I attended the SHOT Show this year and spoke to Hal at the ATK booth. These are the folks that design and manufacture ammunition for law enforcement and the military.

As I walked up to the booth I started to speak with another Rep and asked about whether they were ever going to sell #1 buck in the FCW shell. He said that they were not, as far as he knew.

Then Hal walked up and said, "Didn't you and I talk about this last year?" I said that we had. He then said, "Well, I just learned that we are indeed going to produce a #1 buckshot load with the Flight Control Wad. We didn't think there would be a market for it, but we've had a lot of requests, so we are going to make some and see how it sells."

I told him, "There can't be a market if there is no product available." He grinned and said, "That's what I told them. I guess we will both see."

So keep your eyes peeled. We are finally going to get the best buckshot in the best wad.

Nope, but he indicated that they were "ready" to start.  No date given.

Currently, only #4 buck sometimes fails to meet the 12 inch penetration standard.  Any buckshot larger than #4 will meet it.

From the Shotgun Ammo FAQs:

"Number 1 buck is the smallest diameter shot that reliably and consistently penetrates more than 12 inches of standard ordnance gelatin when fired at typical shotgun engagement distances. A standard 2 ¾-inch 12 gauge shotshell contains 16 pellets of #1 buck. The total combined cross sectional area of the 16 pellets is 1.13 square inches. Compared to the total combined cross sectional area of the nine pellets in a standard #00 (double-aught) buck shotshell (0.77 square inches), the # 1 buck shotshell has the capacity to produce over 30 percent more potentially effective wound trauma.

In all shotshell loads, number 1 buckshot produces more potentially effective wound trauma than either #00 or #000 buck. In addition, number 1 buck is less likely to over-penetrate and exit an attacker's body.

For home defense applications a standard velocity 2 ¾-inch #1 buck shotshell (16 pellet payload) from Federal, Remington or Winchester is your best choice. We feel the Federal Classic 2 ¾-inch #1 buck load (F127) is slightly better than the same loads offered by Remington and Winchester. The Federal shotshell uses both a plastic shot cup and granulated plastic shot buffer to minimize post-ignition pellet deformation, whereas the Remington and Winchester loads do not.

Second best choice is Winchester's 2 ¾-inch Magnum #1 buck shotshell, which is loaded with 20 pieces of copper-plated, buffered, hardened lead #1 buckshot. For those of you who are concerned about a tight shot pattern, this shotshell will probably give you the best patterning results in number 1 buck. This load may not be a good choice for those who are recoil sensitive.

While #1 buck might be ideal IF the the shot is hardened, the reality is that these loads might be hard to find. If finding hardened #1 proves elusive, 00 buck is a great choice instead."

Sorry.  Don't know what that is.

Okay.  No, sorry, didn't ask.

You might find this helpful:  Shotgun Ammo FAQs