gondo Posted February 18, 2014 Share Posted February 18, 2014 My rifle is running perfect for a few hundred rounds of various ammo, as i attempt to get it completely dialed in for 3 gun season can some of you look at my brass and tell me what you see. I dont see any signs of pressure problems but i do see a couple of marks im wondering about since this is my only semi auto rifle. First is the marks from the extractor on the back of the case... from looking at others brass they look about like everyones to me. Then the next pics are abvious feed marks i believe. Im guessing the dents in the shoulder are from the case hitting the ramps on the way in the chamber? and the 2 line marks on the neck are from the sharp new ramps on my new barrel?? Sorry this is the best i could do with the pics. Link to comment Share on other sites More sharing options...
michael1778 Posted February 18, 2014 Share Posted February 18, 2014 Dents like in image #3 must be after being fired, not before. I say that because many people "fire form" brass for unusual cartridges by feeding undersized or differently shaped cases into their rifle chamber, then firing the ammo, and reusing the explosively formed cases. A dent in a case should not survive being fired unless it was monstrous at the start. And if so you'd get odd burning, most likely. I don't have enough experience with rifle mechanics to diagnose the issues, but the image with the dents must be something after being fired. Dents before ignition would not remain. They would be explosively formed out. Link to comment Share on other sites More sharing options...
Nebwake Posted February 18, 2014 Share Posted February 18, 2014 (edited) What rifle? I have seen those shoulder dents on M-4's quite often. does it do it on every round? Edited February 18, 2014 by Nebwake Link to comment Share on other sites More sharing options...
gondo Posted February 18, 2014 Author Share Posted February 18, 2014 ar15 with m4 feed ramps, its all factory xm193, the dents were done during feeding or firing... no other way they got there Link to comment Share on other sites More sharing options...
gondo Posted February 18, 2014 Author Share Posted February 18, 2014 What rifle? I have seen those shoulder dents on M-4's quite often. does it do it on every round? yes Link to comment Share on other sites More sharing options...
Scott Steele Posted February 18, 2014 Share Posted February 18, 2014 I thought those type dents were from the brass deflector on most uppers. Link to comment Share on other sites More sharing options...
gondo Posted February 18, 2014 Author Share Posted February 18, 2014 I thought those type dents were from the brass deflector on most uppers. hadnt thought of that... anyone else think that is right? Link to comment Share on other sites More sharing options...
michael1778 Posted February 18, 2014 Share Posted February 18, 2014 ar15 with m4 feed ramps, its all factory xm193, the dents were done during feeding or firing... no other way they got there By "after firing", I mean after the moment of ignition in the chamber. Something in the extraction process. I didn't mean while the spent case was sitting on the ground. :-) Link to comment Share on other sites More sharing options...
Ming the Merciless Posted February 18, 2014 Share Posted February 18, 2014 The dents are from the case hitting the case deflector during ejection. Look at the deflector and you'll see brass marks. If the dent were further down the case it would be from the case hitting the edge of the ejection port. Link to comment Share on other sites More sharing options...
gondo Posted February 18, 2014 Author Share Posted February 18, 2014 ar15 with m4 feed ramps, its all factory xm193, the dents were done during feeding or firing... no other way they got there By "after firing", I mean after the moment of ignition in the chamber. Something in the extraction process. I didn't mean while the spent case was sitting on the ground. :-) i got ya... could be Link to comment Share on other sites More sharing options...
gondo Posted February 18, 2014 Author Share Posted February 18, 2014 The dents are from the case hitting the case deflector during ejection. Look at the deflector and you'll see brass marks. If the dent were further down the case it would be from the case hitting the edge of the ejection port. cool im gonna put something soft like felt on the deflector and if it goes away that will be proof.... Link to comment Share on other sites More sharing options...
