The center label didn't really change in 1950, but the text under the label did (see below), as did the look of the word "Powerized," which now featured flatter lightning bolts.

Models numbers were stamped into the knob.

The barrel stamping was unchanged, with "GENUINE" above the player's name and "LOUISVILLE SLUGGER" below.

"REG. U.S. PAT. OFF." replaced "Trade Mark Reg." under the center label in 1950.

Note that the "R" in "Reg." is aligned under the "OU" in "Louisville" and that the second "F" in "OFF." is aligned under the "K" in "KY."

In 1961, the wording under the center label became more condensed. Note that the "R" in "Reg." now is aligned directly under the "U" in "Louisville" and that the second "F" in "OFF." now is aligned under the comma.

Another slight change is that the "2" in "125" now is aligned directly above the "&". Before 1961, the "2" was aligned between the "&" and the "B" in "BRADSBY" (see above).

Everything else looked the same as in 1960.

At some point in 1964, the text under the center label was eliminated in favor of a ® following the word "SLUGGER" inside the oval. A new version of "Powerized" also appeared, sans the looping "d."

However, some bats were made that combined the new version of "Powerized" with the old text under the center label. This occured in 1964 only.

Another variation featured the old version of "Powerized" with the looping "d" combined with the new center label that featured the ® after "SLUGGER" and no text under the oval. It's generally accepted this variation began in 1964 and continued through 1966.

I have a bat with this combination that matches factory records from 1966 (and no other date).

The combination of the new version of "Powerized" and the new center label -- with the ® after "SLUGGER" and no text under the oval -- began in 1965.

Model numbers still were stamped into the knob, and the barrel markings remained consistent with prior years.

Many collectors combine this label period with the previous one, categorizing bats as being from the 1965-1972 era. However, there is one slight difference that differentiates the periods.

Beginning in 1969, the "P" in "Powerized" changed on some bats. Instead of the bottom loop of the "P" stopping at the downstroke, it crossed the line just a bit.

In 1973, the version of "Powerized" used from 1965-1968 returned (note the bottom loop of the "P" stops flush with the downstroke).

The easiest way to identify a bat from this era is the ® that began appearing above the "ed" in "Powerized."

If a bat has the model number stamped into the knob and has the ® above "Powerized," it must date to this period.

This label period is maybe the easiest to identify of any because H&B replaced "Powerized" with a special logo commemorating America's Bicentennial.

However, there was another key change as H&B stopped stamping model numbers into the knob. Beginning in 1976, model numbers appeared on the barrel, above the player's name and right of the word "GENUINE."

In 1977 (perhaps even sometime during the 1976 season), "Powerized" returned.

1979 was the last year for the traditional Hillerich & Bradsby center label. If a bat has this center label, combined with "Powerized" and the model number on the barrel, it must be from this label period.