Recently this was noticed in a photo I posted (this is an enlargement):

The magazine on the right was one of two that came in the box with my like-new AM III in 30 Carbine and the one on the left I bought as a spare. Somebody here said one is a 9mm magazine, differentiated by the different angle on the end of the follower. Since the two that came with the gun are like the one in the right I assumed he meant the one on the left was a 9mm magazine. 

Comparing notes with John Lodahl, he sent me pics from his collection:

The mags on the right have a follower with a flatter profile at the end and are purportedly from 30 carbine guns. The one on the left has a black follower and is from a 9mm gun. 

So, what’s going on here?  My initial thought was that the one with the longer flat portion of the follower was a 9mm magazine based on what was pointed out in the other post. But my 30 magazine followers have the same shape as John’s 9mm follower. 

Given that the magazines are all unmarked, what (if any) is the distinction between 9 and 30 magazines?  Or are they all just the same, and the different follower shapes are an early vs late production thing? Or did my 30 Carbine gun just happen to come with a pair of 9mm magazines by mistake? (The seller had numerous AM IIIs and could have mixed them up).

Please, educate us if you can!

That is what came with my 30 and 9mm guns as well.

However, it would not surprise me at all, that AMT shipped guns with mis-matched magazines if they happened to be out of stock of the correct mag at the time.  Knowing how AMT operated, it would be a fair bet that some 9mm guns were shipped with 30 carbine mags and vice versa. 

Tony

I’m still confused. We are talking about two different shapes and you refer to ‘that’ without specifying which you are speaking of?

Black follower that has a smaller flat usually shipped with the 9mm guns, and orange follower with the larger flat usually shipped with the 30 carbine guns.  But if AMT was out of stock, they most likely shipped either mag with either gun.

The small flat orange follower may have been for either one or they decided it would work with both.  I don't know.

Tony

The top magazine in the pics above has a shorter base and a longer flat front on the follower. Are you saying this is what the 30 Carbine magazines looked like, and the 9mm magazines had the longer base and shorter flat section?

Or did the 30 Carbine and 9mm guns all get the same magazines, and the magazine design changed partway through production, so the issue is early vs late instead of 30 vs 9?

My 30 gun came with two magazines of the long base/short front variety…and it seems to feed and eject fine?

I have 3 automag iii’s in 30 carbine with 5 magazines, and they all have the longer flat part in the front. All 5 magazines are like the one on the LEFT of the first picture in this post. 

Now that I think about it, I had a AMT automag iii that blocked every time when shooting, and that one had a magazine with the shorter flat part in the front. The 3 guns that I still have are all IAI. Maybe that has something to do with it? 

I understand why you assumed what I meant, but if you read again what I wrote and if you look at the picture in that thread again, I actually meant the opposite 

So my 30 carbine magazines look like John Lodahl’s 30 carbine magazines…

Ok this is really strange. I tried shrinking the image to about 1/10th of its original size, I tried giving it more light, also making it a bit blue-ish, saving it as a bmp, jpg, png etc, and nothing worked. I try cutting off the guns, and it works from the first time…

So hereby the picture of my 5 .30carbine mags…

They all have the same type of follower. 

The previous owner of the first magazine has glued a little piece of white plastic where the follower catches the slidestop. I guess it has something to do with the angle of the follower. You can clearly see that the follower of the other 4 mags sits slightly higher in the front. Works perfect like this. No feeding issues with any of the mags. 

Really strange! As long as you can see a complete gun on the picture, it won’t upload. 

When you cut just a little piece off, it works. 

Well, this is odd for sure.....

Here are 5 mags.  One of the orange follower ones is Mike's, the other 3 orange followers are mine.  The one with the black follower is for my AMT-III 9mm WM.

I've been trying to figure this out with Mike.  Mike mentioned (and Mike, please correct me if i am wrong), that he has an AMT-III 30 Carbine.  Two of his mags fit and function great, and one "drags" as soon as it is inserted into in his magwell.  He mailed it to me for comparison.  So, I measured his with my three 30 carbine mags, and my 9mm WM mag.

Here are my numbers (below).  When I say "lip", that is measuring the back of the mag, the "U" shaped area (that Luc measured and posted above).  Note, my "lip" measurements are just the opposite of Luc's measurements.

I checked all 5 mags in my IAI 30 carbine.  They all insert with no "drag".  They all "fall out" into my hand when the mag release button is pressed.

I checked all 5 mags in my AMT 9mm WM.  Again, they all insert with no "drag".  They all "fall out" into my hand when the mag release button is pressed.

