No. Thus the covering of IRAN in detail.
Over time two kinds of improvements are made: correcting a flawed design and implementing an improved one. Not really the same thing. So let's take them individually:
1) Flawed design. "The gas tank straps on the F-150 fail. Recall them and replace them. All of them." If the flaw is less serious you can use the "replace them during overhaul and throw them." So a design flaw that is serious enough where you want to eliminate the old part.
2) Improved design. "While the trigger design was good one of the designers has developed an improved one. New manufacture going forward will use the new but the old design, being adequate, will not be discarded; even during an overhaul."
Adding a slit to the barrel band is a very minor improvement. There wouldn't be much value to recalling or even discarding them during the overhaul process. So new rifles would get them during manufacture but during IRAN the old would be reused with new only being used to replace non-recoverable ones. Thus in 1903 rifles coming out of SA, new, would have the slit band but the bulk of the rifles coming out of rebuild at RIA would have the old. I say the "bulk" as rifles, when issued, are not normally turned in for overhaul within a year or two and thus the rifles going through RIA in 1903 would not typically included 1902 production (only been in the hands of the troops for a year or less) or 1901 production. A rifle popping out of IRAN with a non-slit band in 1903 wouldn't be unusual. With the obvious exception of the 1892s as the old bands were made for stocks having the channel whereas the rebuilt and replacement stocks had it filled. Which, if you think about it, means that slit band helps date when an 1892 underwent conversion to 1896 format. Assuming it wasn't sent through IRAN after conversion and issue. Which most were not.
I have a cartridge belt from 1918 and one from 1941. The one from 1918 has a modification made from 1942 forward whereas the one from 1941 does not.
Towards the end of M1 rifle production rifles were noted to have a strange inclusion of "WW2" parts. Burning up stocks of NOS parts that had been replaced with improved designs but were from #2 above.
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I'm going to make an observation about how a Krag is approached vis-a-vis the detail parts. People tend to assume, via hope, that every gun skipped IRAN. Then parts are examined looking for signs of rebuild. Reverse that. Assume it went through IRAN. Your review will be much faster. So pick up a Krag and immediately look at the cartouche. If it's not crisp you can pretty much stop right there. If it is crisp you can keep looking. I'd also observe that examining detail parts has, for ages, given people the false assumption that the gun is original as people really didn't think CPSD through. If your rifle was issued and turned in with 700 others they were likely made about the same time. Issued to your unit at the same time. Turned in at the same time. Went through IRAN at the same time. Thus the parts flowing through IRAN are from 700 rifles all very close in production. They'd all get a part swapped if #1 above was in force but, if not, they would not. So if 80% of the parts survive IRAN that means many pop out with all the parts being from the right production time-frame. Doesn't mean the rifle is "as made" obviously. So look at the cartouche. Those were sanded to recover stocks. If it was lightly used in service it'll fool you but for most it'll be sanded a might heavier.