Stripping stones from asphalt

Hi all
Does anyone know a better way to remove the stones and chippings from an asphalt roof??
We got job to prepare and bitumen prime an asphalt roof ready for a felt overlay but the problem is the roof is 40m2 with these chippings on, we have removed and bagged the loose and then started to scrape the ones that were stuck using shovels/scrappers etc ( we did the scrapping for around 3 hours and did not get very far). This method seems the only way to do this but is very time consuming and extremley difficult.
Does anyone have any other suggestions or helpful tips which would make it a bit quicker?
Thanks in advance
Goon

Heating them up with a Gas Gun would help but it is a messy job .

DAZB said:

Heating them up with a Gas Gun would help but it is a messy job .

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No, it won't.

Get down HSS and hire a scarifier for the day. 40m2 will take about 2 hours.

Thanks for the replies.

i think i'll go to the hire shop and try one or those scarifiers, cheers Xenon.