Do you refer to the use of sintered projectiles with special materials carried in the porous metal? Interesting!
Below are images of the Oilite projectile as used by the Dairt reloads. Under magnification the features of the sintering process can be seen as Mel suggested. I think that there may be some smoothing of the external appearance when forming of the bullet’s shape happens. Note the conical recess in the base has the typical frosted look of the Oilite bearing. Still, the 147 gr. weight of this projectile is the big clue here as the loaded rounds feel strangely light.
While I think Ray may have been thinking of sintered iron projectiles when he started this, the topic is “Sintered Bullets”…
Any other Oilite ammunition out there?