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Posted: 1/12/2006 7:32:06 PM EDT
A friend of mine just got an AR (actually, I got him the damn thing) w/ M4 cuts. When chambering a round the gun leaves a pretty nice gash down the side of the bullet (doesn't matter which side of the mag it's feeding from.) It seems to bother him, hell, it bothers me.
This isn't a light mark, it's a gash...

I spoke to a 'smith and he said to take a rat-tail and gently break the edge(s) of the center lug ( ? hey, I don't know what you call it, the pointy things) The center one between the cuts seems to be the culprit.

Anyone thing this is a really bad idea ? Anyone think this problem effects accuracy since the bullet is coming out with this freakin' gash down it's side ?

Thanks
Link Posted: 1/12/2006 7:37:50 PM EDT
[Last Edit: 1/12/2006 7:38:45 PM EDT by theshootersden]
I wouldn't just use a rat tail file, I would wrap a piece of emery cloth around the file or wrap the emery cloth around a small wooden dial rod and polish the areas in question...

But what you are describing could be caused by the magazine too... Did you try different brand mags to see if it still did it?

ETA: Also inspect the chamber for any burrs...
Link Posted: 1/12/2006 7:40:34 PM EDT
[Last Edit: 1/12/2006 7:41:05 PM EDT by Dog1]
My White Oak SPR barrel did that. I took some fine emery cloth and light ran it over the center lug...no more scratches....
Link Posted: 1/13/2006 6:24:47 AM EDT
Yep, tried it with my magazines, same thing.

Thank you for the advice on the emory cloth... Any advice on what roughness to use and where to get it locally ? I don't feel like making a special order just for some emory cloth.

Thanks again
Link Posted: 1/13/2006 6:29:26 AM EDT
I have a similar problem, but my question to the balistics guru's is will it actually cause a change in bullet flight? Just from my standpoint I doubt it so I wont do anything to change it unless I learn otherwise. I have a feeling it will probably be erased as the bullet makes contact at high speed with the chrome of the barrel and rifling.
Link Posted: 1/13/2006 6:30:19 AM EDT
My Oly does the same thing. It leaves a "twisting line" cut on the bullet as the round is rotated as it's being chambered. That can't be good on the barrel or help out with accuracy. I need to try to do some smoothing out also.

Can someone post a picture showing the exact areas that I should smooth out?

Thanks
Link Posted: 1/13/2006 6:34:16 AM EDT
[Last Edit: 1/13/2006 6:35:28 AM EDT by QUIB]

Friend's AR leaving drag mark on his bullet... Can I take a rat-tail file to it ?



Sure can! I polish all my bullets with a file, makes em' real perty and shiney!

Sorry, I just had to. That topic subject was just asking for it!
Link Posted: 1/13/2006 6:39:35 AM EDT
[Last Edit: 1/13/2006 6:43:59 AM EDT by eye_spy]
...or go to the hardware and find the finest grit sand paper there is for metal / iron .... tear a small piece of it and just slowly rub it on the sharp edge of the lug / ramp or whatever part was causing the gash ...
Link Posted: 1/13/2006 6:40:39 AM EDT
[Last Edit: 1/13/2006 6:46:38 AM EDT by theshootersden]

Originally Posted By bloodsport2885:
I have a similar problem, but my question to the balistics guru's is will it actually cause a change in bullet flight? Just from my standpoint I doubt it so I wont do anything to change it unless I learn otherwise. I have a feeling it will probably be erased as the bullet makes contact at high speed with the chrome of the barrel and rifling.



All you want to do is polish the barrel extension lug (the one between the ramps) to remove the sharp edges, no changes will be made to the accuracy of the barrel...

You do NOT want to use a file or emery cloth on the chamber or bore, that would cause accuracy problems...
Link Posted: 1/13/2006 6:43:05 AM EDT

Originally Posted By AcidGambit:
Yep, tried it with my magazines, same thing.

Thank you for the advice on the emory cloth... Any advice on what roughness to use and where to get it locally ? I don't feel like making a special order just for some emory cloth.

