Sheep Breeding

I have a breeding question about a ewe that we have.

Ram A   +  Ewe B
 \              /
      Ewe C    +   Ram R
      \              /
          Ewe J      +    Ram X
           \               /
               Ewe M

Can we breed Ewe M to Ram A?  It would be her Great Grandfather, but wondering if we have enough other genetics mixed in to make it okay.

Thanks for you help!!

there are a few online Coefficient on Inbreeding COI calculators online:
http://www.babydollsheepregistry.org/calculator.htm
here for example. You have to say what is ok for you, If I remember well sheep usually have a COI of 10%

PS: this article on inbreeding might be interesting for you
http://www.nabssar.org/asc223_sheep_inbreeding.pdf

This is great! Thank you so much! It is much appreciated!