remember to gingerly close it to avoid snapping it off, whilst under higher pressure levels.
In closing, I believe this would not be a problem, if made out of a durable metal. Or in the least, if the rail sat flush with the rear of the GK1 body AND not be free floating, but secured with the two bolts already located on the rear of the GK1 body. Other than all that, I'm very happy with the Midwest Industries shoulder stock and all its ability to adjust the LOP, cheek riser and shoulder pad!
