I lucked out. I think I bought 8 of these and the only one that was iffy I knew it was, It had a non issue R stock so worth it, sold off the rest)
One I got simply because it had a red band and while the pictures were awful, it looked ok. Sold that one to a guy who wanted a Danish return which it was and was in nice condition.
But you do take your chances. One went back when he guaranteed it would pass with least a 2 reading the rest was hacked. TE was 5. I got a bit of guff but as he ran on Gun Broker all I had to do was threaten to bring them in and he backed down.
Steven Mathews makes a TE MW gague that he calls hobby type but is more than good enough for professional let alone hobby or low level collector.
Its not specifically calibrated to the 1917, but he said it was close and my observations on far more than 8 guns says yes.
The bigger issue to check is Throat Erosion.