I've never shared the same fascination with the different 416 gas blocks for short barrels. I sold my 416 upper as soon as the MR556 came out, cut the MR to 11.625", and found it ran great with the stock 16" gas block with several combinations of buffers and springs in addition to the stock ones. Later, I found my 10.4" MR556 also ran fine with the stock 16" gas block. I figured, that last thing I'd want is the 10.4" unvented gas block and was pleasantly surprised when HK later came to the same realization and vented the 10.4". That said, I don't see the fascination with them either as I figure mine is overgassed anyway when suppressed and using the 16" gas block. Finally, I have a gas block to be excited about both unsuppressed and suppressed, see pic. Hoping for the best.