Chastise means to punish, as by beating or to CRITICIZE SEVERELY.
http://thesaurus.reference.com/browse/chastise
The meanings that you gave also is correct, but there is more then one meaning. Stating that Chad's work is only guessing, not only belittles all of the work he has done trying to record Rugers History, but is a severe criticism of his work. Anyone who writes about Ruger uses estimated numbers, unless they have factory records to look at, and even then they are sometimes wrong.
What you said was "Well, it seems to me that you are only guessing how many will be made. They do have a business schedule to follow. Maybe they are making what fits into their schedule right now. Maybe what they are making right now is profitable enough that they don't want to drop anything that is selling well for something new".
This implies that Chad's production numbers are usually fact and this time he is only guessing. Of course he was only guessing as Ruger nevers says how many of any model that they make. His numbers are always a guess. I don't understand what [Chad only guessing about the number of guns being made] has to do with the rest of your statement anyway. Whether Chad was guessing or not has nothing to do with your statement about Ruger's business schedule. Perhaps you added this to criticize that Chad was "only guessing", to imply that he should get the actual number? Maybe you put this in your statement to plant the seed that if he is only guessing then he could be wrong about his other statements. Ops! There I go putting words in your mouth again, but that's the way I read it. But as I said above. ALL PRODUCTION NUMBERS ARE GUESSED AT. Ruger never gives production totals. Anyone who reads the RENE would knows that. Every one that has read anything about Ruger knows this. I bet you knew that unless you don't read the RENE. So saying it is "only a guess" is a derogatory statement, meaning that he is only guessing so don't put too much stock in it. If you didn't know that when Chad gives a production figure for any gun it's a guess, then I am wrong. If this is the case then I apoligize for saying that you chatize Chad because not knowing this fact, you would be correct in adding this to the begining of your statement to chastise Chad for "only guessing", even though It is not germane to the rest of what you said.