What is the Carrier Tilt?  Is that something that should concern me before I go with a certain system.  I have never heard of that.  I don't run my equipment hard.  Basically a range shooter.

It happens when the back of the bolt carrier tilts slightly downward when the carrier is traveling into the stock extension (buffer tube). It causes some wear on the bottom of the tube. There is a ton of pictures on this sight showing carrier tilt.

It can happen from the force of the piston pushing on the carrier causing it to tilt into the tube just like it sounds.   Each Piston MFG approaches it differently Adam Arms put "ski's" on the bottom of their carrier,  Osprey also has a fatter carrier and their carrier gas key has an opening so the tappet hits the same spot every time.   I have not noticed any issues but then again I only shoot a couple thousand rounds a year.  It really is an overblown issue.

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Ruger has a video on how they address carrier tilt:

http://www.ruger.com/products/sr556/extras.html

there is a FAQ video on this.

I see NO signs of carrier tilt on my Ruger SR556 and that is with 2400 rounds on it now.

If it was two years ago, I'd probably worry about tilt.  A lot of the older designs I've gotten my hands on have all shown some sort of tube wear.  Like one of the previous posts noted, all of the companies that are still in the piston game have updated their designs to reduce tilt and eliminate buffer tube wear.  If you're really paranoid, you can pick up a anti-cant buffer which prevents tilt from occurring.

Here's the link to the buffers:
http://www.heavybuffers.com/anticant.html

I have maintained all along that this is essentially a non-issue. A little finish worn off does not constitute a need to panic.

A recent thread here dealt with a shooter's new SR556 that had sustained considerable damage to the bottom edge of the tube due to "tilt" after just a few hundred rounds. It was determined (by me, ) that the contributing cause was a buffer tube that was one-turn short of being fully installed. This allowed the back of the carrier to slam into the edge of the tube instead of just bump the top inside surface, thereby causing quick wear and a popped buffer retainer. Had the tube been fully installed, no failure would have occurred.

Please, folks, this is a minor cosmetic issue in a part of the gun not even normally seen. *Even if* this minor wear continued for thousands of rounds, it's a condition easily monitored by simply opening the gun and pushing the buffer back a bit. If it ever looks like it's going to cause a problem after thousands of rounds, it's easily fixed by replacing the tube.

Tilt is an issue that has captured the hearts and minds of the piston haters.

That's for the paranoid who can afford that kind of money. But, I'm sure some will buy it to avoid a little shiny spot on the inside of their tube.

How many new tubes can you buy for $125.00?

Here are the results of the carrier tilt I'm seeing in my build.
Shavings:
http://i191.photobucket.com/albums/z295/_russ/guns%20n%20stuff/P1000606.jpg

Wear:
http://i191.photobucket.com/albums/z295/_russ/guns%20n%20stuff/P1000607.jpg

Aluminum all over the BC:
http://i191.photobucket.com/albums/z295/_russ/guns%20n%20stuff/P1000611.jpg

You dont get that with Osprey 416

What gp system are you using?

CMMG complete M4LEP2 upper.

Can you post another picture like the middle one––but with better light on the damaged part? Can you do the same thing with the pic of the bottom of the carrier? I know it's a lot of trouble, but I'm really interested in this issue.

Is the bottom of the carrier beveled?  Why?

I will try to get some better pictures.  The carrier is as it came from the factory, you would have to ask CMMG why.

If you look at the bottom of the carrier in the photo it looks like the shavings are coming from the lip on the back of the carrier when it is moving fwd in the tube. You can see at teh edge of the lip there is a line where the aluminum that has galled on the tube is sticking to the edge of the lip on the carrier. At least that is what it looks like from the pictures.

