Whoever told you that is on crack!
Here is the list for Glocks. 17, 19, 20, 21, 21SF, 22, 23, 26, 27, 29, 30, 31, 32, 33, 36, 37, 38, 39
Also approved are variants with original Glock barrels which are longer than standard (e.g. 17A, 17DK), as well as variants with "Tactical", "Mariner" or similar OFM engravings on the slide, provided the barrel length does not exceed 127mm, and provided all other aspects of these variants fully comply with all other Production Division rules.
Not Approved:
18, 24, 25, 28, 34, 35, Pro, L and C models
Also here is a link to the Ipsc list.http://www.ipsc.org/rules/proddiv.php
Glocks are great but if you want to be competitive in Production division I highly recommend you llok at buying a CZ SP-01 Shadow... you will not be disappointed. Glad to see you getting into the sport That is awesome!