Thanks again



Your local hardware store should have it... Use the smallest grit available...
Link Posted: 1/13/2006 6:48:27 AM EDT
I have used 2000 grit sand paper from Wal Mart to fix this exact problem. It can be found in the automotive section where the touch up paint and other car body supplies are. Wrap a small piece around a bullet and polish the corners of the lugs on either side of the feed ramps. The problem is they are sharp and cutting into the bullet when feeding.
Link Posted: 1/13/2006 8:29:34 AM EDT
How do you know this? Do you fly like Superman next to the bullet and watch it in flight? Nope you eject the chambered round and drag the bullet acraoss the lugs gouging the bullet after its extracted. Why do you care that the bullet is gouged when ejected if its not gouged when fired? I thought my barrel was doing this too when ejecting rounds when I first got an AR till I realised it was the ejection of the bullet that caused he gouge, not the loading.
Link Posted: 1/13/2006 9:07:26 AM EDT

Originally Posted By DevL:
How do you know this? Do you fly like Superman next to the bullet and watch it in flight? Nope you eject the chambered round and drag the bullet acraoss the lugs gouging the bullet after its extracted. Why do you care that the bullet is gouged when ejected if its not gouged when fired? I thought my barrel was doing this too when ejecting rounds when I first got an AR till I realised it was the ejection of the bullet that caused he gouge, not the loading.



Damn dude, never though about that... great point !!!

All I know is that mine don't do it and his does... Mine have many more rounds through them though.
Link Posted: 1/13/2006 9:34:27 AM EDT

How do you know this? Do you fly like Superman next to the bullet and watch it in flight? Nope you eject the chambered round and drag the bullet acraoss the lugs gouging the bullet after its extracted. Why do you care that the bullet is gouged when ejected if its not gouged when fired? I thought my barrel was doing this too when ejecting rounds when I first got an AR till I realised it was the ejection of the bullet that caused he gouge, not the loading.



After I chamber and eject the round, I have looked at the bullet through big magnifying glass. I can tell by looking at the cut in the bullet that the metal is being pushed BACK as it's being chambered. Pretty cool actually.

So when it comes to my rifle...I know it's doing it on the way in....not the way out
Link Posted: 1/13/2006 9:55:08 AM EDT

Originally Posted By theshootersden:

Originally Posted By bloodsport2885:
I have a similar problem, but my question to the balistics guru's is will it actually cause a change in bullet flight? Just from my standpoint I doubt it so I wont do anything to change it unless I learn otherwise. I have a feeling it will probably be erased as the bullet makes contact at high speed with the chrome of the barrel and rifling.



All you want to do is polish the barrel extension lug (the one between the ramps) to remove the sharp edges, no changes will be made to the accuracy of the barrel...

You do NOT want to use a file or emery cloth on the chamber or bore, that would cause accuracy problems...



I was talking about the marks left in the jacket of the bullet causing each round to have a unique flight pattern instead of a more consistant one.
Link Posted: 1/13/2006 1:24:23 PM EDT
I had the same issue with a number of rifles. I tried fixing it with a dremmel. Worked pretty ok, but there was still a slight scratch in the jacket after chambering. Was never a really big deal. Is the rifle acceptably accurate?


-K
Link Posted: 1/13/2006 1:32:43 PM EDT
[Last Edit: 1/13/2006 1:34:08 PM EDT by MadDogDan]
Are you talking about scratches or marks in the bullet or the shell casing? If you are talking about the bullet, how do you know the marks are not caused by a nick in the rifling? Or a nick in the muzzle crown? And how are you retrieving the bullets after they have been fired? Sounds to me like you are talking about the casings. Bullet = projectile, bullet sits in casing & together they = a round. Which is it?

