Jim Yachinich explained this to me in detail and I have posted it below. It’s a lengthy explanation, but I think you’ll be happy to get all the details. Here it is:
I would group your TMR with the GM1025 and GM1026 together and all three will basically make the same measurement as a 48” ruler. Their measurements are taken the same way as the 48” ruler. None of them will measure putters correctly. The MA1000 and MA2010 measure the same way but it is a different measurement in that it measures down through the center line of the hosel compared to the other gauges measuring against the back of the hosel. These two units will also measure putters correctly. If you measured a driver at 45” on your TMR and then measured it on the MA1000 or MA2010 it will measure 45.5”. An iron that measures 37” on the TMR will measure 37.25” on these two units. We show this measurement difference on our Standard Length Chart. https://www.golfworks.com/images/art/StdLengths.pdf
I always say that if I am going to measure a club correctly for length I would first set it up in a Golf Club Gauge, like the GW1040, for the correct lie angle and then measure length from this position. When I do this the measurement matches up the measurements from the MA1000 and MA2010. However that being said I would say that the majority of club manufactures are using the measurements that come from the TMR, GM1025 and GM1026. When the USGA references the 48” length measured at 60 degree lie angle the measurement is taken the same way as the TMR, GM1025 and GM1026.
In his last book Ralph referenced the differences in these measurements and the one thing he said is that whichever way you measure stay consistent. Personally with my own clubs I still use a 48” ruler that I have had for 30 plus years. In the school I always use the MA2010 and of all these measuring devises it is the one I would buy if I decided to change away from my 48” ruler. The sole plate can be adjusted for lie and it will correctly measures all sole designs. It measures putters correctly. I can measure all the clubs, drivers, fairway woods, hybrid, irons, putters with this one gauge. With the TMR, GM1025 & GM1026 I need another gauge to correctly measure putters.