That would be an interesting creature! Those barrels vary quite a bit in diameter. I've seen them from .311 to .315. What kind of guage would you use? Unless you have something to guage the rifling depth, it would be almost useless in most .303s. There is just too much variation on calibers.
Well for the .30 Cal USGI rifles there is a guage that is tapered from 0.300, 0.301, 0.302, 0.303 to measure the muzzle wear of the rifling.
If there is no such thing for the .303 British rifles I guess I can adapt pin guages to do the job.
Should pin gauges from 0.303, 0.304, 0.305 and 0.306 do the job?
I'm not concerned with the depth of the rifling just how much erosion the rifling has gone thru from the original 0.303 bore that the factory made.
Any hooo I will order some pin gauges and let you guys know how it turns out.
I had read somewhere that Fulton was going to offer other guages but I do not know if its happened as yet. This would give you a minium bore diameter.
As far as wear is concerned, slugging with calculations based on the percentage of area of lands vs. grooves since the Enfield has an odd number of lands and grooves of unequal size would give you an "average" groove diameter as opposed to a rifle with an even number and equal size of lands and grooves which can be simply measured. Calculating is necessary as a slug cannot be accurately mic'd with the odd number scenarios. A difference of two slugs taken...one a muzzle and one farther back would yield any difference as to muzzle wear from cleaning. Since average groove diameters will vary as noted above, this comparison will tell for your rifle. See Hatcher for details.