All 5 fit without drag in both my pistols.

Mike is having "drag" issues with 1 of his three mags (the one he sent me), and no drag issues with the other 2.  

With all this being said, is it possible, just maybe, that Mike's AMT III 30 Carbine is actually a 9mm WM frame with the 30 carbine upper?

Could my IAI 30 carbine, and AMT 9mm WM, both have 30 carbine frames and different uppers?  This would explain why the "larger" magazine "drags" in Mike's, and not in either of mine?

Mike and I both agree that it wouldn't make financial sense to actually cast 2 different frames to accommodate the 2 different calibers for a magwell difference of approximately 0.025".  (Sort of the same concept for the AMT-IV in 45 WIN MAG and 10MM Mag.  It's assumed that both of those frames are the same too, right?  In fact, isn't the AMT-V in 50 AE the same frame as the AMT-IV?)

Maybe in the beginning AMT had 2 different frames cast, then later (because of the whole AMT / IAI fiasco's) just went with the one "larger" frame and 2 different uppers to accommodate both caliber sizes?

Here is a 9mm WM round inserted in a presumed 30 carbine magazine.

The different dimensions in the mags make sense if you look at the dimension of the rounds.

The dimensions at the base of the 9mm is 0.391".  The 30 carbine has a base width of 0.356".

This would explain why a 9mm magazine has a larger "U" shaped area in the back, and the 30 carbine is smaller.

I hope all this makes sense......

There are more differences between iai and amt guns, at least the ones I have or had. 

The ejection port of the amt iii that I had was cut further to the left side of the gun than any of the iai’s, and also the barrel was a few millimeters longer than the barrel of my iai’s. So it wouldn’t surprise me if the frames and magazines are also not exactly the same!

Where is Larry Grossman when we need him???

I though AMT changed the name to IAI when they got sued by Ruger, then back to AMT after that was settled.

Tony

True. But when the AMIII was first produced it was an IAI product. Only after the Ruger lawsuit dust settled did they revert to AMT badging. 

If you look at the first magazine articles when the gun was first introduced (1989 SHOT show), it was badged as an IAI. 

I believe the frame size difference is only front-to-back, not side-to-side….

The thickness of the sheetmetal is the same for both magazines.

The gun seems to function just fine with it. 

My magazines also exhibit the same characteristics at the rear as the ones pictured above. 

I’m speculating the issue isn’t one of 9mm vs 30 Carbine, or IAI versus AMT.  Instead, my guess is that it’s simply an early vs late thing, where at some point a new frame casting was used whose dimensions were fractionally smaller, and the magazines changed at the same time. While it’s possible this transition took place at the same time that IAI became AMT once more, I wouldn’t necessarily assume that’s true. 

All 4 magazines that I have left for my IAI AMiii’s in 30 carbine look like this in the back:

And they are indeed a bit rounded off 

Position of the rounds in the mag:

And a few measurements (all in millimeters):

Measured on this line from the back: 14,85 to 15,06 over 4 mags

Measured on this line from the front: 14,99 to 15,08 over 4 mags

Measured on this line from the back (in the front there is the cutout for the magazine catch) : 14,83 to 15,07 over 4 mags

Measured on this line front to back straight on the back of the mags: 45,32 to 45,40 over 4 mags

The width of the inside of the 3 frames:

Front: 15,70; back 15,35

Front: 15,25; back 15,34

Front: 15,50; back 15,25

So there seems to be little to no difference between the width of the ‘magwell’ of an AMT vs an IAI frame. The difference must indeed be in the length (front to back) like Pantera Mike already said, but I was not able to get a decent measurement of the inside front to back of the frame. My magazines have about 0,5 to 1 mm play front to back when inserted in the frame. 

John’s 9mm gun has the only black-follower magazine I’ve ever noticed. 

Can other people here with 9mm guns confirm or deny that all your magazines have black followers?  Perhaps that’s a simple way to distinguish them?

If we come to learn anecdotally that people with 9mm guns have black followers, we can then delve deeper and try to determine what makes their magazines different from the 30 carbine magazines, apart from the follower color….

I guess it is the same as the one Interarms has on their website (out of stock, but the picture is still there): https://interarmstx.com/product/amt-automag-iii-magazine-30-carbine-stainless-steel-8rd/" rel="nofollow -  https://interarmstx.com/product/amt-automag-iii-magazine-30-carbine-stainless-steel-8rd/

I have six mags that came with my used 9mm Win Mag gun.  They all have black followers.

Tony

Ok great, do they also have this shape?

And that’s all I know. I won’t be able to try it until next week.