Changing a new model TSW DAO (MIM parts) to TDA involves replacing the Firing Pin retainer with a manual safety assembly; the MIM DAO hammer & trigger with MIM TDA hammer & trigger; and replacing the DAO sear
(spacer) release lever (no lever 'foot' and it has 2 holes in upper lever) with a TDA sear release lever, which is a fitted part. (It has to be filed/fitted for the critical decocking timing to be within the proper spec in a TDA gun.)
A hard and fast rule is that the different generations of DAO parts must NOT be mixed, meaning not mixing MIM and Machined parts. A MIM DAO hammer (tub shaped indentation on spur)
must be installed with a MIM sear, and a Machined DAO hammer
must be installed with a DAO machined sear. If improperly mixed the contact area between the DAO hammer notch and sear nose
won't be correct.
The DAO/TDA triggers are different, as well.
The other 2 levers in the frame (ejector depressor and firing pin safety) are the same in both TDA/DAO models.
FWIW, the DAO assembly is different than the TDA guns when it comes to the disconnector's installation.
In the DAO guns the disconnector must be installed before the drawbar is installed and connected (pinned) to the trigger.
In the TDA guns the disconnector can be installed after the drawbar has been installed & pinned in the frame, by gently slipping/turning the disconnector's tail around the drawbar's disconnector tab (the little "ramp" on the front/middle of the rear of the drawbar tail).
However, this is where some inattentive armorers may rush things and exert too much pressure against the
plastic disconnector's tail (using a pin punch to push the tail to one side or the other, so it slips "above" the drawbar tab), and they may break the tail off the disconnector.
During one of my TDA/DAO armorer updates several years ago, the instructor said that while the new nylon disconnectors had been observed to be very durable and reliable in exhaustive factory R&D ... the main cause of damage to them was ... armorers.
I think I remember that instructor saying that factory endurance testing out past 25,000 rounds showed the nylon disconnectors lasted just as well as the steel ones.
It was mentioned in one update class that there was reportedly some ongoing discussion at the factory of whether to return to using steel disconnectors, but only because they were more resistant to
armorer-caused damage and breakage.
A couple of advantages of the nylon disconnectors are the more precise tolerances and the reduced friction (increased lubricity inherent in plastic-on-steel contact).
The older steel disconnectors
might (seldom, it was said) have a problem called long-tail disconnector, where the tail was too long (too thick/tall) to allow for proper disconnect. Not good., if it happened. It required very careful stoning/filing of the tail to put it in tolerance. That also meant that the opposite problem might occur because the armorer might over-file it, which could ruin the disconnector and cause a problem in safe functioning/disconnect. (Easier to try a different disconnector, though, and not worry about filing, as they were easy & inexpensive parts to keep on hand, for an armorer.)
The nylon disconnectors were uniformly precise in their tolerances. Once the nylon disconnector was designed and was being used, that problem/corrective action eventually disappeared from the newer armorer manuals, BTW. I once met an armorer instructor who had never heard of the disconnector long-tail problem, not having been part of the armorer pistol training program until after the newer guns had been in-service for several years and the manual no longer listed it in the trouble-shooting section.
The inherent "lubricity" of the nylon tail running on top of the drawbar's steel tab made for reduced friction, too. Smoother movement between the 2 parts.
This is just some off the top of my head thoughts, and it gets a bit more complicated when discussing the different revisions of the original 3rd gen DAO guns, as the frames were machined at different times for both 1 and 2 levers (and a spring) being on the right side of the frame in the older days. This info isn't meant to be a "how to" bit of commentary, but some info to show why it's really something that ought to be done by someone familiar with the 3rd gen guns of different vintage and action.
