The latest evidence is from an internal memo obtained by the anti-Hamas Palestine Press Agency that apparently shows a Hamas police directive to find rocket launchers and stop all rocket attacks against Israel, saying it is a severe violation of the law:
GANSO reports that Hamas police did discover and stop one rocket attack, on February 10th, from central Gaza. None of the recent rocket attacks have been claimed by Hamas.
One interesting incident mentioned in that same report occurred last month, when a test rocket was fired out to sea on February 8th. It is unclear if that was Hamas or another group. But it is possible that they were testing out a newer Grad rocket, as the rocket that hit Beersheba might have been a new rocket that was manufactured in China.
Is it plausible that the smaller Salafist groups or Islamic Jihad are importing longer-range Grads? Even if so, Hamas is certainly aware of it.