Extraction Question???

[Mac5.56]

Is a ripped rim on a case usually an indicator of a weapon issue, or an ammo issue?

Ammo: 5.56 Romanian Surplus
Weapon: MP15, with black o-ring on extractor, 5.56 chamber, carbine buffer, and being ran pretty dry, but not bone dry. After the case was removed with a cleaning rod there was very little carbon (if any) buildup on the casing.

After failure I ejected magazine, inspected the extractor and saw brass shavings, looked at case and saw torn lip. Re-chambered bolt and attempted a manual extraction, with no luck.

So, Ammo, or Weapon?

[Robb Jensen]

Probably a little of both.

If that gun were in front of me I'd check its chamber with a 5.56mm NATO neck and throat checker and if it failed I'd ream it to a true 5.56mm NATO using the 5.56mm NATO neck and throat reamer (both are available from Ned Christiansen of http://www.m-guns.com/).

I'd also switch from a CAR buffer to either a H or H2 buffer. H should always be the lightest buffer used in a CAR gas length AR.

[CAPT KIRK]

I have heard that the Romainian brass is soft..... I have always advocated, practiced and never regretted the habit of spending a little more for good ammo.

I also agree with GOTM4 on the buffer suggestion if you are running a carbine length gas system, I tend to like the H1 buffer/FA bolt carrier combo (which is what John Noveske puts in all his guns).

[Mac5.56]

The gun had an extraction failure a year ago on a Wolf shell, and after much talk on this forum I returned it to SW with the request that they make sure the chamber was a 5.56. The work receipt indicated that they had reamed the chamber. I may look into having it checked here locally though.

So, having a heavier buffer will help this as well? I never completely understood buffers. The heavier buffer slows the action down right? So that means that the extractor will be hitting the round with less force I'm assuming?

[Robb Jensen]

The gun had an extraction failure a year ago on a Wolf shell, and after much talk on this forum I returned it to SW with the request that they make sure the chamber was a 5.56. The work receipt indicated that they had reamed the chamber. I may look into having it checked here locally though.

So, having a heavier buffer will help this as well? I never completely understood buffers. The heavier buffer slows the action down right? So that means that the extractor will be hitting the round with less force I'm assuming?

Many times on commercial 16" CAR length gas barrels the system is overgassed (which is due to a larger than the mil-spec gas port of .062"). CAR length gas guns have a shorter system and almost double the gas port pressure of the ARs original size (20" barrel with rifle length gas system). One of the bad effects of this shorter higher pressure system is that it causes the bolt carrier to begin to move rearward and trying to unlock the bolt while the pressure is still very high in the chamber and barrel and while this fired shell casing is still stuck up against the chamber walls in full expansion. A compounding problem can be 5.56mm NATO pressure ammo in a chamber which is a little tighter than 5.56mm NATO, it can be so bad that it'll pop primers lose on the empty casings. This is why midlength, intermediate length and rifle length gas systems feel softer because they unlock a little later and the bolt velocity is slower and there is a lot less gas pressure going through the system.

The heavier buffer will delay the bolts movement a little and allow the chamber pressure to drop a little bit more. A H buffer should be the absolute lightest buffer in a CAR length gas gun. This is what comes in new Colt carbines (like the 6920, 6721, 6520 for example). You can go heavier usually without any ill effect unless you're running some really weak ammo. The Spikes T2 buffer is pretty nice as is the H2 buffer. I'm experimenting with a Spikes T2 right now.

Extractors pull, ejectors push. The extractor pull the casings out of the chamber. Once the casing has cleared the barrel extension and upper receiver the ejector pushes the casing off of the bolt while the bolt is traveling rearward.

Also, the front half of your bolt carrier should be almost dripping of oil when you're actually shooting it.

[MarkG]

Probably a little of both.

If that gun were in front of me I'd check its chamber with a 5.56mm NATO neck and throat checker and if it failed I'd ream it to a true 5.56mm NATO using the 5.56mm NATO neck and throat reamer (both are available from Ned Christiansen of http://www.m-guns.com/).

I'd also switch from a CAR buffer to either a H or H2 buffer. H should always be the lightest buffer used in a CAR gas length AR.

If your barrel and chamber are chrome lined, how can it be reamed?

[thopkins22]

If your barrel and chamber are chrome lined, how can it be reamed?

Because you use the one gotm4 linked to which is harder than the chrome.

[Iraqgunz]

I would try and H buffer and I would probably remove the O-ring just to see what happens.

[Mac5.56]

I think I get it, but why remove the O-Ring? Are you thinking the extractor is too much for the ammo?

[Iraqgunz]

I am just thinking out loud. You really don't need it on a proper functioning 16" carbine and though I wouldn't say your issue was caused by too tight of an extractor, there is such a thing as too much extractor tension.


I think I get it, but why remove the O-Ring? Are you thinking the extractor is too much for the ammo?

