74g
I peeled the backer off and the backer weighed 48g. The problem with that was that the glue between the backer and the CF is not affected by lacquer thinner, acetone, purple degreaser, or turpentine. I rattle can painted the glue and it makes it not sticky, but the sticky is still there just under the paint so if you scratch it it's there again.
I made a comment about this on Accurate Shooter and Mark said he can make them without the backer if you want. I My F-TR rifles run very close to he weight limits, (I run heavy barrels) so I can't spare the weight.