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  #1  
Old 06-20-2019, 8:13 AM
gruntinhusaybah gruntinhusaybah is offline
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Default New to me AR hammer issue on install

I'm working on a new lower receiver for a featureless build and ran into an issue with the hammer installation that is new to me.

It's an Aero precision forged lower, using a Daniel Defense lower parts kit.

Once I got the hammer installed I function tested and the hammer falls incredibly slowly. It's like it's being restricted by something. I removed the hammer and trigger, double checked everything and reinstalled and the same issue.

And it appears that the hammer pin is rotating with the movement of the hammer.

Has anyone come across this issue? Any ideas?
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  #2  
Old 06-20-2019, 8:28 AM
baih777 baih777 is online now
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Are you sure you don't have the spring backwards.
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  #3  
Old 06-20-2019, 8:32 AM
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IsaacMc IsaacMc is offline
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yea I would say a little grease and verify everything is in correctly. Sounds like the pin is tight in the trigger area.
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Old 06-20-2019, 8:33 AM
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Quote:
Originally Posted by gruntinhusaybah View Post
I'm working on a new lower receiver for a featureless build and ran into an issue with the hammer installation that is new to me.

It's an Aero precision forged lower, using a Daniel Defense lower parts kit.

Once I got the hammer installed I function tested and the hammer falls incredibly slowly. It's like it's being restricted by something. I removed the hammer and trigger, double checked everything and reinstalled and the same issue.

And it appears that the hammer pin is rotating with the movement of the hammer.

Has anyone come across this issue? Any ideas?
Remove hammer spring and trigger.
Reinstall hammer and hammer pin only in receiver.
Check that the hammer is moving freely in the reciever.

I have run into tight fitting hammers where the solution is to shorten the width of the hammer so that the hammer moves freely.
This is often caused by the corners of the fire control pocket not being milled to a proper corner radius so that the corner radius will clear the hammer.
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  #5  
Old 06-20-2019, 8:42 AM
gruntinhusaybah gruntinhusaybah is offline
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Quote:
Originally Posted by baih777 View Post
Are you sure you don't have the spring backwards.
Pretty sure, I will verify later.

Quote:
Originally Posted by IsaacMc View Post
yea I would say a little grease and verify everything is in correctly. Sounds like the pin is tight in the trigger area.
makes sense

Quote:
Originally Posted by ar15barrels View Post
Remove hammer spring and trigger.
Reinstall hammer and hammer pin only in receiver.
Check that the hammer is moving freely in the reciever.

I have run into tight fitting hammers where the solution is to shorten the width of the hammer so that the hammer moves freely.
This is often caused by the corners of the fire control pocket not being milled to a proper corner radius so that the corner radius will clear the hammer.
Now that I didn't do, I will try that later and post back. Thank you! The hammer was also very difficult to get into position.
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Old 06-20-2019, 9:09 AM
marausch marausch is offline
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I agree on the "hammer width" comment. Sometimes you run in to a tolerance stack up issue with hammer width and pocket width. Sometimes a simple polishing of the inside of the pocket and the ends of the hammer is all you need.

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  #7  
Old 06-20-2019, 6:24 PM
gruntinhusaybah gruntinhusaybah is offline
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Definitely contact between the receiver and the hammer lugs. I canít figure out pictures on here, but there are wear marks in the receiver, so some emery and patience tomorrow and the hammer should be gtg

Thanks!

Or I get a CMC drop in trigger....

Last edited by gruntinhusaybah; 06-20-2019 at 6:34 PM..
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Old 06-22-2019, 11:59 AM
gruntinhusaybah gruntinhusaybah is offline
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BC2510E6-4D08-4CDC-A90F-4E0C5AD6445D.jpg
I managed to get it together, I miked the hammer lugs and took them to my surface plate with some 1000 grit paper and checked the fit every .001Ē until the hammer went in and I felt no resistance in its full range of motion.

Thanks for the tip @ar15barrels

Last edited by gruntinhusaybah; 06-22-2019 at 12:02 PM..
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