Certainly. Lots of pictures coming, but I'll say from the start the single biggest difference in size, beyond barrel and slide lengths, is the front-to-back measurement of the grip frame, and therefore the magazine well. A standard 1911 magazine will not fit in the EMP well. The EMP magazine will slide into the 1911 well, but doesn't fit in the correct sense.
First, the barrels. There are some very small differences in the diameters of the barrels along the chamber, and of course the EMP4 has an integral ramp, where the full size 1911 has the ramp in the frame. The EMP4 in these pictures is my 9mm version, the 1911 is my SA 1911A1 in .45 Auto. Top picture is the 1911, bottom is the EMP4
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I measured from the breech face to the front of the forward locking lug in these two. Top is the 1911, bottom is the EMP4:
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Now, the frames. The EMP4 slide fits the 1911 frame and will slide all the way back. The 1911 slide will fit on the EMP4 frame, but is stopped by the EMP4's ejector, which is thicker than the 1911's and won't fit in the slot in the slide. So, the frames are the same width and the slides are the same width. Don't give me any grief about the idiot mark on the 1911 frame, I bought the gun used and it already had it.
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Height of the frame from the slide rail to the bottom of the grip is the same on both guns. Angle of the grips to the frames are identical, as you'd expect. When placed butt-to-butt, you can see the difference from front to back of the grip frames. 1911 is on the left, EMP4 on the right.
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Next is looking down on the frames. EMP4 is on the left, note how the ejector extends over the mag well, where the 1911 on the right has the extractor flush with the rear of the well, and of course the 1911's well is deeper front to back.
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Now, frames top-to-top, note the distance from the rear to the trigger guard is the same, and the EMP4's ejector is longer (left):
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Last shot shows the guide rods and springs. The EMP4 uses a long guide rod and has no barrel bushing. There is a small hole in the guide rod, when you pull the slide back for disassembly, you put a small bent pin (a paper clip works great but a "tool" is included with the pistol) into the hole and it traps the spring compressed within the internal rod bushing, making take-down easy. The barrel on the EMP4 slides out the front, just like the 1911. When I reassembled the pistols after making the pictures, I used the slide stop from each gun on the other gun. They are identical, fit perfectly in either gun and both guns function with the other's slide stop/takedown pin.
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