I had a fitting done by Griffin & Howe using their try-gun followed by patterning. At the end of the fitting session I had the fitter measure my Merkel 1620 and let me know how far off the gun was from my custom dimensions.
Next, I determined how far off from my needed dimensions the 1620 was by patterning the gun. I then compared the results of the two different measurement methods. The amount of stock adjustment needed to make the 1620 fit as determined by the fitter and by patterning the gun were the same. I sent the gun off to be bent and the gun shoots very well for me.
I then had a CSMC RBL 20ga made to the G&H dimensions. I wasn't sure how well the G&H dimensions would work with the RBL 20ga because the RBL clearly has a thicker butt than the 1620, but I had never heard that custom dimensions determined by a fitter were gun-specific so I went ahead. Shooting the patterning board shows the completed RBL 20ga to shoot 6" to the left at 20 yds. The thicker butt had indeed required at least a new cast-off dimension. In hindsight I thought to myself "well duh."
I now determine gun fit by shooting the patterning board. This is done with each specific gun I regularly shoot. Where the gun actually prints determines how much stock adjustment is needed. This method automatically accounts for any dimensional idosyncrasies (known or otherwise) a particular gun may have. Plus, it is very easy to do. Verifying the gun "shoots where I look" is a great boost to my confidence in the firearm. The G&H measurements go unused in my desk.
The custom fitting by G&H was a worthwhile experience (don't get me started on my experience with their bending service, though) because it caused me to start paying attention to gun fit and gave me a baseline to start working from. IMHO, however, dimensions from a fitting session are gun-dependent, and will almost always require some amount of fine tuning from one specific gun to another. This leads to the problem of paying for the expense of a custom stock when using dimensions from a previous fitting session which will be only "close" rather than "spot on." I guess "close" is better than "not even close," though, and "close" is good enough for someone who's mount is not consistent. Further, everyone has their own idea of what is "good enough." In other words, YMMV.
In light of my experience, so far, I would not pay to have another fitting done - shooting the patterning board is just too easy and is the final arbiter anyway. The only exception would be if the fitting was by a stockmaker making a stock for me, which would be the ideal situation.
JMHO.
--shinbone
