Actually the GOOD bendy beam type as shown in Muskys photo can be calibrated by moving the click trigger in or out
I had mine tested while back when I got the 36" Britool one as he was mobile & had a call out fee of $ 90 + $10 for each additional wrench
They were all within 2%
I bought most before I was 20 and they get used by me & have been loand out hundreds of times
Admittedly the spring loaded wrences have a finner adjustment but to a large extent, unless you are right on the strength limits, consistency is more important than precise accuracy
Bolt a head down with 10 sets of bolts from 10 different companies & you will have 10 different clamping forces
That is the nature of threads
Add to that each & every time a bolt is torqued into a hole, the thread on the hole wears so the exact same amount of torque will yield a different clamping force .
And then we have the "clean dry" thread which only exists for the first tensioning .
