Picatinny Riser

For an M4/Ar-15 rifle, is there a picatinny riser that converts to a weaver rail?

I want to buy a Bushmaster .223 M4 Carbine rifle. The rifle has a picatinny rail above the receiver, which is what I want, but I found a red dot sight that I really like and it is for a weaver rail. Is there a short length riser, and about 1/2 an inch high, that will fit the picatinny on the gun and also have the weaver style rail for the sight on top? In other words, is there a riser with picatinny fittings on bottom and weaver fittings on top?
Please no “M4s and ARs suck, AKs are much better, .223s are for pussies, blah blah blah” answers. Yes, AKs are awesome too, ok?

The only difference between the Picatinny rail and the Weaver rail is the size of these slots, although many rail-grabber-mounted accessories can be used on either type of rail. Weaver rails have a slot width of 0.180 in (4.572 mm), but are not necessarily consistent in the spacing of slot centers. The Picatinny locking slot width is 0.206 in (5.232 mm) and the spacing of slot centers is 0.394 in (10.008 mm). Weaver devices will fit on Picatinny rails, but Picatinny devices will not always fit on Weaver rails.

But I think something like a universal laser, etc,, with only one screw to go through slot, would fit on either.

Milsig Paintball Standard Scope Riser Rail Weaver/Picatinny Mount Review by HustlePaintball.com