The basic facts are.... the nominal weight of the bullet is 160 grains.... but due to manufacturing tolerance it could have weighed 159.5
Or it could have weighed 161.5 grains, like one weighed by Robert Frazier.
CE399 obviously lost some weight in the barrel of the rifle..... which would put it's weight at approximately 159.6 at the muzzle.....CE 399 weighed 158.6
Any weight lost in the barrel would be negligible.
Which leaves only one (1) grain for the fragments..... and the fragment in Connally's leg was probably heavier than 1 grain....
From the WC testimony of Dr. Shires:
Mr. SPECTER - What would your best estimate be as to the size of that fragment?
Dr. SHIRES - One millimeter in diameter---one to two.
Mr. SPECTER - Would you have any estimate as to how much that might weigh in grains?
Dr. SHIRES - In grains---a fraction of a grain, maybe, a tenth of a grain---very small.
Mr. SPECTER - A tenth of one grain?
Dr. SHIRES - Yes.
Dr. Gregory, in looking at the X-Ray of the thigh, said that the fragment was about 5 tenths of a millimeter by 2 millimeters. At those dimensions, the lead fragment would weigh 17.8 milligrams. One grain is equivalent to 64.8 milligrams. So, that fragment weighed about 1/4 of a grain.