From Hakan Spuhr:
There is a discussion about quick change LOP on chassis and as much as that was primary feature when I started design of spuhr chassi we was not first!
First was as far as I know the TRG folder, and I have been using both variations of TRG folder for 15 years because of the feature and I really like it!
But, as it’s two pins sliding in two holes there is a risk that when change LOP under stress that it get stuck. There is also a play in the system so you never have the feeling that its really solid.
Solution is as said very good But I wanted more and I also wanted travellimiters so I can preset the min and Max LOP i want.
After TRG it took many years before American Rifle Xylo and Jet chassi hit the market.
Both of them are sort of quick adjustable, and espesially the Xylo.
What is always problematic design wise is linear movement, linear movement sucks and should be avoided if possible.
Now a LOP adjustment is likely kinda difficult to make rotary so it gotta be a linear movement.
The issue with linear movements is there is amazing possibilitys to gather dirt and stop the movement.
Typical solutions is to have loads of play, and allow the dirt, such is the TRG designed.
Another solution is nearly no play and that way stopping dirt from coming in there.
Another issue with the LOP adjustment is tolerances, if aluminium is used surfacetreatment like anodizing have a splendid way of ####ing up tolerances.
Spuhr LOP solution is a mix, when LOP adjustment is moved there is plenty of play and loads of dirt or sand can be there without function is an issue.
But when it locks it locks on conical selflocking surfaces and there is zero play, and will always be zero play.
Great for speed adjustment, great for issues in production and dead lacked while locked.
As far as I know there is no one else using a similar solution.
Our LOP adjustment is maximum 50mm movement, but can be Limited to for example +20 to +40mm. That gives a LOP adjustment of 20mm and its extremely fast as it goes betwen two end stops.