I was looking for the 152mm ammunition of the T-14 for quite a while and finally found at least a dummy round which gives a good impression of the overall size.
Means the complete round seems to be about 1360mm long! And as we saw it from the 125mm it is separate loading as an auto loader hardly could handle such a long round.
Current T-14s in service (very few) are still equipped with the well known 125mm gun as the 152mm is still having bugs which is being worked on.
Anybody with better images?
Image source: internet.