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riverwalker76
April 3, 2010, 03:19 PM
I'm having problem with my new AR15. Most of the time it will not fully load a cartridge.

If I fire the rifle with 1 cartridge in the mag it does engage the bolt stop, so short stroking isn't a problem.

My problem is that when the Bolt Carrier Group charges the next round it will leave it half-way out of the chamber and the BCG will not go to Full Battery. In other words ... if I look at the ejection port I see a cartridge that is half way out, and the BCG is there in the half position.

Here is what it is doing to my brass. Any suggestions will be appreciated.


http://i363.photobucket.com/albums/oo78/AntlerandStone/DSC01137.jpg

rjrivero
April 3, 2010, 03:46 PM
What Magazines are you using?

Try a different Magazine or two. Most malfunctions of this type are magazine related.

I've also seen this kind of failure due to an accuwedge between the upper and lower trying to remove the "play" between the upper and lower.

Essentially you're putting more gap between the carrier and the magazine causing issues stripping the next round from the mag and getting hung up as it tries to feed.

You also want to check your magazine catch for abnormal wear.

riverwalker76
April 3, 2010, 03:52 PM
Don't use an accuwedge.

I've tried two different magazines. Colt & DPMS

Magazine catch shows no wear.

Scorch
April 3, 2010, 04:17 PM
Is that reloaded once-fired brass? It sure looks like it. Small base dies are the answer, if so.

riverwalker76
April 3, 2010, 04:20 PM
No. It's Federal Mil-Spec 55 gr. FMJ with Crimped Primers.

Scorch
April 3, 2010, 04:22 PM
Check out the chamber, then. It looks like it's tight around the mouth of the chamber.

HiBC
April 3, 2010, 06:03 PM
When I cut a chamber,after it is roughed to near finish depth,I scrape,stone polish a small radius to break the sharp edge at the chamber mouth.The rounds do have to turn around that corner a bit as the feed.If it is sharp,it can cut into the brass,as it seems yours is doing.
Now,it is also possible mag feed lips or something silly like a fouled ejector plunger are involved.I'd check all that out before getting excited.

But it may be necessary to break the sharp edge off the chamber,if it is sharp enough to cut brass.

It is one of those things a person who does not know quite what they are doing can mess up very badly.

riverwalker76
April 3, 2010, 06:55 PM
The edges are fairly sharp. Here is a pic of where the feedramp meets the receiver. Tell me what you think. How do I fix this?

Also, would this prevent it from reaching Full Battery?


http://i363.photobucket.com/albums/oo78/AntlerandStone/DSC01143.jpg

highvel
April 3, 2010, 08:21 PM
The area that shows abrasion go all the way around the case?
From what I see in the picture the case could be a slight bit oversized for the chamber. My $.02

riverwalker76
April 3, 2010, 09:56 PM
The case is the first firing. New bullets generally aren't oversized.

Gunplummer
April 4, 2010, 12:21 AM
I'm with Scorch and HiBc, you can get this on bolt guns if there is a sharp burr where the chamber starts. It is rare, but a extra tough extractor spring will do that too. The other Gentleman had a point with the ejector spring being too tough also.

riverwalker76
April 4, 2010, 12:25 AM
What does the ejector spring have to do with loading?

It doesn't have any problems ejecting! It's loading that I'm having trouble with.

HiBC
April 4, 2010, 01:31 AM
I don't think an ejector spring would be the problem,but brass scrapings from hot loads can wedge up the ejector.That can prevent the case from seating into the bolt face,and therefore it is not centered up .I just see that watching cartoons in my head of the gun running.I may be wrong.
Taking a bbl extension off is ill advised.My understanding is they are torqued to 150 ft lbs and loctited.Re-assembly is not about torque,the bbl extension must be indexed to the gas port.

The case dia at the head is 376,so the chamber might be a couple thousandths bigger.Maybe if you got some fine 1/2 in dia mounted grinding stones with1/8 in shanks,maybe a round one,like a cherry,and a cone one like a pine tree,then you might have to dress one with a piece of carborundum to be about 120 deg,like a drill point.Get a tool called a pin chuck or pin vise.General makes a cheap set.No motors,no electricity.Using just your fingers and light pressure,what you will do is a bit like cutting a 3 angle valve job seat.Ink it with magic Marker to see progress.Start with the cherry.Spin it till to get maybe a ten thouandths corner break.Then ink it again,and just get maybe a 5 thousandths break with the other two stones.
Do not touch the chamber walls,work only on the edge.!/2 in tools should not enter.I would not consider a Dremel or drill.
Then you might sharpen a 1/2 in hardwood dowel to a90 degree include point,and put some 600 or 900 grit lapping compound on it,and spin that between your fingers a bit for a little polish.
Now,realize,I have not done this to an AR.I made the whole thing up.But it is what I might try.Then,of course,do a serious immaculate job of flushing,blowing all trace of grit out,then put a rust preventive in the chamber,bore area.I have seen barrel steel rust in minutes after a degrease with solvents.
Certainly,check out other options first,and get a second opinion from a gunsmith or someone AR knowledgable.This is not the first thing I would do.It bothers me the gouge is so far forward.Looks more like the rear end of the round is not coming up

Gunplummer
April 4, 2010, 07:36 AM
Exactly. If the ejector spring or extractor spring is too stiff , or jammed as you said, it will force the round in at an odd angle. It probably is a burr on the edge of the chamber.

