Dave, great information! Now I'm wondering when the "no-fire" order was issued. I believe B-29s claimed about 20 or so MiG-15s but were these kills before this order?
B-29's were credited with 27 MiG-15's in Korea. All were credited in daylight, before the B-29's switched over exclusively to night operations in areas with serious MiG risk which happened at the end of October 1951 after some heavy losses; of course the don't shoot first tactic applied to night operations only. Once the switchover was ordered, FEAF bombcom scrambled to equip all B-29's with SHORAN radio navigation gear which previously only a few in each of the three groups had (after 1950: 19th 98th and 307th BG's). With SHORAN, bombers flew in stream (at night) along an arc of equal distance from one SHORAN transmitter, releasing bombs when the bomber reached the correct intersection of that arc and another arc from a second transmitter. CEP's with this form of bombing were eventually reduced to under 1000', with goals of around 400' expressed, not much if any worse than was feasible in daylight.
Analysis of B-29 credits v Soviet accounts of each combat shows that probably only 3-4 MiG's were downed altogether by B-29's. However one certain Soviet loss was in a night attack, not credited to the B-29 in question (though it did fire after being fired on, and claimed a possible kill), in August 1952. I don't know when exactly the tactic was adopted not to fire unless fired upon, perhaps after the first outright losses of B-29's to MiG-15 night fighters in June 1952 (though as covered in a previous thread, La-11's managed to damage a couple of B-29's in December '51). After the first losses to night MiG's a number of improved defensive measures were introduced, including ordering flash hiders for the guns. The most obvious measure, from photo's, was painting the bottoms of all a/c black. The Soviet nightfighters relied on searchlights (in the style of German WWII 'wild boar' tactics) except in very favorable weather and moonlight. The black bottoms substantially increased the difficultly for s/l operators to hold the B-29 in the 'cone', even after searchlight radars told them the relatively narrow arc to scan (FEAF ran trials with B-29's with and without bottom camo v US air defence s/l's over Japan to test this). ECM against the s/l radars, and fighter ground control radars, was another key measure. A difficulty there though was that LeMay of SAC insisted no post-WWII ECM gear be used in Korea, lest it either fall into enemy hands or even just its use revealed its capabilities.
B-29's in Korea had no tail radar. Many were refitted with B-50 type tail turrets in night phase, and as of late 1952 FEAF Bombcom planned to add post-WWII type tail radars, but it was not done before the armistice AFAIK (and most B-29's went to the boneyard in 1954). The B-29's could sometimes detect nightfighters with their APQ-13 bombing radars, although that wasn't the designed purpose of that equipment.
RB-50G electronic recon a/c were operated by the 91st Strategic Recon Sdn based in Japan, over Korea and throughout the Far East, starting in August 1952. The initial detachment consisted 3 a/c, 47-149, 47-151 and 47-161. None were lost in the Korean War proper, but 47-154 was shot down by MiG-15's two days after the Korean armistice near Vladivostok, July 29, 1953. It was speculated that it was in retaliation for the US downing of an Il-12 on the last day of the war that the Soviets claimed was a civilian airliner not over Korea. In general the 91st SRS and predecessor unit weren't only at risk over Korea during the Korean War. The first victory by the Soviet MiG's deployed to Korea was against an RB-29 Nov 9 1950 over NK, and another was downed in January '53 (on a mission over NK, per its original mission report, though the Chinese claimed it fell just inside China and held the surviving crew two years past the Korean armistice). However the unit lost two other RB-29's during the war, outside Korea: 44-61810 July 4 '52 to MiG's and 44-61813 to La-11's that October 7, both near Soviet Far East territory, to fighter units the Soviets didn't consider deployed to Korea.
Sources for all of above (besides the easily Google-able) are FEAF files. Bud Farrell's "No Sweat" is indeed a fine book (and he's a nice guy). Another first hander is "B-29 Navigator" by Ralph Livengood. He flew in daylight period in '51 as opposed to Farrell's experience in night missions in '52, so good balance between those two.
Joe