35 sucks but it's AVAILABLE and BD really is economical. Cool, fast bullets. LGS's here are still naked of anything but bullets.
As for AR, I don't think it's possible unless you totally alter the gas system and/or bolt carrier. I tried BD loads in my VM15 and nope, no cycle, and these were firm loads in my bolter. I suspect either the port has to be moved back, or you need to totally "swiss cheeze" the carrier because you are NOT going to get more gas at the right time at the right place in the barrel. BD loads do their work early, which is why the muzzle report is so relatively quiet compared to full-house "real" loads. What makes BD work is, the curve of the pressure is shaped so there's a smooth, high push without spikes, and that curve is affected by overall pressure. There's a sweet spot there, nobody really knows WHY it's there, but it exists and is special.
I have considered buying a carrier and finding a lighter spring to see if it's possible because it would be fun if it worked. But I know you can't make it work by tweaking the load. Good BD loads are "real" loads and you can't ignore physics.
One suggestion, something I've asked Seafire about, is Lil Gun under lightweights in 223. LG is fabulous in the Fireball, makes it act like a 223 in the 40 grain class. "Book" under 40s for Fireball is about 16, I run 15.5. I've THOUGHT about trying 15.5 of LG as a starting number in 223 and working up on a chronograph, but with components so ridiculously scarce, I'm focused on just enjoying the pet loads I already have.
