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Posted: 2/22/2007 2:45:52 PM EST
I have a couple of Colt Bolts and they have little angled cuts in the bolt body behind each of the locking lugs. What were these cuts intended to do? Thanks.

Mine looks just like this one;

Link Posted: 2/22/2007 8:46:51 PM EST

Originally Posted By Powerkicker:
I have a couple of Colt Bolts and they have little angled cuts in the bolt body behind each of the locking lugs. What were these cuts intended to do? Thanks.

Mine looks just like this one;

www.biggerhammer.net/ar15/barrelsbolts/boltcarrier_c_stamping.jpg

I remember a thread about these a few months ago. The older bolts that were cut on non-CNC milling machines have those cuts because a human can only move the mill in one axis at a time and keep things accurate enough.

Newer bolts cut on CNC mills don't have the cuts because the machine is able to rotate teh bolt at the same time that it moves it across the rear of the lug.
Link Posted: 2/22/2007 9:40:29 PM EST
Link Posted: 2/23/2007 11:28:02 AM EST
Thanks.
Link Posted: 2/23/2007 12:27:55 PM EST

Originally Posted By AR15barrels:
The cuts are to aid reliability in the bolt's ability to cam onto the barrel extension's lugs.
If you look at the inside of the barrel extension, it also has camming surfaces on the leading edge of the lugs.


Randall,
I think he was referring to the little angled machine marks on the body of the bolt, not the camming angles on the lugs themselves.

You basically find them on early Colt bolts. The newer production doesn't have them because of production changes mentioned above. I recently acquired a milsurp FN bolt assy, and was interested that in the place my early Colt bolts have those little cuts, the FN piece has a tiny dimple; right at the base of where the camming angle is on the lug.
Link Posted: 2/23/2007 2:27:38 PM EST
[Last Edit: 2/23/2007 2:32:52 PM EST by AR15barrels]
Link Posted: 2/24/2007 3:37:10 AM EST

Originally Posted By AR15barrels:

Originally Posted By shamayim:
I think he was referring to the little angled machine marks on the body of the bolt, not the camming angles on the lugs themselves.


The angle I SEE in the picture posted above is the tool overrun from the tool that cut the camming angles.
Basically, the smaller diameter lug "root" got hit by the endmill making the chamfer.

www.ar15barrels.com/tech/lug-chamfer.jpg

On LMT bolts, the lug roots are not as prominent and you don't see these marks.
On CMT bolts, there is a little "half moon" cut where the endmill ran-off into the lug root, but they programmed the tool to stop there and did not continue the tool path all the way across the lug root like on the colt bolt pictured above.


Those are the angled cuts I was asking about. Thanks again gents.
Link Posted: 2/24/2007 4:14:54 AM EST
Whoops. My mistake Well, it's been a screwed up week all around.
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