Is using modified preban mags (Sten, Uzi) to fit in pistol caliber AR's leagal? I had someone question me on this when I was shooting my Oly PCR45 with its Oly modified UZI 20 round mag. Can someone clear this up for me?

They are legal since they can still be used in the gun they were intended for. Olympic Arms welds on the square tube in a way that it can be converted back easily (I don't know exactly how, I'm sure someone here knows).

Its legal because you can jusr grind the block off and put it back into an uzi

Thanks for the info. I'm waiting on some modified grease gun mags from Dalphon, they appear to be modified just like the Oly Uzi mags.

Quoted: Thanks for the info. I'm waiting on some modified grease gun mags from Dalphon, they appear to be modified just like the Oly Uzi mags.

No one has brought up the issue of the legality of Dalphon mags specifically.  When one examines a Dalphon mag--the modified Grease Gun mags in particular, you can see that Dalphon removes the "foreskin" and crushes the top of the magazine.  My question is this: how could a magazine modified in this way possibly still be useable in the original gun it was designed for?  Inquiring minds want to know.

To help clarify the legality of the Dalphon mags ... the Grease Gun mags are manufactured as described above and to reverse the process while still leaving the tops necked-down and adding "foreskin", these mags will again function in a Grease Gun.  Additional work went into making them and so additional work is needed to return them to their intended purpose.

Quoted: To help clarify the legality of the Dalphon mags ... the Grease Gun mags are manufactured as described above and to reverse the process while still leaving the tops necked-down and adding "foreskin", these mags will again function in a Grease Gun.  Additional work went into making them and so additional work is needed to return them to their intended purpose.

Scot, thanks for the info.  You know, if Dalphon's conversion is still considered OK by ATF because they can be returned to their original format, then I see an uneven application of the law by ATF (big surprise there).  Several years ago, Armalite was forced by ATF to re-silver solder all the little rectangular plates on the back of their AR-10B magazines, because ATF said the mags would no longer work in a M1A.  If ATF applied the law the same way to both companies, then the AR-10B mags would be legal without the little tab, because if you wanted to revert the mag, you'd just put the little plate back on.

Thoughts?

I'm the first to admit I'm no expert on the law, but we had an ATF agent spend the last 3 months auditing our facility at Dalphon.  Our entire operation was looked at carefully.  The agent inspected our mags and made a couple recommendations, but did not prevent us from selling them.  Perhaps we're looking at a case-by-case basis by the ATF and/or each having a very different interpretation.  I can appreciate your concern for wanting to follow the law and we share that same concern.  I can only go by what I know applies to our business and really can't comment on the issue with Armalite.

Wanna buy some mags?

Quoted: Perhaps we're looking at a case-by-case basis by the ATF and/or each having a very different interpretation.

I think you are right here, Scot.  Also, things may have changed over at ATF since the time Armalite had thier "problem."  My guess is the same thing would not happen there now.  Different agents, different Administration.

Wanna buy some mags?

 No, thanks!  Maybe later, when money looks better.