Carrier tilt is real. It is a matter of physics; every action has an opposite and equal reaction. When the op-rod of any piston system impinges upon the carrier lug it does so off axis causing the carrier to be thrust upwards into the upper receiver at the forward end and thrust downward at the carrier’s rear causing the carrier to collide with the buffer tube. These forces transferred directly into the upper receiver and buffer tube resulting in accelerated wear as noted most prominently within the buffer tube. Yes the amount of wear will vary from system to system. The reality is that every piston operated AR-15 or AR-10 type rifle will have this condition where the forces created by the carrier being actuated off axis by the op-rod will transfer directly into the upper receiver and buffer tube. This condition is not an issue with the direct impingement AR rifles because the bolt is essentially a piston that is centered within the carrier and when the discharge gases actuate the bolt and carrier it does so on axis driving the carrier directly rearward, essentially free floating. Now if one can accept that carrier tilt does exist, what to do about it? I think it is obvious that the industry believes it exists. The industry has devised numerous options for addressing carrier tilt all of which falls short of stopping the hardened alloy carrier from contacting the aluminum buffer tube and the resulting wear. Here is what I believe to be the best option. A bolt carrier that has an anti wear buffer integrated into the carrier to eliminate contact between the carrier and buffer tube. This carrier buffer also serves as an alignment tool to guide the carrier within the buffer tube as a tubular rail type system. It should be noted that every successful piston operated small arm that I am aware of has some sort of rail system to guide and offset the forces created by the physics associated with piston operated firearms. Additional benefits to be derived from a bolt carrier buffer assembly. 1) Prevents carrier from tilting, thus allowing a larger surface area of the carrier to make contact with the upper receiver reducing upper wear. 2) By supporting the carrier at the rear throughout its entire range of travel better aligns the bolt with the barrel extension. 3) The polymer type buffer material also acts as a buffer between the bolt carrier and buffer. In addition the carrier buffer absorbs recoil shock and quiets the rifles action. Note the industry standard seems to be cutting the rear of the carrier at angle, resulting with two undesirable conditions. 1) An unsupported carrier at the rear allows even more carrier tilt at the forward end resulting with an even greater force being transferred directly to the upper receiver. 2)  The angled cutting of the carrier causes the carrier to jump in a ramp like fashion colliding with the buffer tube farther down on the top side of the buffer tube, out of sight out of mind. The idea of a buffer with a lug that enters the rear of the carrier would help offset carrier tilt, but it merely transfers the wear from the carrier and buffer tube to the buffer and buffer tube. Furthermore, I have some reservations about the buffer tilting and interfering with the proper operation of the buffer spring, potentially causing a malfunction. In addition a buffer type device requires both take down pins to be removed before allowing access to the bolt, bolt carrier, upper, or lower receiver.
http://i969.photobucket.com/albums/ae180/FallenHops/CarrierBuffer1copy.jpghttp://i969.photobucket.com/albums/ae180/FallenHops/CarrierBuffer2copy.jpghttp://i969.photobucket.com/albums/ae180/FallenHops/CarrierBuffer3copy.jpghttp://i969.photobucket.com/albums/ae180/FallenHops/CarrierBuffer4copy.jpghttp://i969.photobucket.com/albums/ae180/FallenHops/CarrierBuffer5copy.jpg

Interesting that the majority of all tilt issues are from Ruger owners. I have never seen it present itself in a LMT, Hk or LWRCI FWIW... Those companies also addressed it before hand with an upgraded BCG like this....>

What does Rugers BCG look like?

Carrier Tilt on the extension tube is not a big deal, you should remove the metal with a file, open up the mouth of the stock tube.

The larger issue with carrier tilt is not really there because that won't do anything but mess up your stock tube, but if you look at where the bolt group is sitting when the round is chambered you will see the anodizing start to disappear near the bottom, when this breaks through the anodizing it could be a problem.  Even with this I have seen them run after screwing up the the anodizing for a heck of a long time, it is still going.

Says who?

Also, it is not true that Ruger has not addressed tilt. Follow this link and click on the video regarding carrier tilt.

http://www.ruger.com/resources/videos.html#

Too Bad Kurt (kkf) was not still alive I was talking to him and he working on the true solution to this issue and none of systems out there would have even compared i was waiting on it,  thats why i waited so long before going piston


no i'm not sharing the idea .....yet

Here's a better shot of the buffer tube wear.
http://i191.photobucket.com/albums/z295/_russ/guns%20n%20stuff/P1000633.jpg
Back of the upper receiver.






http://i191.photobucket.com/albums/z295/_russ/guns%20n%20stuff/P1000626.jpg
Cam pin wear inside the upper receiver.
http://i191.photobucket.com/albums/z295/_russ/guns%20n%20stuff/P1000621.jpg
And here is what I hope will fix it, I made this in a few hours after work last week (no plans to make more or sell any, just couldn't justify spending $100 for something I could make myself).  Well, this and the POF roller cam pin I ordered.
http://i191.photobucket.com/albums/z295/_russ/guns%20n%20stuff/P1000639.jpg



 

All of the short stroke piston systems will do this no matter who makes it.  You may see it vary on a gun by gun basis.  In high speed you should see the bolt group and the barrel deflection.  