[Robb Jensen]

If your barrel and chamber are chrome lined, how can it be reamed?

By hand in about 1-2 min. I done in excess of 400 barrels with my reamer from Ned Christiansen. Are you familiar with the reamer? I ask because I get this question everytime I bring up the reamer. Chrome lined, stainless, chrome moly doesn't matter. Removing that little bit of chrome in the neck and throat doesn't hurt anything.

A description of the reamer from Ned from his website:

Neck and Throat 5.56 Reamer

Now also available in 6.8 SPC with long freebore and throat! Add $20 for 6.8 SPC.

A common problem when firing 5.56 mil-spec ammo in an AR15 with a SAAMI-spec .223 chamber, is that once in a while a spent primer will fall out of a case as it is extracted. Sometimes the primers fall clear and there's no problem, other times they will go under the trigger and get wedged, rendereing the rifle inoperable. I've seen some extreme cases of this where the hammer and trigger were actually hard to get out. I've seen them get wedged between the charging handle and the inside of the receiver, with the bolt out of battery, so that the gun had to have the stock removed so the bolt could be removed to clear the primer. It is not unknown for the primer anvil get stuck on the tubular portion of the carrier key! Popped primers are due in part to the tighter, shorter freebore and shorter, more abrupt throat of the .223 chamber, causing a pressure spike with the hotter, mil- spec ammo. This reamer will address these areas as well as making sure the neck diameter is not too tight or short, without changing headspace. It does not cut the shoulder or anything behind it; it stops off on the shoulder. Of course, whatever rifle you're shooting, you could just look at what's stamped on the barrel-- it might say .223, or it might say 5.56, or it might say nothing. You could call the manufacturer and ask them what chamber you have, but even if you get to talk to somebody who understands the question, they likely don't really know. They may tell you what you want to hear, but truth is, not many AR15 manufacturers make their own barrels. They buy them from someone else, so they don't really, truly know what chamber you have. Some of them will flat decline to discuss it with you.

This reamer is designed as an easy, quick and sure way to know. You just open the upper receiver, remove the bolt group, drop in the reamer with some oil, and slowly turn it in (clockwise only, never reversing it), using a lot of turns and very little pressure. The handle centers itself in the upper receiver. When ithe reamer bottoms out on the chamber's shoulder it will spin freely-- it has stopped cutting and you are done. When you have done this, you know for sure you have a chamber with proper 5.56-plus dimensions in the critical freebore and throat area. Primer popping due to pressure spikes in a short leade will cease, but be advised there can be other factors in popped primers such as hot ammo, hot chambers, and improperly loaded ammo. The new version ($240, shown above) has a redesigned handle that is custom machined from aluminum barstock, so it is quite a bit lighter (handle and reamer weigh less than the original handle alone). It is also shorter to take up less room in your toolbox, and, most importantly, it functions as a storage case for your reamer. When you are finished reaming, simply remove the reamer, reverse it, and insert it into the handle-- your expensive tool is now very well protected and not taking up extra room in your toolbox. There is also a slot in the handle to accept the Allen wrench you need to turn the set screw that retains the reamer. The Allen wrench is retained in the handle so everything you need is right there.

What about chromed-lined chambers? The good news is that in my experience, Colt AR15 chromed barrels have a proper 5.56 chamber. I would consider most others to be suspect. The reamer has been subjected to a secondary heat-treating process, titanium carbo-nitride, which makes it capable of correcting under-spec chromed chambers. Obviously it will do fewer of them, but I have yet to hear of one of my reamers geting dull-- and my personal one has done at least a few dozen chromed chambers. Will removing the chrome be a problem? No. Plenty of AR's don't have chromed bores and chamber and they work fine. I've sectioned some chromed barrels and the chrome doesn't last that long in the throat area anyway. Removing chrome in the chamber won't cause the area to peel like bumper chrome.

[ST911]

By hand in about 1-2 min. I done in excess of 400 barrels with my reamer from Ned Christiansen. Are you familiar with the reamer? I ask because I get this question everytime I bring up the reamer. Chrome lined, stainless, chrome moly doesn't matter. Removing that little bit of chrome in the neck and throat doesn't hurt anything.

Agreed. Ned's reamer is a lifesaver, and a must-have.

[CAVDOC]

help me understand-because right now I do not- if you get chrome lining to retard chamber rusting and to prolong barrel life, if you remove the chrome from part of the barrel and chamber does that sort of negate the purpose in the first place?

[ST911]

help me understand-because right now I do not- if you get chrome lining to retard chamber rusting and to prolong barrel life, if you remove the chrome from part of the barrel and chamber does that sort of negate the purpose in the first place?

