The SP5 along with the three-lug barrel is also threaded 1/2-28 RH for us US types to rock a thread on suppressor if we are not cool enough to own a tri-lug can yet. I think they call that the "C" barrel if I remember correctly.HK 94 was the 16" barrel rifle length version imported before the Bush Era import ban. The SP5 is imported as a pistol with a 8.9" barrel with the intent that the end user will likely put on a brace or SBR it. Basically the same firearm except the SP5 has the three lug barrel and paddle mag release.
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@trevi also the 94 has the SEF lower that usually only has the safety/selector on one side of the lower. The SP5 and SP5K have the newer "Navy" lower with the abi safety/selector and of course, the cooler bullet markings vrs just letters for FES.