MickB Posted February 18, 2014 Share Posted February 18, 2014 None of my AR's dents brass like that. If it is caused by the shell deflector, then it is extracting pretty hard, which could mean overgassing or too light a buffer. What barrel length and gas system? Carbine? Mid-length? Rifle? Mick Link to comment Share on other sites More sharing options...
cas Posted February 19, 2014 Share Posted February 19, 2014 No…. that lower doesn't make your brass look big. Link to comment Share on other sites More sharing options...
gondo Posted February 19, 2014 Author Share Posted February 19, 2014 None of my AR's dents brass like that. If it is caused by the shell deflector, then it is extracting pretty hard, which could mean overgassing or too light a buffer. What barrel length and gas system? Carbine? Mid-length? Rifle? Mick It's not over gassed, I know that for fact Link to comment Share on other sites More sharing options...
gondo Posted February 19, 2014 Author Share Posted February 19, 2014 No. that lower doesn't make your brass look big. Lmao... Link to comment Share on other sites More sharing options...
67camaro Posted February 20, 2014 Share Posted February 20, 2014 Does your new barrel have a rifle extension and your upper m4 ramps? This could be happening during feeding. Drop a few from a locked back bolt extract and check. Link to comment Share on other sites More sharing options...
billdozer Posted February 21, 2014 Share Posted February 21, 2014 Turn your gas down if you have an adjustable gas block. If not try to rotate your gas block just a little to the side, to eliminate the overgassing theory. Link to comment Share on other sites More sharing options...
gondo Posted February 21, 2014 Author Share Posted February 21, 2014 Actually I'm kind of embarrassed to say that I don't think that was my brass, I shot 200 rnds yesterday and know for a fact I got my brass back and not a hint of this anywhere... All I can figure is that my father in law put this in my spent brass bag while we were shooting Idpa, it's the same place we shoot 3 gun and he was dumping brass in my bag all day... Sorry to waste time it appears... Link to comment Share on other sites More sharing options...
GreenDragon64 Posted February 21, 2014 Share Posted February 21, 2014 Well, if you're still concerned about the brass being damaged, I'll meet you in Chattanooga and I'll reload them and test out the cases. Link to comment Share on other sites More sharing options...
gondo Posted February 21, 2014 Author Share Posted February 21, 2014 Well, if you're still concerned about the brass being damaged, I'll meet you in Chattanooga and I'll reload them and test out the cases. You from nearby? Shoot at chrpc? Link to comment Share on other sites More sharing options...
GreenDragon64 Posted February 21, 2014 Share Posted February 21, 2014 Yes, Fort Payne. I know 2 from around Chattanooga from them shooting at a 3GN range I frequent. They have mentioned shooting at that range. Link to comment Share on other sites More sharing options...
ShooterSteve Posted February 22, 2014 Share Posted February 22, 2014 Dents like that are NOT caused during feeding. Michael is correct in stating that brass gets blown out during firing. It will match your chambers interior profile. That is how you form brass for an ackleyized round. If the pressure will blow out an entire shoulder, little dents like those would be ironed out instantly. Once the rifle fires, that stuff is coming out in a hot and violent manner, and that is when stuff gets dinged up. Ask your FIL if he was stepping on them to dent them and then putting them in your bag to mess with you! Link to comment Share on other sites More sharing options...
38superman Posted February 23, 2014 Share Posted February 23, 2014 (edited) I've seen this before, but never in a factory round. Sometimes under very specific circumstances, a fired round doesn't generate sufficient pressure to expand the neck properly and get a good seal against the wall of the chamber. This allows a small amount of gas to seep around the neck and bleed back into the chamber between the brass and the chamber wall. This can cause the type of dents you are seeing. I had this issue years ago in a 30-06 shooting IMR 4064. There is absolutely no flattening of the primer. Except for the firin pin indention, they look pristine. Judging from the photo, I'd say these rounds are producing relatively low peak pressure. I could be way off base but It's just a thought. Tls Edited February 23, 2014 by 38superman Link to comment Share on other sites More sharing options...
gondo Posted February 24, 2014 Author Share Posted February 24, 2014 I've fired another 300 rounds and not seen any of this so I'm gonna have to stick with this probably wasn't mine Link to comment Share on other sites More sharing options...
Iowashooter Posted March 2, 2014 Share Posted March 2, 2014 My necks get dented similarily, and a few times behind the shoulder, they usually pop out when I size them other wise they get fire formed. Sent from my SCH-I545 using Tapatalk Link to comment Share on other sites More sharing options...
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