r/canadaguns • u/JerkyMan360 • Aug 04 '26

Misc MRX mag question

Hypothetically if a person were to modify a pump action rifle receiver that uses an AR magwell to fit MRX mags would that be legal? If so would modifying the magazine to have only one set of fins and modifying the rifles’ magwell to fit the one set of fins be legal?

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u/jmz-jmz Aug 04 '26

My understanding is that you can work on / add to / change a mag well, modifying magazines is a big no no. Do more research and don’t take my word for it.

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u/Iokua_CDN Aug 04 '26

My understanding of it is that you cannot modify the magazine.  So you'd have to exclusively  modify the magwell

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u/ExplosiveFetusActual Aug 05 '26

You can modify a magazine all you want, as long as you're not making one to fit in a centerfire semi auto. Shaving off the side ridges on the MRX mags would probably be considered manufacturing an AR15 magazine. Adding ridges to the side (what the MRX mags have) is manufacturing something new, because it won't fit in an AR magwell.

I hand filed slots in my Ruger American's magwell to fit MRX mags. Completely legal. You would have to do something like that.