ar15 9mm hammer question

[kiki]

can anyone please explain why a regular ar15 223 hammer wont work on a 9mm upper???? why does the hammer need to have a cutout and lightend????? and will a 9mm hammer work on 223 upper???

[xrayoneone]

The notch on a regular AR hammer can get caught on the bolt. I have heard you can run a 9mm hammer without problems in a 223. The rounded DPMS hammer can be used without issue with some 9mm bolts.

My 9mm is a dedicated 9mm, I can't place a 5.56 upper on it unless I want a single shot so I haven't tried it out.

[rjrivero]

If you're planning on running multiple caliber uppers on your lower, then use a DPMS style hammer. You won't have any worries on catching your hammer on the bolt.

[kiki]

are you talking about the notch on the top of the hammer...my stag hammer doesnt have that notch.....and i was thinking of polishing the face and rounded top for less friction....

[Robb Jensen]

are you talking about the notch on the top of the hammer...my stag hammer doesnt have that notch.....and i was thinking of polishing the face and rounded top for less friction....

Yes. If there's no notch in your hammer then you won't need a 9mm hammer.