Most AR15 lowers will accept all of the full-auto parts except the sear. The SP1 will not accept the sear, even if you drill a hole for the pin, A portion of the lower receiver would have to be milled out to install the auto-sear.
The SP1, however, will accept a DIAS with no modification, but I believe most lowers being made today would also accept the DIAS. This is why you cannot own an unregistered DIAS and an AR, or you may be in constructive possession of a machine gun.
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