Hey everyone! After a recent hunting trip I decided to knock some weight (and size) off my custom .260 Rem chambered rifle and one of the areas I identified was the magazine. I was having a little trouble getting my rifle to fit in the scabbard in my pack due to it hanging up on the 5 round AICS magazine protruding. I did a quick search for a 3 round AICS magazine but as most of you know this doesn't exist. However, Ruger makes a 3 round polymer magazine for their Gunsite Scout rifle. The GSR uses the same AICS pattern magazines so I figured I could get one to work in my rifle. I ordered one for about $30 and gave it a try.
Take a look:
The Ruger GSR 3 round polymer magazine comes in at 1.9oz

The AICS 5 round steel magazine comes in at 5.5oz

Here's a size comparison between the two. In my rifle only the GSR magazine's base pad protrudes from my stock.

However, I did have to do some modifications to the 3 round GSR magazine to get it to fit and feed reliably in my rifle.
1) The first thing that I had to do was lower the feed lips. I just turned the magazine upside down on a file on my table and went to work until the top points were filed down to flats. It would then click into my rifle reliably.
2) I was then having a problem with it reliably loading rounds into the chamber. It was usually only loading the first round okay and failing on the other two. The fix for this was to shorten the magazine lips by removing the front 1/3" to 1/4" on each side and then lubing the inside surfaces of the magazine (the follower would catch from time to time on the inside).
Here's the finished product (the area in red is where I filed material off):



Hopefully this helps someone else out!
Take a look:
The Ruger GSR 3 round polymer magazine comes in at 1.9oz

The AICS 5 round steel magazine comes in at 5.5oz

Here's a size comparison between the two. In my rifle only the GSR magazine's base pad protrudes from my stock.

However, I did have to do some modifications to the 3 round GSR magazine to get it to fit and feed reliably in my rifle.
1) The first thing that I had to do was lower the feed lips. I just turned the magazine upside down on a file on my table and went to work until the top points were filed down to flats. It would then click into my rifle reliably.
2) I was then having a problem with it reliably loading rounds into the chamber. It was usually only loading the first round okay and failing on the other two. The fix for this was to shorten the magazine lips by removing the front 1/3" to 1/4" on each side and then lubing the inside surfaces of the magazine (the follower would catch from time to time on the inside).
Here's the finished product (the area in red is where I filed material off):



Hopefully this helps someone else out!