My DA556 is jamming, need help.

[Sqr]

Yes, see post #19


I was experiencing the same problem when I replaced the entire BCG from my M4gery. The 14.5" runs fine.

One thing I never mentioned is my rifle flings the brass hard to the 5 o'clock position. The rifle doesn't have a brass deflector and if a lefty shot it they would constantly have brass thrown in their face. I did a quick search on the internet and this seems to suggest that the rifle is over-gassed. Anyone know where I can get a replacement rifle buffer? Are there heavier models for rifles that might slow down the cyclic rate?

I scrubbed the chamber to make sure it's clean and tried to take a picture of the feed ramps.

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No M4 feed ramps can lead to deformation of the cartridge brass when chambered creating poor case to chamber fitment. It appears there may be a shiney lip on the left side of the receiver from the cartridge lip peeling back. This could be wedging the case into the throat restricting the extraction. A Dremel tool can be used to modify the receiver by adding the missing feed ramps.

 

[TW25B]

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No M4 feed ramps can lead to deformation of the cartridge brass when chambered creating poor case to chamber fitment. It appears there may be a shiney lip on the left side of the receiver from the cartridge lip peeling back. This could be wedging the case into the throat restricting the extraction. A Dremel tool can be used to modify the receiver by adding the missing feed ramps.

Uhh.. Absolutely not correct at all, and dremeling in your own ramps is retarded. Please don't give wrong advice and dangerous advice..

TW25B

 

[Sqr]

It appears you have what is called a rifle barrel extension that doesn't require M4 receiver ramps. However the fitment between the two must be percise so there is no ridge on the receiver which can damage brass.

Here are a few examples of cartridges scored or creased by feed ramp issues when receivers and barrel extension are void of smooth loading paths. If they are hammered into a chamber they may stick and creat FTE's or FTF's.

This damage can be a possible symptom of the magazine not being completely insterted into the mag well due to mag rivets or sloppy mag locks. If the alignment has changed the transition between the magazine and chamber forces the cartridge to drag up the receiver face when driven into battery.

Polishing ramps, receivers and lugs is quite common and can be successful in competent hands.

 

[TW25B]

It appears you have what is called a rifle barrel extension that doesn't require M4 receiver ramps. However the fitment between the two must be percise so there is no ridge on the receiver which can damage brass.

Here are a few examples of cartridges scored or creased by feed ramp issues when receivers and barrel extension are void of smooth loading paths. If they are hammered into a chamber they may stick and creat FTE's or FTF's.

This damage can be a possible symptom of the magazine not being completely insterted into the mag well due to mag rivets or sloppy mag locks. If the alignment has changed the transition between the magazine and chamber forces the cartridge to drag up the receiver face when driven into battery.

Polishing ramps, receivers and lugs is quite common and can be successful in competent hands.

Sorry, but still wrong. The two creased cartridges are from the bolt crushing the case against the barrel extension, a result of a failure to feed which is usually caused by worn out/out of spec magazines(specifically the feed lips). The top two cartridges have some scrape marks from loading which is fairly normal and not an issue. The firing sequence is a violent operation, there will be scratches on the brass and the projectile.

M4 feed ramps are not necessary for the rifle to function. The M4 feed ramps were introduced to reduce the potential for stoppages when the M4 was being fired(specifically in full auto) due to the over gassing of the carbine gas system the bolt velocities were very high, making the loading sequence more violent than it already was.

http://www.ar15barrels.com/gfx/feedramps.jpg

If your magazine is not seated it will(and should) fall out or not feed as it will be sitting too low for the bolt to strip a round.

Polishing anything on any firearm to get it to run properly is a sign of a broken gun. If it doesn't run out of the box, it is broke or a lemon. A mil spec AR needs nothing but lube and ammo to run. Seeing as how the OP had this rifle running without issue, is an indication that the feed ramps or lack thereof have nothing to do with his issues. The OP is experiencing double feeds due to spent brass not being ejected which is a failure to eject problem, neither the double feed nor the FTE have anything to do with feed ramps.


TW25B

ETA: Here's a great explanation of what is going on and what the problem is.

http://www.ar15barrels.com/prod/operation.shtml

 

[0.5moa]

check headspace, check to make sure your gas system is working properly by making sure the bolt stays open on a single round. If all is good , then i would look into overgasing or weak buffer spring. Try someone elses bcg or just the bolt, and if all fails then i would suggest changing the barrel.

 

[compass]

edited post.