1911rocks
April 4, 2010, 09:15 AM
Just an opinion. I'm sure you paid a healthy price for your new AR. When a retail price is calculated a cost model is developed. This model makes sure that the company doesn't lose money in case they missed something. In that cost model any Tooling, R&D, Marketing, Carrying Cost, back office costs and WARRANTY is "rolled up". The old model for firearms use to be that 1.5-3% of the cost was to cover warranty, larger percentage for "lifetime" warranty. So, if this was a new RRA AR, even a budget model, you've paid ~$30.00 for that warranty. Have you spent more than $30.00 of your time trying to resolve this? The other thing that happens with most Firearms Manufacturers (CZ, HK, SIG, Ruger) they use this Warranty Data as feedback for their DMAIC process (Six Sigma Process Improvement). This is used to improve manufacturing process and mistake proofing the process. In another way, if they don't know, how can they fix it? I'm a capitalist no apologies...even to those in D.C.

riverwalker76
April 4, 2010, 09:56 AM
Just an opinion. I'm sure you paid a healthy price for your new AR. When a retail price is calculated a cost model is developed. This model makes sure that the company doesn't lose money in case they missed something. In that cost model any Tooling, R&D, Marketing, Carrying Cost, back office costs and WARRANTY is "rolled up". The old model for firearms use to be that 1.5-3% of the cost was to cover warranty, larger percentage for "lifetime" warranty. So, if this was a new RRA AR, even a budget model, you've paid ~$30.00 for that warranty. Have you spent more than $30.00 of your time trying to resolve this? The other thing that happens with most Firearms Manufacturers (CZ, HK, SIG, Ruger) they use this Warranty Data as feedback for their DMAIC process (Six Sigma Process Improvement). This is used to improve manufacturing process and mistake proofing the process. In another way, if they don't know, how can they fix it? I'm a capitalist no apologies...even to those in D.C.

Off topic, but I will answer.

I built this rifle for half of the price of a new one in big name models. ;)

riverwalker76
April 4, 2010, 02:03 PM
Talked to an old friend this morning and he reminded me of a procedure we would do in the Corps if we needed to clean our bolt carrier group in a pinch. We would soak our BCG in automatic transmission fluid for a couple of hours, wipe them off, and shoot after that. It always kept them clean and running for a good 600 rounds before it needed to be cleaned again. I'm gonna try that and see if it helps.

The mag feed doesn't seem to be a problem. I tightened the mag catch an additional turn this morning to get it good and tight. No play now! I'll keep you all posted.

1911rocks
April 4, 2010, 03:43 PM
I read "new" and falsely assumed that it was a retail assembled weapon. Did you assemble the upper from a stripped upper or did you buy a complete upper?

riverwalker76
April 4, 2010, 04:40 PM
I bought a complete upper, but I have a new development.

I think I need to cut ramps in the upper receiver to get it to feed properly.

Please refer to the pic in my previous post that has a picture of the receiver. Can you see where the brass is hitting? If there were a feed ramp extended into the upper receiver would it be fixed?

Here is a pic of what it does to my bullets. The bullet is situated so that the right side in the pic is where the bottom of the bullet would be in the chamber. Observe what it does. It bends my bullets! Probably due to the drag on the lower. That's why I'm having feeding problems is because the BCG is petering out and using all of the energy on charging the round.

http://i363.photobucket.com/albums/oo78/AntlerandStone/DSC01150.jpg

HiBC
April 4, 2010, 06:23 PM
I do not know the topic extremely well,but there is an M-4 ramp,and there is the standard AR ramp.The M-4 ramp is cut a bit deeper and the bbl extension cuts should blend with it.I cannot tell if you have a problem.If it is incorrect,contact whoever built your upper.IMO,charging in with a dremel is usually ill advised.That black anodize is a wear resistant hard coat.The aluminum under it is pretty soft.
An engine builder might "massage" a piston.Breaking all sharp edges,etc.This sort of fine hand work can be done by a man building his own rifle.It is not likely in production.You do not have access with an assembled upper reciever,If you had only a bbl and bbl extension,you could lightly break all sharp corners,draw stone and lightly polish the ramps,etc,and that would be sweet.I also think 99.9% of the production of AR type rifles have not had this done,and they work.
Another grim possibility,you say you saved a lot of money gathering parts and assembling this rifle.Cool,I assemble mine,too,but I cannot say I save money as I buy what I consider quality over cost.It may be possible that a bargain reciever is not quite Mil-Spec.(And maybe you have top quality stuff so it isn't the problem)
Of course,the bent round would impede bolt closing and feeding.

Double Naught Spy
May 30, 2010, 07:28 AM
We would soak our BCG in automatic transmission fluid for a couple of hours, wipe them off, and shoot after that. It always kept them clean and running for a good 600 rounds before it needed to be cleaned again. I'm gonna try that and see if it helps.

So the automatic transmission fluid didn't work here either?

ScottRiqui
May 30, 2010, 08:50 AM
It appears that you have a non-M4 upper (no ramps cut into the receiver) and a non-M4 barrel (the ramps in the barrel extension come just barely out to the edge of the barrel extension, but the circumference of the extension is still an unbroken circle.) As such, the combination should work together, but if you're having feeding problems, you could cut shallow ramps in the receiver to "blend" the transition from receiver to barrel extension.