62 gr TBBC LE223T3 and XM556FBIT3 are still available and widely used--both significantly outperform Mk318.
My issue was with accuracy. XM556FBIT3 shot worse than MK318 for me. Also, the exposed lead tip, I believe you said a while back that this caused reliability issues in a few hundred rounds. MK318 doesn't have that draw-back.
The original Federal 77 gr TOTM developed for the USMC in 2006 was essentially a bonded SOST. It is an OUTSTANDING performing load as shown on pg. 12 of this briefing:
http://www.dtic.mil/ndia/2008Intl/Roberts.pdf. It was not adopted by the military for very stupid reasons that had nothing to do with JAG or the Hague--more like bureaucratic ineptitude and ignorant requirements documents--you can't make this unbelievably incompetent shit up...
I don't know the reasons...but it was invented. It was created. Someone, somewhere, has some. Someone tooled up and made some. They CAN be had. I just don't have the relationships forged to have them. I hope someone who does makes it happen. Group buy?
After the USMC dropped the ball on TOTM, Crane took the design and ran with it, issuing the non-bonded Mk318 and Mk319. If military end-users could enlighten their requirements folks, there is NO reason a bonded SOST version could not still be adopted.