You're only cutting a very small section of the leade/throat, which will erode with time anyway. From Ned's description, emphasis mine:


What about chromed-lined chambers? The good news is that in my experience, Colt AR15 chromed barrels have a proper 5.56 chamber. I would consider most others to be suspect. The reamer has been subjected to a secondary heat-treating process, titanium carbo-nitride, which makes it capable of correcting under-spec chromed chambers. Obviously it will do fewer of them, but I have yet to hear of one of my reamers geting dull-- and my personal one has done at least a few dozen chromed chambers. Will removing the chrome be a problem? No. Plenty of AR's don't have chromed bores and chamber and they work fine. I've sectioned some chromed barrels and the chrome doesn't last that long in the throat area anyway. Removing chrome in the chamber won't cause the area to peel like bumper chrome.

I've borescoped barrels after reaming and periodically since, and not found any corrosion or undesirable effect. In my book, what minimal possibility there is of negative side effect is a small price to pay for having a known-good 5.56 chamber.

[MarkG]

You're only cutting a very small section of the leade/throat, which will erode with time anyway. From Ned's description, emphasis mine:

I've borescoped barrels after reaming and periodically since, and not found any corrosion or undesirable effect. In my book, what minimal possibility there is of negative side effect is a small price to pay for having a known-good 5.56 chamber.

There is no such animal as a 5.56, 5.56mm or 5.56mm NATO chamber, period. Just like 9mm NATO and 7.62 NATO, all are caliber designations. If you disagree, please let me know who can I call at NATO to get a copy of the print for the chamber? Given the fact that it is NATO, all countries using a 5.56mm projectile have the same chambers in their rifles right?

Reaming a hard chromed chamber is bad idea. If your chamber is out of spec, replace the barrel or buy a properly manufactured rifle from the start?

Did Ned get a copy of Colt's crown jewel of secrets to make his reamer? Where did his data come from. For his reamer to possibly work, you have to assume the rest of the chamber has been cut correctly. If it hasn't, you now have 5.56mm SHIT chamber.

:D

[ryan]

There is no such animal as a 5.56, 5.56mm or 5.56mm NATO chamber, period. Just like 9mm NATO and 7.62 NATO, all are caliber designations. If you disagree, please let me know who can I call at NATO to get a copy of the print for the chamber? Given the fact that it is NATO, all countries using a 5.56mm projectile have the same chambers in their rifles right?

Reaming a hard chromed chamber is bad idea. If your chamber is out of spec, replace the barrel or buy a properly manufactured rifle from the start?

Did Ned get a copy of Colt's crown jewel of secrets to make his reamer? Where did his data come from. For his reamer to possibly work, you have to assume the rest of the chamber has been cut correctly. If it hasn't, you now have 5.56mm SHIT chamber.

:D

Arent you the guy that called BCM chicom junk?

[Robb Jensen]

There is no such animal as a 5.56, 5.56mm or 5.56mm NATO chamber, period. Just like 9mm NATO and 7.62 NATO, all are caliber designations. If you disagree, please let me know who can I call at NATO to get a copy of the print for the chamber? Given the fact that it is NATO, all countries using a 5.56mm projectile have the same chambers in their rifles right?

Reaming a hard chromed chamber is bad idea. If your chamber is out of spec, replace the barrel or buy a properly manufactured rifle from the start?

Did Ned get a copy of Colt's crown jewel of secrets to make his reamer? Where did his data come from. For his reamer to possibly work, you have to assume the rest of the chamber has been cut correctly. If it hasn't, you now have 5.56mm SHIT chamber.

:D

You should contact Ned with your questions and suggestions instead of posting your ill informed questions/comments here.

His website is http://www.m-guns.com/

He's also a member here on M4C, notice the Industry Professional under his name?
https://www.m4carbine.net/member.php?u=528

[Iraqgunz]

Well I am not going to pretend like I am an expert, but you're wrong. It's very easy to say just replace the barrel. And in many cases that may be the case. However, if you are a large police dept. or a Private Military Company (as was my situation in Iraq) where we had 500 BM carbines, replacing the barrels isn't an option.

Unfortunately someone didn't so their homework and we needed a solution. Neds' reamer worked and we were able to get our stuff up and running.

I don't understand why he would need to contact Colt. It is very easy to get a Colt barrel and make a cast of the inside or cut the chamber area away and get the proper measurements and dimensions.


There is no such animal as a 5.56, 5.56mm or 5.56mm NATO chamber, period. Just like 9mm NATO and 7.62 NATO, all are caliber designations. If you disagree, please let me know who can I call at NATO to get a copy of the print for the chamber? Given the fact that it is NATO, all countries using a 5.56mm projectile have the same chambers in their rifles right?

Reaming a hard chromed chamber is bad idea. If your chamber is out of spec, replace the barrel or buy a properly manufactured rifle from the start?

Did Ned get a copy of Colt's crown jewel of secrets to make his reamer? Where did his data come from. For his reamer to possibly work, you have to assume the rest of the chamber has been cut correctly. If it hasn't, you now have 5.56mm SHIT chamber.

:D