Robert Bryant's recent post says: that gammas are not emitted appears to be the approximate reality in experiments.
The most logical explanation from studying nuclear physics would be to assume that some of the energy produced by the third d+d fusion branch is transferred by electrons emitted from internal conversion and pair production. In addition, the third d+d fusion may have a low cross section, as indicated in an earlier post. The possibility of internal conversion and pair production doesn't seem to have been discussed previously by cold fusion scientists. Instead, researchers devoted significant time and resources developing alternative theories to explain the reason gamma radiation is not detected.
The idea of varying the amounts of deuterium and hydrogen should help in understanding cold fusion, as gamma radiation would be expected from p+d fusion.