Using iptables, set up NAT for a specific range on a local bridge

I'm trying to get a NAT setup for a specific range of IP addresses. I run a QEMU/KVM hypervisor with a local bridge that has ip range 10.0.0.0/8. On that bridge, I have several IP ranges for different machine classes. A couple of those ranges are used to provide exteal IP adresses to the VMs via 1-to-1 NAT. This works perfectly.

Now, I want to set up a range of IP addresses for machines that get inteet access via regular NAT (think consumer router). The IP range is 10.0.0.5-10.0.0.150. After searching online, I tried to add a rule like:

iptables -t nat -m iprange -A PREROUTING -i eth0 --dst-range 10.0.0.5-10.0.0.150 -j MASQUERADE

iptables isn't set up to block any traffic. Still, the NAT isn't working. My VM can ping the hypervisor, but can't ping any hosts on the Inteet. IP packet forwarding is enabled.

Any ideas?