In Texas deferred adjudication is a problem for getting one's CHL (we don't have OC here so that point is moot, but if they DID have OC here, it probably still would apply).
Texas has 14 "disqualifiers" (that's a lot, and there WERE 15: Owing any school loans was finally dropped) for getting one's CHL -- here is disqualifier # 2:
A Texas Concealed Handgun License may be issued to any person who:
2. Has not been convicted of a felony, including a deferred adjudication.
Maybe other states follow this but of course, you'd need to check YOUR state of residence.
Still, D-A DOES seem to be a common problem...especially for someone who did something LONG ago (YEARS), never went further in the court system afterwards and went straight (no more legal trouble) since that time.