1 Longshot,
Hard to say what diameter they are. It all depends on what dia. they drop from the mold and what sizing die diameter he uses. I have the RCBS 150FN mold and it works just fine in my Marlin's micro-grooved bore.
At 15-16 b.h.n. you should be able to get to at least 1,800 f.p.s. with good accuracy if the bullet fits the bore. Try putting the nose of the bullet into the muzzle... any resistance? If so, good, as long as it will chamber. If not, accuracy will not be as good as it could be.
A DuPont powder phamplet of several years ago shows a load of IMR4831 at 36 grs. giving 1,898 f.p.s. with only 30,100 CUP. The .30-30 is rated for 38,000 CUP, so your load is plenty safe.
NoBade,
According to Brophy's book, .30-30 Micro-grooved bore diameters prior to 1968 tended to run as large as .304".
After 1968 the number of grooves decreased from 16 to 12 and the bore diameters were held closer to .300".
My 336A Marlin was made in 1978 and has a .300 bore and .307" groove and shoots cast bullets extremely well ... up to 2,400 f.p.s.
Perhaps later production had a tendency toward larger bores again(?).
w30wcf