If you find a source let me know, as I have been looking for the exact same thing for some time. I have called several reputable dealers and finally Beretta themselves and this is what I have been told. The ASE-90 was built for the 1990 olympics and was largely hand done- so much so that it is considered to be a box lock version of the SO series of shotguns, which is Berettas premium line. They came with a spare set of dropout triggers as well. Supposedly a few thousand ASEs were found after the ASE Gold has come out and Beretta took them, and engraved them in an English scroll style and sold them as premium shotguns. The cost was high for Beretta to produce, so they then built the ASE Gold which is nearly the same gun but only came with one trigger. Many of the ASEs were made with Boehler Antinit barrels though not all. To further cut cost, the ASE was replaced by the DT10. The DT10L and EELL hand more hand chased engraving, or sideplates, upgraded wood, and some parts were hand polished. They were created in the “Due” factory where the SO series are made. The standard DT10 was not. Now the DT11 has replaced the DT10 and even more of it is created by CNC machining. It has a wider action but uses the same trigger group as that of the DT10. From what I have been told, the ASEs are interchangeable but the barrels and triggers will not interchange with any DT shotguns. The barrels of the DT10 will not interchange with the DT11 but the triggers will. If any of this information is incorrect someone please let me know. I don’t own ASEs or DT11s but had researched all I could when looking for a competition shotgun recently. This information is based on my conversations with Beretta, Cole Gun, and Joel Etchen as well some gun owner who had ASEs.
