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Last edited by bmash; 12-19-2022, 11:41 PM. -
Sounds like you need feed ramp work. https://www.youtube.com/watch?v=Kxz8teLbEPc&t=210s
Some people may recommend magazine modification, but I would first do feed ramp work before I messed with any magazine modification..Last edited by montana; 12-19-2022, 11:49 PM. -
Obviously an AR is not gentle during the feed cycle. Looking at the pic of the two rounds side by side, my eyes see the one round on top with the bullet seated deeper. Check them both using a comparator (so your measurement compares the seating depth on the ogive) for what I consider a better measurement than OAL. This should tell you quick if the feed cycle in your gun is pushing the bullet deeper.
Yes, those noses are being beat up during the ride so something is causing it (I'm being Capt Obvious again but not being sarcastic). That particular magazine may not be helping the situation but you mention using two separate magazines here and both casued an issue? A better picture would be the feed ramp area so we can see that.
Give some more information such as brand of rifle if purchased complete and/or parts list if home built (upper, lower, barrel). I would ask the brand of dies too usually but you stated your problem was specific to that particular bullet. Have you ever checked a cycled round from other ammo? Were they beat up? One of the Sierra PH would tell the tale as that exposed lead tip will show any abuse.
Without seeing the feed ramp, I'll take a SWAG. Your barrel extension has an abrupt "ledge" and the nose of that bullet is hitting it on the way into the chamber possibly enough to cause the round to nose up and catch the bullet nose at the top of the chamber and not go in. A run on sentence there....
Before I install a barrel into an upper, I'll spend some quality time on the feed ramp (and locking lugs so they'll be kinder to the brass on the way out) to make sure this is less likely to happen. I don't "know" what I'm describing is what happened but it is my guess.Comment
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From the photo I can see where the tip of the bullet is catching the barrels feed ramp. The ramps are over hanging the uppers receivers feed ramps and you want the opposite when fitting the barrel to the upper. https://www.youtube.com/watch?v=aAab4l75FEI..Originally posted by bmash View Post
Depends on the gunsmith, they come in all varieties from excellent to horrible..If doing it yourself, always remove the barrel from the upper before doing any feed ramp work, you
don't want to cut into the hardened anodized upper feed ramps exposing the soft aluminum underneath.There is zero benefit cutting into the uppers feed ramp and will ruin the upper.
If you are careful and don't change the ramp geometry too much, you can be successful, but a person can ruin a barrel if done incorrectly. Only you can determine if you feel comfortable doing it yourself..A lot of bubbas in the world working on rifles with dremel tools you need to stay far away from..Last edited by montana; 12-20-2022, 05:56 PM.Comment
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I can clearly see where the damage on the bullet tip came from on your barrel extension. The hard line across the tip and the copper spot on your barrel extension. Take it to a gunsmith that wants to do it. Some gunsmiths only want to work on bolt actions, and are very dismissive of AR15's. From an hourly cost perspective I'd say 1 hour to take apart and reassemble, and 1 hour for the work. Give the gunsmith some dummy rounds and crimp them hard so he can cycle the action.
Also, take a picture of your bolt face and post it.Comment
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Cratex https://www.brownells.com/gunsmith-t...ku=190-025-081, Polish-O-Ray 555 grey https://www.brownells.com/gunsmith-t...prod24792.aspx https://www.brownells.com/gunsmith-t...839-500-025You will be doing better than most using just these two types..Originally posted by bmash View Post
Some people will polish the bolt face, but be careful as it will change the head space. Others will modify the extractor, lap the barrel lugs to the barrel extension (that will also effect head space) and other personal tweaks..Comment
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NRA Basic, Pistol, Rifle, Shotgun, RSO
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
www.AR15buildbox.comComment
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Originally posted by bmash View Post
Try chambering (from a magazine) a round as slow as possible a few times. Notice how the back end of the case has to slide across the bolt face? A rough bolt face, or a plunger with sharp edges can cause problems.
Plunger edges should be rounded; looks like yours is rounded.
Lightly polish the face of the two lugs that push the case out of the magazine. Just use Flitz and a wool felt Dremel cylinder. You are just smoothing / polishing.
Aim-Surplus-Bolt-Carrier-2.jpg
What's going on with your lugs? Is the metal chewed up? Looks really rough.
61F347A2-CD9C-4229-A614-5CD00CB237F0 (1).jpegComment
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