Chinese cast cash - real or fake?

Hi
I have two Chinese cash coins, which I bought in Beijing
.
Are they real or fake?
The reverses are blank (I could upload pictures), they are non-magnetic, and weigh 4.0 and 3.4 grams.
Thanks

Neither?

That's a tough question. The 大 on the right coin looks a little strange. Currently I would say that they are not real and that they are modern counterfeits cause the 元 on the bottom left is too perfect for the Song Dynasty era, but I can't guarantee it.

I have two friends who might be able to help.

Thanks