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Durkin Tactical Franklin Armory
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Posted: 8/20/2017 11:58:35 PM EDT
I've got a Spinta blem bolt in 9mm and I am looking to convert it .40sw. I want to make it work with a Kaw Valley .40 barrel that's on it's way. Is it just opening the bolt face diameter or is there more that needs to be changed?
Link Posted: 8/21/2017 9:32:21 AM EDT
I'm not sure what what point you have to start enlarging the ejection port.  On the ARs in 45acp, that hole is hogged out to allow the fatter cases to fly out.  I wouldn't be surprised to see the .40 and 10mm needing it, too.

I'm sure you already looked at the extractor and the ejector if that's in your bolt rather than fixed in the receiver.
Link Posted: 8/21/2017 10:28:11 AM EDT
The ejection port doesn't have to be enlarged for a 40. If you contact Rudy at Macon Armory he can help you out on the bolt, he specializes in pistol caliber AR uppers.
Link Posted: 8/21/2017 8:42:59 PM EDT
Link Posted: 8/21/2017 10:55:03 PM EDT
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You'll need to modify the extractor hole and possibly the extractor to ensure it isn't restricted form clipping over the rim, and also make sure it doesn't hang onto the case when extracting.
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Thanks! I didn't think about modifying the extractor hole but it makes sense. What do you suggest I open the bolt face diameter up to?
Link Posted: 8/22/2017 7:52:33 PM EDT
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