I was having light strikes on hard primers so one recommendation I came across was to put in a stronger hammer spring.  I bought a Wolf extra power spring but after installation I realized that my trigger pull was significantly harder.  I essentially messed up a nice single action trigger to one that much too heavy for me.

Any suggestion as to the remedy, other than going back to the original springs and quit shooting military steel ammo?

Let's see install pics, I'm thinking you installed the first spring upside down but not the second...

No install error.  I check the installation when the post about light hammer strikes was posted by someone else last week.  In other words, original hammer spring was OK as in the Wolf XP spring.  

But the question still stands.  Does the hammer spring really affect the trigger pull?

Yes, a backwards hammer spring makes trigger pull damned nice

Possibly your original was wussy.
Try a different standard spring (you should have one in your spares and they are pretty cheep)
Good luck

Yes the heavier hammer spring increases the load the trigger has to over come to drop the hammer.  In the 1911 world, Ed Brown makes a 19# spring to replace the 24# spring.  Lightens the trigger pull a little...

The hammer spring accounts for most of the trigger pull feel in an AR, the trigger spring is really just helping reset the trigger after firing.
Assuming there was nothing wrong with your original spring and it was installed correctly, and you already checked for other causes for light strikes such as build up adding friction to the firing pin's movement then you either need to get different ammo or recheck things. A standard spring with an otherwise working rifle should not have primer issues with hard primers. Now, if that spring is softer than it's supposed to be, then you have a different issue, but you should never NEED an extra power hammer spring in an otherwise normal AR. Heck, most of us use LIGHTER springs and still set off mil-spec ammo reliably.

Maybe a drop of lube spread around on the firing pin before putting it back in the bolt after cleaning? Triple check it's clean in there and that your hammer isn't binding on the receiver's sides.

+1

The sear is ground at a positive angle.  Watch the hammer as you pull the trigger, it moves back against hammer spring pressure.

If you are positive your first spring was installed correctly and gave you problems, I would try a different standard spring. As was said, your stock spring should have worked fine. In many years of building many ARs I can't recall an instance of having a standard spring not work. Not saying it's impossible. It just has never happened to me. In fact I have a 5.45x39 upper that I solely shoot surplus Russian corrosive ammo that is notorious for having hard to ignite primer. Upper came with extra power spring but I have not changed the stock spring in my lower and not had a problem in over 1000 rounds fired.

No sear in an AR15. You may be referring to the engagement surface of the trigger ?

This is good to know. I had a pretty slick Spikes battle trigger in the lower I used for my 5.45 build. Once I installed the heavier supplied hammer spring my trigger pull changed drastically (for the worse). I intended on re-installing the origional hammer spring but was concerned the Russian 7N6 ammo primers needed the heavy spring. Thanks for this info.
Yes, a heavy hammer spring affects your trigger, this proved it to me.

They are indeed sear surfaces.  But because there is no sear, stacking or rearward movement of the hammer is a result of this simplification of the firing mechanism.



 

I was having a fairly high FTF rate on Wolf ammo.  I installed a Wolf spring and it solved the problem!  Trigger pull increased slightly, but it isn't bad.