I hear you Ron, GF1, and HOS concerning the designations for virtually the same model and there is no information to the sidelock design changes. RL Wilson's book was too broad on Beretta. He gave some of the basics on the SO-series. Other than people posting what they have and how the guns are marked the information does not appear to exist.
I've seen some guns advertised on gunbroker and gunsinternational stating the SO designations of EL and EELL weren't marked on 1950s guns. The guns are advertised as an S3EL or EELL, but clearly have S3 engraving (i.e., not full coverage and not as deeply engraved). I don't believe that is true based on your posts and other guns I've seen.
Beretta does not seem to have or easily provide information for these guns as other makers will provide. The NY Beretta Gallery was helpful but could only provide some limited information on the two S3EELLs I own. One gun is gamescene engraved by A. Baglioni and the other is the floral type engraving by S. Tononcelli. I also asked if Beretta kept something similar to a build sheet for the guns and they don't offer the service.
Response from NY Beretta Gallery:
I have received a reply regarding your inquiry. Both Mr. Stefano Tononcelli and Mr. Angelo Bagliono were members of A.I.A.B., which is an Association of Engravers from Brescia, Italy. Mr. Tononcelli was born 1925 and died 1969. Mr. Baglioni was born in 1899 and passed away in the early 80s. Both of these gentleman did outside work for Beretta. There is really no information written on either of the men specifically, but I have included some information about the association in the attachment.
Ken
