I have a dozen or so Colt 20 round straight body mags dating from the late 60's. Most are in the original wrappers and I've really only used one to any extent. They have the aluminum followers.

They are marked:

COLT AR-15
CAL .223
COLT'S PT. F.A. MFG. CO. INC.
HARTFORD, CONN. U.S.A.

What sort of material were they using for the springs at that time?

How do they compare with quality mags available today?

How many cycles could I expect before the springs need replacing (keeping in mind that at this rate I will need replacing before they do. Would you replace the springs with chrome silicon if you thought they would be getting heavy use at some point? And would todays springs intended for the 20 round anti tilt body mag be okay?

Thanks. Most of this is academic. Reading the mag forum has piqued my curiosity.

The 223 marked mags were made in 64-65. Then stated 5.56mm, they are 40 yrs. old, I would not hesitate to use them as is. I have 1/1doz. of them marked 223. They were made by Universal Industries for Colt. You can see their logo on the front of body. All other 20's during 60's were made by Adventure Line Mfg. You can replace springs if you like Wolfe has CS and Brownells has SS and wou can allways cut 30rnd springs to fit 20's. Hope this helped?

Thanks for the info. I am probably going to order a set of spare springs for them, as well as a few followers. No down time if something goes blooey.

Don't worry about the followers, they never wear out. (I'm still waiting for someone to show me a pic of a "worn out" alloy follower)

Kurt,
A CP or Brownells 20 round spring will not work in your straight 20, you will need to cut 1 to 11/2 coils to make it work. I do not know if the Wolf spring will work without cutting.
The original springs would be stainless steel made by a spring company in Farmington, Connecticut.

CP