P320 slide question- what are these “drill holes”?

What are these two holes on my P320 compact slide? When I line it up next to my subcompact slide, they don’t match, as the subcompact has a singular oval hole. What am I looking at?

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Phred

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I believe those are just there to reduce slide mass. They are “lightening” cuts, just not the latest cool guy windowed slide type.

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sigfreund

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I would be fascinated to learn the official explanation, but I have long assumed that that sort of machining on the inside of SIG pistol slides is to fine tune the weight of the slide.

The full size P320 slides for 9mm and 357/40 are significantly different on the underside. The 9mm slide has two deep holes and a long slot machined on one side, but the 357/40 slide has neither holes or slot.

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DirectDrive

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double

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DirectDrive

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quote:
Originally posted by DirectDrive:
quote:
Originally posted by sigfreund:
I would be fascinated to learn the official explanation, but I have long assumed that that sort of machining on the inside of SIG pistol slides is to fine tune the weight of the slide.

The full size P320 slides for 9mm and 357/40 are significantly different on the underside. The 9mm slide has two deep holes and a long slot machined on one side, but the 357/40 slide has neither holes or slot.

You just provided/reiterated the "official answer".

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BuddyChryst

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My understanding was SIG worked quite hard at figuring out the exact lightening cuts needed for each slide length/caliber in order to ensure that no matter what crazy loading someone decided to use, the pistol would properly function.

I also recall something about them finding that the fine tuning was overkill and they simplified lightening over time, but I could be mistaken.

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