Navy SEALS with S&W Model 19?
Naval Investigative Service used 4" model 19's.
They were round butt, with yellow front sight inserts. They still have a few. Most were transferred to the FBI vault.
As has been mentioned already, the SEAL teams used 66's and 686's. Hope this helps. Regards 18DAI.
On page 186 of the 3rd Edition of the Standard Catalog Of Smith&Wesson, a Model 19 Variation named the ONI issue is listed.
In the year 1965, 1000 .357 Magnum revolvers were manufactured and issued to the Office Of Naval Intelligence (ONI) and the FBI, within the serial number range of K544000 through K624000. Specs: blue finish, 4" barrel, round butt frame, service trigger, standard hammer, red ramp front and white outline rear sights, grip adapter, and stamped "ONI" on the left side of the frame.
In 1966, Naval Investigative Service (NSI) was formed as a new separate agency, an off-shoot of ONI. NSI Special Agents were issued 200 Model 19 revolvers, similar to the ONI 1000, except with yellow front sight inserts, smooth combat triggers, and NSI markings rather than ONI. In 1972, about 450 of the 1200 guns, variously marked ONI and NIS, were transferred to the FBI. NIS and FBI kept some of them in service until the late 1990's.
(Elsewhere on the internet, I have seen, so far, unsubstantiated reports of 150 S&W Model 19-2 ordered by and issued to the Navy SEALS in 1965.)