05-27-2011, 06:41 PM
JASmith Wrote:I was just looking at one of M. Fackler's reports, and it looks like the 7.62 bullet was not the M80, but a 150 gr FMJ...It doesn't seem to make a difference if it's a 147gr FMJ. Attached shows "copper" (actually gilding metal) jacket M80, with same wound profile.
Quote:I think you see the reason for delayed onset of tumble in the boattail designs is the same for why Tony has been suggesting a hollow windscreen. The boattail moves center of gravity forward, which helps stability. We want to move it backward...The 5.45x39 M74 bullet also appears to have a rather large-caliber ogive. Perhaps that is another factor effecting early yaw?
Quote:The good news is that there may be some clues in the BT/non-BT results to give us a clue on how far it needs to move and whether the void can be filled with something visible to x-ray but otherwise low density.Why fill the void? Any substance will necessarily have much higher density than air.
Again, why bother trying to reinvent what has been shown to work? Just scale up the 5.45 bullet to 6.5mm and be done...