Ho-103 synchronized rate of fire

Hi gents!

According to The Pacific War Online Encyclopedia, when synchronized Ho-103 rate of fire slowed down to 400 rounds per minute. Same is stated by same entry of Wikipedia.

Since in a well known study by Richard Dunn are mentioned initial problems with this weapon ("The early versions of the 12.7mm Ho-103 were simply not reliable and were subject to jamming"), I wonder if also slow synchronized rate of fire was later (and when) overcome, reaching higher values (and which).

Thanks for any help,
GB

For a high synchronized rate of fire, the time interval between the pilot ( or the interrupter gear) pulling the trigger and the shot being actually fired has to be as short as possible. The Ho-103 was a Browning derivative and as such fired from an open bolt, meaning that the bolt had to run forward and lock before the round was fired. Most other aircraft machine guns fired from a closed bolt so the shot went off at once. I don't think it was possible to decrease the mechanical inertia of the Browning mechanism enough to get a significantly higher ROF while synchronized. Almost all British or US aircraft used Brownings unsynchronized (outside the propeller disc(s) ) for that reason

Thanks, mike (I think once is enough!) for your clear answer. Nevertheless, I'm puzzled, since I read in the past about Lewis (firing as well from an open bolt) that it was impossible to get synchronized. Also, Wikipedia states the M2 fired from a closed bolt...