View Full Version : Marks On Expelled Brass Casings?
I noticed the last time I was at the range, that my all my expelled casings have a mark ( more like a tiny crease ), a little better than half way down.
Is this supposed to happen? If not... what would cause this to happen?
Hmm... can see the detail too well from your photo. How deep is the dent?
Could it be just a dent caused by the brass deflector?
lawusmc0844
01-29-10, 19:09
I've been wondering the same thing because my BCM BFH upper causes the exact same mark around the same location.
Hmm... can see the detail too well from your photo. How deep is the dent?
Could it be just a dent caused by the brass deflector?
Sorry for the bad pics, the lighting was killing me.
It's not really that deep, but it's enough to feel it with you're fingernail.
I guess it could be the deflector, I was more concerned with the rifle not funtioning properly.
I also plan on reloading in the future, so I didn't know if that mark would prevent me from using the brass. :confused:
Dont worry about the photo. Had a brass issue in the past and it took me forever just to get one that remotely showed any detail. :D
HAve you cleaned off your upper already? Maybe you could take photos of the rear section of the ejection port and the brass deflector? It may shed some light as to where it might be hitting.
BTW, could you give us your specs? Upper Assy, BCG, Spring, Buffer weight etc...?
BTW, could you give us your specs? Upper Assy, BCG, Spring, Buffer weight etc...?
No problem, I'm running a BCM middy with a BCM BCG, lower is a CMMG with a standard spring and buffer.
I try to clean it after every trip to the range, which is 1 or 2 times a month lately. ( about 50 rounds per trip )
I only have about 300-400 rounds through the rifle total so far.
I have a BCM middy that used to do the exact same thing when I first received it. The casings were hitting the leading edge of the deflector, very close to the ejection port, where it's sharp. I could tell because the anodizing wore off the deflector at that spot.
I was originally using a carbine buffer, and my brass was being ejected forward, between 1 and 2 o'clock. I switched to an H buffer, and now all my brass ejects between 3 and 4 o'clock, and the dents midway down the casings are no longer present. You can also see that the brass hits the middle of the deflector, instead of the sharp point near the ejection port.
For comparison sake my rifle is entirely BCM and has about 1200 rounds through it, 1000 of which are with the H buffer, and zero malfunctions.
As others recommend, just make sure that your bolt locks back consistently on the last round with your weakest ammo if you start using heavier buffers.
organdonor
01-29-10, 21:43
i bought some m855 ss109 from cheaperthandirt and most of the casings have dents like that.
I have a BCM middy that used to do the exact same thing when I first received it. The casings were hitting the leading edge of the deflector, very close to the ejection port, where it's sharp. I could tell because the anodizing wore off the deflector at that spot.
+1! Forget the pics I asked for. :D
Seen those on occasion but I'd like to know why I'm getting extractor imprints on the case rim with Prvi 5.56mm.
lanceriley
01-30-10, 08:02
it's probably nothing... try changing buffers. if it disappears it's probably how it's impacting the deflector
+1! Forget the pics I asked for. :D
I will take some and post them this morning.
Here you go, I highlighted where I could see brass markings. I did notice the brass eject between the 1 and 2 o'clock range the last time I was out.
Can't say what is causing it or not, but the crease should not affect your reloading at all. Much of the surplus brass I purchase for reloading has dents like this.
The first picture is just like my rifle, which is exactly where my brass was hitting until I used a heavier buffer. It's caused by your bolt moving just a bit too fast. If you slow it down the brass will hit the broad section of the deflector, and have a more normal ejection path.
Looks like I have to pick up an H buffer, thank's for the help guy's.
What's your current config? - Barrel length, gas system, buffer weight and BCG?
Saw your pics and seems like Slippers is right on... Can you post your current specs?
I posted my specs above, upper is a standard BCM middy with a FA BCG and the lower is a CMMG with standard buffer.
Just an update, I ordered a H buffer from Grant and received it the other day. I went to the range today and had the same results with the brass as originally stated. :confused:
Blankwaffe
02-15-10, 19:36
Are you running a crane o-ring under the extractor?
If so remove the o-ring and see what it does.
I had all kinds of odd issues running the o-ring in my middies, and early on(before I knew better) in rifle length uppers during my BCG upgrades.As a note I dont run the orings in my LMT 16" carbine upper either.
The heavy extractor tension created by the o-rings will also cause the extractor claw to chew the case rims up a bit at times as well.
Heavy Metal
02-15-10, 19:41
That mark is not abnormal. I would not sweat it for a second.
Are you running a crane o-ring under the extractor?
If so remove the o-ring and see what it does.
I had all kinds of odd issues running the o-ring in my middies, and early on(before I knew better) in rifle length uppers during my BCG upgrades.As a note I dont run the orings in my LMT 16" carbine upper either.
The heavy extractor tension created by the o-rings will also cause the extractor claw to chew the case rims up a bit at times as well.
I never installed a crane o-ring, do BCM bcg's come with them installed?
That mark is not abnormal. I would not sweat it for a second.
Thats good to know, I just wanted to make sure it had nothing to do with the rifle function.
arizonaranchman
02-15-10, 22:39
Are you running a crane o-ring under the extractor?
If so remove the o-ring and see what it does.
I had all kinds of odd issues running the o-ring in my middies, and early on(before I knew better) in rifle length uppers during my BCG upgrades.As a note I dont run the orings in my LMT 16" carbine upper either.
The heavy extractor tension created by the o-rings will also cause the extractor claw to chew the case rims up a bit at times as well.
Thanks for the O ring tip... I think you just solved one of my dilemmas - a slightly chewed case rim by the extractor. I'll remove my O ring on my BCM BCG and see if that does it!
check your action spring length.. bad springs aren't super uncommon.
Blankwaffe
02-15-10, 23:51
Thanks for the O ring tip... I think you just solved one of my dilemmas - a slightly chewed case rim by the extractor. I'll remove my O ring on my BCM BCG and see if that does it!
Yeap,the BCM extractor springs are super heavy duty by themselves and do not need the o-ring for most in my experience.
To be truly honest I actually prefer the standard Colt carbine extractor spring and black insert for my middies and rifle length uppers.
Blankwaffe
02-15-10, 23:59
I never installed a crane o-ring, do BCM bcg's come with them installed?
My BCM BCG came with the o-ring packaged seperate from the assembly.But it would be worth taking a minute and pulling the extractor to check and see if its in place.
Ive yet to see a need for the o-ring and routinely pull them from my LMT,DD etc. BCG's that did come with them installed.That said I do not have any SBR's either,so my need is limited to 16" and 20" barrel upper configurations.
My BCM BCG came with the o-ring packaged seperate from the assembly.But it would be worth taking a minute and pulling the extractor to check and see if its in place.
Ive yet to see a need for the o-ring and routinely pull them from my LMT,DD etc. BCG's that did come with them installed.That said I do not have any SBR's either,so my need is limited to 16" and 20" barrel upper configurations.
I checked the bolt last night and no o-ring, but now that you mentioned it, I do remember seeing an o-ring when I recieved my bcg.
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