Well I use the neighbors seed drill which puts on fertilizer, whatever seed grain mix you want for cover crop and sprinkles grass seed on top behind the seed/fertilizer discs. Pulling a Bear Cat sprocket packer behind the seed drill gives the grass seed about the right amount of cover. A good seed bed gives the best germination of your (pricey!) grass seed.
Last year we were very happy with our cover crop of a triple mix of oats, barley and peas at about 125 lb. /acre. The nice thing about that mix or any forage type mix is that you usually cut it early enough to get some really good growth out of your grass seed for the rest of the summer. But even though we cut and wrapped it at the dough stage last summer, it was so dry that the grass/alfalfa mix didn't get uniformly tall enough to take a "second cut".
The triple mix yields well too. Ours put up 10 1000 lb. (+/-) bales per acre. Wet weight, of course.
This spring that field looks fantastic. Think and very vigorous. So it works for us.
We put on about 18 lbs. of an 80/20 grass seed mix (alfalfa timothy) and I think every seed grew!