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  #11  
Old 01-05-2010, 01:58 AM
Travlin Travlin is offline
 
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Rondog -- Interesting post and good photos.

The cutouts in the receiver are for the magazine lips, and to extract the bolt. If you need more assurance that your carbine is normal try this. Remove the stock and trigger group. Disconnect the operating handle from the bolt, or remove the slide. Move the bolt fully to the rear of the receiver.

Now insert and hold an empty magazine in the receiver. Looking down from the top you can see that the feed lips EXACTLY match the cutout you were concerned about.

Next move the bolt forward into battery and turn the receiver upside down. Rotate the bolt to unlock the lugs and pull backwards slowly. When the lug reaches the cutout it can rotate further so the bolt can be removed. Put bolt lug back in the track and move further to the rear past the cutout and notice that it cannot now be rotated.

This proves that the cutout is a clever part of the design and not a problem. Thanks for bringing this issue to my attention. After reading one of the linked threads I came up with this exercise and learned something new.
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  #12  
Old 01-05-2010, 09:59 AM
KnickKnack KnickKnack is offline
 
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Location: Glens Falls, NY
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The last carbine I received from CMP also had rouch machining. I sent a picture of the receiver to the armorer at CMP and he assured me that it is normal and fine to shoot that way. They did offer to inspect it closer if I wanted to send it back, but I trust that it is indeed fine. I guess when you're rushing to manufacturer over 6 million military weapons in such a short time to supply a war effort, they aren't all going to come out perfectly machined.
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  #13  
Old 01-05-2010, 05:24 PM
Emmett Dunham Emmett Dunham is offline
 
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I would take a fine stone and smooth the areas that are raised these could become pointers under stress for a crack to start from.


Emmett
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  #14  
Old 01-05-2010, 10:03 PM
TexTenn59 TexTenn59 is offline
 
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Emmett, I have been shooting for a while, but have not ventured off into anything but very minor gunsmithing... What "stone" you are referring to and where do you get them?

Thanks for a reply.

Wayne
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  #15  
Old 01-05-2010, 10:14 PM
Rondog Rondog is offline
 
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Location: Parker, Commurado
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Quote:
Originally Posted by TexTenn59 View Post
Emmett, I have been shooting for a while, but have not ventured off into anything but very minor gunsmithing... What "stone" you are referring to and where do you get them?

Thanks for a reply.

Wayne
Similar to knife sharpening stones, only smaller and in various shapes, sizes, materials and grits. Brownells and Midway have kits of 'em. Used for gentle polishing & deburring of steel parts, like sharp edges and sears, things like that.
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  #16  
Old 01-05-2010, 10:27 PM
TexTenn59 TexTenn59 is offline
 
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Quote:
Originally Posted by Rondog View Post
Similar to knife sharpening stones, only smaller and in various shapes, sizes, materials and grits. Brownells and Midway have kits of 'em. Used for gentle polishing & deburring of steel parts, like sharp edges and sears, things like that.
Various shapes and sizes...Great, now I need to buy one of all to try them out. This could become addicting.

Thanks for enlightenment.
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  #17  
Old 01-05-2010, 10:32 PM
Rondog Rondog is offline
 
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Location: Parker, Commurado
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Quote:
Originally Posted by TexTenn59 View Post
Various shapes and sizes...Great, now I need to buy one of all to try them out. This could become addicting.

Thanks for enlightenment.
http://www.brownells.com/.aspx/pid=9...t/INDIA_STONES
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  #18  
Old 01-05-2010, 11:39 PM
BQ97 BQ97 is offline
 
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The scalloped cuts in the receiver are done to mate with the feed lips of the magazine but they have nothing to do with the removal of the bolt. The left bolt lug goes up and to the right upon removal never coming close to the scalloped feed lip cuts. The receiver does have a bolt clearance cut, which is necessary for bolt removal, but it isn't pictured.

The bolt clearance cut is located on the left side, just to the rear of the upper bearing surface. The bolt clearance cut ends directly centerline of the rear sight dovetail. When the rear of the bolt is in this roughly 1.02" area the bolt will tilt to the right and the left lug will be completely free of the rail cut in the left side of the receiver. Most carbine receivers will also have a firing pin tang relief cut o the right side of the receiver. It is smaller and directly opposite the bolt clearance cut.
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  #19  
Old 01-07-2010, 02:09 AM
Travlin Travlin is offline
 
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BQ97 -- I stand by what I said in post 11. You are right that there are also cut outs for the rear end of the bolt that appear to be necessary for removal. But they won't allow you to rotate the bolt out of the track without the cut out near the front of the track for the left lug that the OP referred to. Try the exercise I described above and you will see this is true. The bolt simply won't rotate out of the track without this.
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  #20  
Old 01-07-2010, 05:09 PM
BQ97 BQ97 is offline
 
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If the bolt wouldn't rotate out of the receiver without the scalloped cuts for the magazine feed lips why is it you can remove the bolt with a magazine inserted? Also, if the feed lip cuts were necessary for removal of the bolt why is it the M1 Garand doesn't have a similar cut in the same area? The Garand does however have a similar cut toward the rear of the bolt so it too can tilt to the right as you would expect due to the similarity of bolt and receiver design. On both the M1 Carbine and M1 Garand the bolt is extracted up and to the right with about a 50 degree angle from horizontal. Upon extraction the left lug on the carbine bolt goes up and to the right cleanly out of the receiver rail, just like the M1 Garand, and away from the scalloped cuts. Take some modeling clay and fill in the area under the bolt thus eliminating the scalloped cuts. You can still remove the bolt.
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