I was rummaging through my spare parts today, and I noticed I have 2 types of firing pins. Some had a larger collar. Thinking I was crazy, I did a search online, and there are discussions on this, but it's all vague.

Hive Mind:

What is the difference, if any, between the two types of firing pins? Thanks.

I've wondered the same thing for a while.  

IIRC, www.biggerhammer.net has some information on firing pins - I believe you are looking at an older firing pin vs a newer one here but cannot access the Biggerhammer site from work here so I cannot be definative w/ my comments......

Check it out,
mike

i took a look. i found specs for an ar15 firing pin. he also compares different hammer types. i did not find a comparison on the types of firing pins.

The large ring on a simi-AR FP is designed to get caught on the flat step of the hammer in order to avoid a out of battery ignition if the disconnector fails to capture the hammer.


Or so says Armalite/Colt in the book "Black Rifle II."

The large collar is an M16 style pin. The small collar is an SP1 Ar15 style pin. The firing pin collar was reduced so the the SP1 style parts would function correctly. The firing pin collar is exposed on the SP1 style carrier because of the milled ramp. The firing pin collar would hang on the hammer notch most of the time if the collar was not reduced instead of just when the disconnector failed. There are some pins that were sold as Ar15 style pins that are larger than they should be for a AR15 SP1 style pin but smaller than a M16 style pin.

If your bolt carrier covers the firing pin you can use either one.

once again the hive mind knows the answer...nicely done. thanks.