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12/13/2008 12:16:47 PM EDT
A Colt full-auto firing pin and a Colt semi-auto firing pin?
12/13/2008 12:35:28 PM EDT
[#1]
Yes, the shoulder size is slightly different, and the nub on the end might be slightly different in size as well.  

Sorry I can't be more helpful or give you pic reference... but I did answer your question.  I'm sure someone will be along with photos in a moment.

~Augee
12/13/2008 1:19:47 PM EDT
[#2]
12/13/2008 1:38:28 PM EDT
[#3]
Hmmm, why the difference? And which one is which?
12/13/2008 4:16:34 PM EDT
[#4]
Um. according to what I am seeing in that pic, which is pretty damn detailed, I don't see a difference. Is that the point you were trying to make?
12/13/2008 4:36:42 PM EDT
[#5]
I see a slight difference, if you look all the way at the left they are aligned.
Then after the point of the firing pin it appears the shoulders are different.
And on is slightly longer then the other, though not by much. I still don't
know which is which though
12/13/2008 5:16:58 PM EDT
[#6]
Quoted:
Um. according to what I am seeing in that pic, which is pretty damn detailed, I don't see a difference. Is that the point you were trying to make?


No, I actually have a gentleman's bet on whether or not there was a difference.  I said there was no difference and he said there was...
12/13/2008 8:09:20 PM EDT
[#7]
The top FP in the photo above is the larger shouldered M16 FP. The bottom FP is the AR15 FP.

I believe the smaller shouldered AR15 FP came about when AR15 bolt carriers were designed “un-shrouded”. If the larger shouldered M16 FP was used with the un-shrouded bolt carrier, interference between the FP shoulder and the hammer could take place.

This is my personal understanding as to the reason for the difference between the two types of firing pins. I’m open for any more detailed explanations.
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