Strange Feeding issue

[ShrockWorks]

New build. .204 Ruger if it matters. It is the same diameter case as a .223, but the neck is pushed forward a bit.

I cant get it to feed feed even one round from a magazine. Ok it will occasionally feed one or two out of 5 or 10, but it sounds bad and the case get damaged on the bottom side.

.204 Ruger in an AR uses std .556 mags just fine by all accounts I've read. I have tried several different magazines and different types of magazines. It will do this this with only one round loaded in the mag. I am fairly certain it is not a magazine issue.

The case is already in the chamber when the bolt stops moving forward.

The plastic tips on the Vmax bullets look unmolested.

Pics of where it hangs, same spot every time.

http://i303.photobucket.com/albums/nn127/shrockworks/Guns%20and%20Hunting/IMG_0877.jpg

http://i303.photobucket.com/albums/nn127/shrockworks/Guns%20and%20Hunting/IMG_0876.jpg

http://i303.photobucket.com/albums/nn127/shrockworks/Guns%20and%20Hunting/IMG_0875.jpg

http://i303.photobucket.com/albums/nn127/shrockworks/Guns%20and%20Hunting/IMG_0874.jpg

http://i303.photobucket.com/albums/nn127/shrockworks/Guns%20and%20Hunting/IMG_0873.jpg

Pics of what the case looks like after. Major smiley face dent in the brass.

Top one: Got stuck
Middle one: Fed, barely, but damaged.
Bottom one: normal for comparison.

http://i303.photobucket.com/albums/nn127/shrockworks/Guns%20and%20Hunting/IMG_0879.jpg

Feeding a round into the chamber with my fingers, with the upper off, pushing the brass against the bottom edge of the chamber, the chamber edge feels very sharp. It really grabs the brass and scratches it, even with only modest pressure. Pic:

http://i303.photobucket.com/albums/nn127/shrockworks/Guns%20and%20Hunting/IMG_0881.jpg

I tried the same thing with some of my other uppers in different calibers, and they did not grab and scratch the brass the same way.

I'm thinking the barrel is my problem and that the chamber edges are too sharp. Thoughts?

The barrel is a 24" Shilen .204 Ruger FWIW.

[vicious_cb]

New build. .204 Ruger if it matters.



If it an odd ball caliber for an AR then yes it matters.

[AKDoug]

If the chamber marks brass like that with just finger pressure, I would wager that is your issue. Did you full length resize your brass?

[5pins]

The first thing you should try is turning in the mag catch until it is flush or slightly past the button.

http://generalcartridge.net/images/IMG_0873.jpg

[BrigandTwoFour]

FWIW, that could be a bullet button to make the rifle not evil in CA.


I've had similar malfunctions with .223 ammo, where the case gets partially fed than then the bolt hammers it against the feed ramp. Not entirely sure what the problem is, but my guess is underpowered ammo combined with a heavy buffer on a cold day.

[ShrockWorks]

If the chamber marks brass like that with just finger pressure, I would wager that is your issue. Did you full length resize your brass?
Thanks AK Doug,

I'm using factory Hornady ammo for this testing. I dont have all my .204 reloading stuff yet.

40gr pills with the same BC as a 60gr .223 Nosler Ballistic Tip, but they leave the muzzle at at 3900 FPS. :D

[constructor]

Case rim is getting hung up on ejector or extractor or both.
Take a dremel and grind a small bevel on the inside edge of the ejector pin. Then if the extractor is sticking out past the face of the bolt, sand it smooth.

One other thing you can try to make the release from the mag smoother if you have an old one to experiment with is to round off the front corner of the feed lip(about 1/4" radius). It allows the rim of the case to start coming up a little at a time rather than popping up all at once when it gets to the front of the feed lip. I wouldn't do it on a combat rig but a mag or 2 to shoot varmints or targets doesn't take too long.

[ShrockWorks]

Case rim is getting hung up on ejector or extractor or both.
Take a dremel and grind a small bevel on the inside edge of the ejector pin. Then if the extractor is sticking out past the face of the bolt, sand it smooth.

One other thing you can try to make the release from the mag smoother if you have an old one to experiment with is to round off the front corner of the feed lip(about 1/4" radius). It allows the rim of the case to start coming up a little at a time rather than popping up all at once when it gets to the front of the feed lip. I wouldn't do it on a combat rig but a mag or 2 to shoot varmints or targets doesn't take too long.

I'll try a different bolt I know works.


Anyone else have any thoughts?