Here is the skinny:

Not until I changed the front sight to a 4 rail gas block that after 60 rounds my mags ( 3 in one day) started to open up.  Just to define this it looks to me  like the extractor is really beaten up the top of the mag. What is going on??. Everything on this AR is basically new.  I can't figure it out is it the gas block or what?  HELP!!  Does this make since or do I need to give more detail?

What kind/brand of magazines?

It doesn't say what brand on  the mag. I have a 5, 20, and 40 round steel mag. All today totally busted. I had to push in the top of the mag just to keep the ammo from freely jumping out. I have used these mags on other AR's of mine and I have never had this problem before.  I did install a reduced power action kit for my trigger as well along with the front sight . Would the spring action make a difference? It does seem a little slower. Not as much spring. Man this is really driving me crazy.
I looked at the originally front sight and I noticed a hole beneath the sight . On the 4 rail there is no hole for the air to pass through the barrel.  It seems to copme out the pin up above. That's another concern.

First off, look at the back of the mag where the feed lips return down the back of the mag. Are the feed lips continues all the way down to the back channel slot (follower portion that raises the bolt hold open when the mag is empty), or does the lips end before turning down?  On a USGI mag, the lip is formed all the way down to strengthen the mag lip.  On clone mags, the lips do not continue and are shaped like that of a M-14 mag. If you are using Clone mags, they are problem children and could be the soul source of the problem, hence the reason that the question was asked on the type of mag.  Also, I see that you have stated that the mags where steel, which leads me to further believe that the mags are cheap clone types (USGI mags are aluminum).

Regarding the reduced springs, as long as you didn't clip or use a weaker recoil spring (buffer spring), the hammer/trigger springs are fine.  Most of use here tweak our stock hammer/trigger springs to do the same as your new springs, so don't let the springs throw you off the real problem, which sounds like you have cheap Clone mags.

Note: The problems with the clone mags are that without the reinforced feed lip support, the lips tend to spread open over a very short time, and cause feeding/binding problem. The quick fix is to just re-bend the lips back into shape, but due to the lack of back support, the lips will just open back up in a very short time.  Evermore, re-bending of the lips weakens the metal and they crack off in just a few re-bending.

P.S. If anyone has a source (photo) of the feed lips of a USGI mag, please post it.

Dano,

You're in luck, this came through the AR15-L, from ARF Mag forum, today.

[url]http://www.armscenter.com/xm777/HK-SA80-A2-3.jpg[/url]

[url]http://www.armscenter.com/xm777/HK-SA80-A2-4.jpg[/url]

[url]http://www.armscenter.com/xm777/HK-SA80-A2-5.jpg[/url]

HK AR mag compared to a USGI, USGI on the right.

Well I looked and yes they are chead mags. The lip does not continue down the side. I went ahead and bought a USGI mag maybe it will resolve my issue. Thanks for the info.

mdale1911