MadDog
Link Posted: 1/13/2006 1:47:24 PM EDT

Originally Posted By DevL:
How do you know this? Do you fly like Superman next to the bullet and watch it in flight? Nope you eject the chambered round and drag the bullet acraoss the lugs gouging the bullet after its extracted. Why do you care that the bullet is gouged when ejected if its not gouged when fired? I thought my barrel was doing this too when ejecting rounds when I first got an AR till I realised it was the ejection of the bullet that caused he gouge, not the loading.





You must have some wierd big ass lugs on your AR. Because on mine the front end of the casing is perfectly centered when attached to the bolt and doesnt even come close to any lugs.

On a more serious note, to the original poster, if you want to see what exactly is hitting the bullets before going in and filing everything down, put a little marking compound (crayon, white putty, actual marking compound, anything you are sure you can get out of the chamber with a brush afterwards) on the bullet tips, maybe 3 or 4, and manually cycle the gun. You will then see on the receiver where the bullet is striking. Just make sure you clean out your chamber after doing this to get the marking compound out.
Link Posted: 1/13/2006 1:52:33 PM EDT

Originally Posted By MadDogDan:
Are you talking about scratches or marks in the bullet or the shell casing? If you are talking about the bullet, how do you know the marks are not caused by a nick in the rifling? Or a nick in the muzzle crown? And how are you retrieving the bullets after they have been fired? Sounds to me like you are talking about the casings. Bullet = projectile, bullet sits in casing & together they = a round. Which is it?

MadDog



Dude, think... I am manually ejecting the round.
Link Posted: 1/13/2006 1:53:45 PM EDT
[Last Edit: 1/13/2006 1:56:03 PM EDT by AcidGambit]

Originally Posted By Dace:

Originally Posted By DevL:
How do you know this? Do you fly like Superman next to the bullet and watch it in flight? Nope you eject the chambered round and drag the bullet acraoss the lugs gouging the bullet after its extracted. Why do you care that the bullet is gouged when ejected if its not gouged when fired? I thought my barrel was doing this too when ejecting rounds when I first got an AR till I realised it was the ejection of the bullet that caused he gouge, not the loading.





You must have some wierd big ass lugs on your AR. Because on mine the front end of the casing is perfectly centered when attached to the bolt and doesnt even come close to any lugs.

On a more serious note, to the original poster, if you want to see what exactly is hitting the bullets before going in and filing everything down, put a little marking compound (crayon, white putty, actual marking compound, anything you are sure you can get out of the chamber with a brush afterwards) on the bullet tips, maybe 3 or 4, and manually cycle the gun. You will then see on the receiver where the bullet is striking. Just make sure you clean out your chamber after doing this to get the marking compound out.



Definately the center tooth/lug... I can see the copper streak on it.

To the guy who asked about the accuaracy of the rifle, I don't know, I haven't shot his gun.

I'm going to print this out and give it to him. If he wants to emory the thing, fine, it's his gun.

Maybe I'll get a loaf of white bread, shoot a round into it and recover the bullet, see if the gash is there.
Link Posted: 1/13/2006 3:01:30 PM EDT
A loaf of white bread? I f that wasn't a joke could I please have some of what ever it is your smoking?
Link Posted: 1/14/2006 5:57:49 AM EDT
[Last Edit: 1/14/2006 5:58:25 AM EDT by AcidGambit]

Originally Posted By outguy:
A loaf of white bread? I f that wasn't a joke could I please have some of what ever it is your smoking?



Dude, it was a joke... hence all the smiley faces after the remark.

Besides, everyone knows that only wheat bread will stop bullets.
Link Posted: 1/14/2006 7:53:44 AM EDT
What you want to do is "polish" the offending area. Files don't polish! Using a Dremel tool is OK if, and that is a BIG if, you use a polishing felt cone and a fine grade of jewlers rouge AND are very careful, not agressive. Dremels cut real quick and shit happens.

IMHO, the wooden dowel or a wooden pencil is best as you can't apply too much pressure that may result in "over correcting" the problem and creating a new one. The finest grade of automotive wet/dry paper is what you should use, or "crocus" cloth. Polish, test, polish, test... See the pattern?
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