  We discuss an alternative for Baryon-violating six quarks transitions, in the
contest of low scale string theory. In particular, with $M_{S}=10\div 10^{3}\rm
TeV$, such a transition can be mediated by two color-triplets,through a quartic
coupling with down-quarks,generated by exotic instantons, in a calculable and
controllable way. We show how FCNCs limits on color-triplet massare well
compatible with $n-\bar{n}$ oscillation ones. If a $n-\bar{n}$ transition were
found, this would be an indirect hint for our model.
  This would strongly motivate researches of direct channels in proton-proton
colliders. In fact, our model can be directly tested in a experimentally
challenging $100\div 1000\, \rm TeV$ proton-proton collider, searching for our
desired color-triplet states and an evidence for exotic instantons resonances,
in addition to stringy Regge resonances, anomalous $Z'$-bosons and gauged
megaxion. In particular, our scenario can be related to the $750\, \rm GeV$
diphoton hint identifying it with the gauged megaxion dual to the $B$-field. On
the other hand, this scenario is compatible with TeV-ish color triplets visible
at LHC and with $1\div 10\, \rm TeV$- string scale, {\it i.e} stringy
resonances at LHC.
