During the 60's, 70's and 80's, the government did alot of testing with "heavy" 5.56 loadings. Federal, Colt, IVI and others provided 68 and 77grn FMJ's, some with AP capability. The testing seemed to be extremely promising, especially in relation to M193, SS109, M80 and M118 loads. Accuracy, trajectory, wind drift and penetration all seemed to be excellent.
I have some documentation from Aberdeen and Rock Island that seems to suggest the Federal 69grn AP FMJ was the superior 5.56 load.
What do you guys think of these heavy FMJ's? Their performance against NATO plates/helmets was equal to or better than the SS109, depending on the loads anyhow.
How do you guys think these would do against intermediate barriers? Seems like a non-fragmenting 77grn FMJ would do alright through some barriers, depending on its design. Design might also allow it to yaw very early or not at all. Again, design could also make it fragment violently.
Whats the general consensus about these rounds? Opinions or thoughts?
That is intresting and I have heard it before.
I like 68 grain alot in match loads.
1. Different weight bullets function differently in different actions/lengths/twists/barrels.
2. More weight leads to more energy, more speed leads to more energy, but since during the flight path of a single bullet one unit is inversely proportionate to the other, the answer is to match the physical characteristics of the round to the desired planned application. There are certain rounds out there that are better matched for more broad-ranged application (applications that may require a number of different goals). Those rounds are already in use. There is no magic bullet though.
Personally I believe 55g bullets are too light for broad applications. I also believe that FMJ bullets are not a good design for broad applications. The current 77 grain load is a black hills load that uses Sierra match king bullets (the 77 grained bullet). The effectiveness on game with those bullets has been proven to be questionable, but since all is fair in love and war they have been used to kill men and they will if used appropriately. I have used that same black hills load in a 600y match and I can tell you with 100% confidence that they will do their job if you do yours, but I do not believe 5.56 is an appropriate round of which to use as the basis for broad ranged applications. Others out there that have shared my thoughts have been experimenting with other rounds throughout the years which have led to the 6.8spc, 6.5 Grendel and 6.5MPC to mention only a few.
Penetration of barriers...Now here's a thought for you to contemplate: A .22 rimfire round shot from a 5" barreled pistol will fully penetrate a U.S. legal tender quarter at 12 yards, but a .45 ACP will not. A .45ACP bullet will fully penetrate a 4x4 treated post, but the .22 rimfire round will not. Why?