I'd say you're doing it wrong if you end up reaming out the gauge.
Kind of my thinking too. I've used sets like these for many years with no "reaming".
https://www.kittstools.com/product4148.html
I suggest getting a set of calipers. Learning to measure drills bits with calipers gives you the ability to measure anything up to the capacity of the calipers (0-6” typically) and if you get digital calipers, you can switch to metric should you need to go there. Combined with a drill chart, you’ll have everything you need glowing forward. You might even be able to buy a cheap set of digital calipers in the $20-$30 range.
I have calipers and mikes and know on how to use them. Their precision isn't needed to measure a bolt. Example, dirty SAE bolt won't fit in 3/8" hole, but fits in next size up hole. It is a 3/8" bolt. I do know that in some special situation, there could be some odd OEM special bolt and thread but not worried about that special case.
I have calipers and mikes and know on how to use them. Their precision isn't needed to measure a bolt. Example, dirty SAE bolt won't fit in 3/8" hole, but fits in next size up hole. It is a 3/8" bolt. I do know that in some special situation, there could be some odd OEM special bolt and thread but not worried about that special case.
John just curious but do you often use your drill gauge to size threaded fasteners? I have always found those plastic/nylon nut and bolt gauges handier for things like that. I keep one in my tool drawer at all times. The drill index I generally just keep with my drills and taps
I use it all of the time. If it fits, why not use it? I only have the one gauge and have used it for everything. I want another because I am lazy. Say one is at the tool box with drills and taps, it would be nice to have one at the work bench to measure the bolt.
Last week I needed to build another drill bit set out of the many drill bits I have. Pick a bit, put it in the gauge, get the size and then stick it in a standing drill bit gauge/ stand as a double check and place to put the bits. I built an almost complete set very fast.
Need to measure a dowel pin, just stick it in and done. Unknown tap, take a quick measure and good to go. I think I even measured brake line tubing once.
A lot of things I measure, close enough is more than ok. It doesn't matter if a 3/8 bolt is .374".
Now that I think of it, I also wouldn't mind a gauge 1/2" to 1". I know it would be easier to measure a 3/4" bolt with a gauge than a tape measure even though it only take a second.
SAE sizing is usually is fairly easy for me

I bought a couple of those bolt/screw gauges from Brownells, the firearm supplies vendor, for identifying small SAE vs metric threaded screws and bolts.
I discovered that some metric bolts will screw into SAE holes, and vice versa, because these "gauges" are so thin that the threads on some screws will have only a single thread in the gauge. Similar thread pitches will cause an SAE screw to mimic a metric screw, and vice versa.
So, if you have these gauges, beware you don't make a trip down to the local hardware store to buy screws mis-identified by these too thin "gauges".
I posted last week on this topic. One of the responses recommended Starrett but at $85, it is too much for me. Can someone recommend one that is ok for bolts and drill bits, won't ream out with just a few uses say up to $20?
PEC blem from eBay or Epstein’s.
Jeff