Kragkid,
I have said much the same thing on other forums in answer to those who try to read in too much to SRS. We should be eternally grateful to Frank Mallory for all the hard work he did compliling this information. I always mention two reservations, however:
1) As you said, rifles were rarely shipped in "blocks". While rifle #300,000 might have seen service on San Juan Hill, rifle 300,001 might have been used to guard an Indian reservation in North Dakota.
2) Mallory's information takes only a "snapshot" of the firearm. There is no promise that the firearm stayed with that unit for any length of time.
I have collected a number of U.S. firearms over the years and have yet to find a "hit".
I DO appreciate all the work that went into the information gathered.