Probably going to run a T-1 for now, mounted low to co-witness with the irons. I'm looking for an IBSZ-type zero distance for M80 Ball that, like the 5.56mm IBSZ, gives a good "flat" trajectory for a reasonable distance without holdovers.

16" barrel, so I'd imagine M80 Ball running in the vicinity of 2500fps +/- and I think the height-over-bore is around 2.5".