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Posted: 2/12/2026 11:23:23 AM EDT
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How doable is a .327Fed mag AR? I saw that the .357mag was built using DE mags. Could that mag be adapted or would the attempt need to start from scratch? Thank you. |
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The case body and rim diameters are different. Are they different enough to preclude successful feeding of the 327 in a 357 mag? I don’t know for sure, but my SWAG is that it won’t without tweaking the mag feed lips. And even then you still have a slight difference in cartridge OAL, and that too could cause feeding issues. Tromix might drop in to offer better insight. He certainly has experience in different AR chamberings. |
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In answer to the original question, I was able to fit eleven .327 Fed cartridges into a Desert Eagle .357 magazine. To actually get them to function would require some adjustment to the feed lips. It may be necessary to shim inside the mag to reduce the lateral dimension to better match the smaller diameter cartridge. 
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Originally Posted By GarrettJ: In answer to the original question, I was able to fit eleven .327 Fed cartridges into a Desert Eagle .357 magazine. To actually get them to function would require some adjustment to the feed lips. It may be necessary to shim inside the mag to reduce the lateral dimension to better match the smaller diameter cartridge. https://www.ar15.com/media/mediaFiles/55694/IMG_0007-3712451.jpg I guess about .02 per side |
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Or , you could swell up the case the equivalent to approximate the 357 case. Trim a 300blk down to 33mm and neck it for .312 327 bullets. Some good bullets in the 100-130gr for .312 . Loaded at 60ksi , they'll hit different than the 327 federal. * a rimless "Martin Meteor" . |
Assuming you could find a mag that would work, I think Ron Williams is still doing custom upper requests. He's the guy that made the 357 magnum DI uppers, and I intend on commissioning one once my car is paid off.  But he does a lot of wildcats as well.It's been a few years since I've talked to him, but the uppers were around $1k back then, fyi. https://rmwxtreme.com/ |
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