Registered Sear This tiny little piece of metal is a registered full-auto sear for the H&K series of firearms. It’s registered with the ATF to accept 9mm, 5.56x45/.223 and 7.62x51/.308; essentially it’s a drop in piece for a majority of H&K’s long guns. That multi-caliber aspect is what makes this valuable. What’s the going price on this? Expect to pay $10,000 to $15,000 just for this thing. Serial number is blurred. I’m not going to explain the whole aspect behind registered sears. I suggest getting your info from the ATF directly.