In my post about the condition of the cotter pin in my ar I was told that it may be from using a "notched"
hammer.
ar15.com/forums/topic.html?b=3&f=118&t=248636

here are some pix.

this is the original hammer


I replaced it with a hammer with a  notch
Is this what every one is talking about?


Think using the noched hammer may solve  the problem?

It may, but  a new carrier will solve your problem the one where the fp is complently covered. I hasve a Colt 6721 that was eating pins, I just put a new carrier in and 1,000 rounds later no bent pin.

In this and the other post listed, All if have seen is solutions to a problem, but not the reason why.

Ok, the Colts have been using the notched hammer for a long time.  It works, and prevents the action from allowing hammer follow threw when the disco fails.  Now in regards to your rifle, we need to start at the beginning of the problem.

From the start, the geometry of your trigger is wrong.  .  This means as the trigger/disco sear holds the hammer sears in the cocked position, the hammer is retained higher in the receiver, and allows the tip of the hammer to catch the firing pin collar as the carrier moves forward back across the hammer. Since adding metal to the trigger is out, then it’s either to lower the top of the hammer, or to solve the catching problem by replacing the carrier with a shrouded unit that protects the firing pin.  As for just changing out the trigger, good luck finding one that is correct, and doesn’t just put you back in the same boat.  

Also to point out, you may want to check the Firing pin collar against the carrier ramp cut.  To check, push the firing pin against the back of the carrier, and run your finger down the ramp.  If the collar edge sticks up past the ramp, pull the FP, chuck it up in a drill and spin file the O.D. of the collar to reduce it to allow a flush fit against/with the ramp.

With new carriers tending to run a bit more money that you may be wanting to spend (and leaving you with a carrier that you would not be needing), My suggestion would to correct the hammer tip of the original hammer to fix the problem (and the FP collar is it too is at fault).

If you look at the new L cut hammer, you will notice that the new hammer has a wear line on very top of the hammer.  This line is be created by the firing pin collar, and where the metal must be relieved to allow the FP collar to glide past smoothly.  Using the new hammer, make two marks on the old hammer.  The bottom mark will be the bottom of the New L cut, and the top mark will be the collar tag line that is being shown on the new hammer (past the top of the L cut).  Once you have these two marks on the old hammer, use a grinder and re-radius the old hammer (top of firing pin contact area) to round out on these points.

Now to point this out before anyone loses their mind, the dimensions of the M-16 hammer top/tip height is more than needed on a semi auto action (this is why the L cut works).  The lowering point on a M-16 hammer in the receiver that requires the top leading edge on the hammer to be higher is due to the auto sear.  Not only does the M-16 hammer have to be lowered past the disco engagement point, it needs to be lowered past the auto sear engagement point as well. Since the semi does not use an auto sear, then lowering/rounding the tip of the hammer’s contact area does not affect the function of the FCG (read as long as you don’t go buck wild and lower it too much and the carrier does not lower it low enough to allow disco sear engagement).

My suggestion is instead of just throwing more money at the rifle, you just spend a little time bring the rifle back into overall working spec.  As I have bitched about numerous times, there is not real spec for the AR-15 semi auto rifles/parts, and each manufacture just strives to build their rifles into a working specification.  With that in mind, unless you want to just spend more money on parts, just bring the parts into a working condition with each other, and the rifle into a functioning unit as a whole.

Way to look at it is since you have already bought the new hammer; it’s time you earn your WECSOG wings.  Worst cause, you lower the old hammer too much and it doesn’t lock onto the disco.  If this is the cause, you have started to learn to use a grinder in a rolling motion, and now can simple just round back the tip of the new hammers (past the collar wear marks being created on it), and will solve the problem as well.

To sum it up, if your looking to throw in new parts, it’s been covered, and the manual will take you far on which part to replace.  On the other hand, If you looking to smith and correct parts, then welcome to the trouble shooting section where we aren’t afraid to modify a part to bring the rifle back into a working/functioning condition.

Checked my buddies older Colt match target. His hammer has that "L" noth and well over 10,000. thru the rifle. He is still on the org fprp. Funny thing Colt did not use the "L" cut hammer on my rifle, but still used that 1/2 circle carrier.

I went the "enhanced" carrier route, I just like the feel better when charging the rifle. due to the shallow angle the rifle is smoother.

110 for a complete bc group. Now I have a spare bolt. Being me its only time untill I put my spare parts into another rifle.