Sigma 75-300mm question

Hello Pentaxians!

I recently ordered a used zoom lens and I can't mount it to my camera (Pentax K1). The lens is an old Sigma APO 75-300 f4-5. It has a plastic flange (or something) extending past the mount base plate (as pictured). The plastic over-lap will not allow the lens to make full contact with the camera. I'm will likely just file the plastic down, but I thought I would consult professional advise first . Any help would be much appreciated. Thanks, Rick

that does not look like a Pentax K mount at all. It should look like this link if you try too hard mounting it, it could damage the camera

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Barrie
Too Old To Die Young

http://www.pentaxphotogallery.com/artists/barrieforbes
https://www.flickr.com/photos/189482630@N03/

No, that's not compatible.

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Best regards, John

If you were sold it as Pentax compatible you have a case to return it to the seller.

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John K

that is not pentax just checked mine and it is totaly wrong

I've only had fleeting use of them so can't be entirely certain, but that looks a bit like a Nikon F-Mount?

As stated by others above, it's sadly not a Pentax fit, I'm afraid.

An example of an F-Mount Nikon lens
:

Interesting. Thanks for all the replies. Good to know it's not Pentax. I'll try and return the lens.