There was once the perfect piston solution that was made on a weapon created for the SAW trials.  It apparently dominated the M249 but was kicked out, The gun I think was named the Rodman gun and it had 2 pistons, one above and one below the barrel.  Little barrel deflection during operation, a little closer to the actual AR.

See my post above. This anti wear carrier buffer system with thousands of rounds fired in full auto, suppressed, and semi-auto has eliminated the excessive wear associated with piston operated ARs. Here is a link of just one day of testing that has been performed with the anti wear carrier buffer: Testing The Anti Wear Carrier Buffer This test is continuous auto fire, 90 rounds suppressed, a total of 930 rounds, 500 rounds silver bear and 430 PMC. I am also using this carrier buffer in the .308 piston system with the same results. The wear in the .308 ARs without this carrier buffer is much worse than the 5.56 because the added weight and length of the AR-10 carrier magnifies the effects of the physics that cause carrier tilt. After more then two years of testing various carrier configurations including the anti tilt buffer idea nothing has matched the performance of the anti wear carrier buffer. Here are my findings on the anti tilt buffer. The idea of a buffer with a lug that enters the rear of the carrier does help offset carrier tilt, but it merely transfers the wear from the carrier and buffer tube to the buffer and buffer tube. Furthermore, I have some reservations about the buffer tilting and interfering with the proper operation of the buffer spring, potentially causing a malfunction. In addition a buffer type device requires both take down pins to be removed before allowing access to the bolt, bolt carrier, upper, or lower receiver.  If you are interested in my full discussion  on how I believe the carrier wear issues can be eliminated read these post at the following links:
http://www.ar15.com/forums/topic.html?b=3&f=126&t=495676

http://www.ar15.com/forums/topic.html?b=3&f=126&t=495344

http://www.ar15.com/forums/topic.html?b=3&f=126&t=496060&page=1

When you pull your charging handle, the force is applied to the same part of the carrier as the piston operating rod. When I racked my AR a few times with the CMMG carrier, I noticed rubbing on the bottom of the CMMG 1 piece bolt carrier.

So how can I get one of these Carrier Buffer? I haven't been able to find  a web site for Black Rifle Arms.

Has anybody speculated that the carrier tilt damage might be exacerbated by the use of the Accu-Wedge?  The wedge works by putting a little upward pressure on the bottom of the upper.  This would increase the distance that the carrier has to "tilt" to get into the buffer tube.

Or not....

Carrier tilt on my SR556, less than 500 rounds...

Ruger's response? 'It's a limited carrier tilt gun."

http://www.wettworks.com/imgs/ct1.jpg
http://www.wettworks.com/imgs/ct2.jpg
http://www.wettworks.com/imgs/ct3.jpg

The Problem with carrier tilt is that the more the wear to the buffer tube the more the carrier wants to till as the metal in the buffer tube that use to try and hold the BCG up is now worn away. Hence an even more pronounced "tilt" will ocure. Now you have to think about this for a second.  The BCG is tilting right....whats on the other end of that BCG?  Correct, the bolt itself. What is that bolt now trying to do? Correct again... it;s digging into the barrel lugs.

The point to all this is if you have a piston gun with carrier tilt wear i think you should try one of the fixes around that slows or stops it.

On a serious note I would be pretty pissed, and do not think that is something you should just have to live with.  It sucks to buy a new product and then have to try to find a fix for it unacceptable.

Baloney. Your first point might have some validity if the fit and alignment of the carrier into the receiver extension (buffer tube) was required to be precise. It's not. Take out the buffer and spring and see how much clearance there is when you insert the rear of the carrier into the tube. Also, bazillions of AR users have been running guns with sloppy upper to lower fitment for years without any of the bolt issues you worry about. The amount of wear people are seeing is miniscule. It's going to turn out, IMO, that for the vast majority of users CT will be self limiting and cause zero, zero, functionality issues.

I own 2 piston guns and 1 DI version.. I don't have a dog in this race.. What I described above that you commented on is simple physics.. You can deny that.. Call it Baloney all you want.. The fact remains.. If the rear of the BCG is tilting down so the front must tilt up.. Simple as that.. There is no dabate. Now whether or not this matter at all is a thread of another day..

The bolt is not a rigid part of the bolt carrier and will take up some amount of misalignment.


0.020" of carrier tilt, front to back, would give you about 0.001" lug engagement difference, but when this occurs, the force on the bolt from the case has dropped very low because the chamber pressure has dropped to basically zero (relatively) by the time extraction occurs.





So the point is moot...
 

And you measured this?  How?  You throw numbers around like you actually took up a caliper and studied this.  So yes, I agree... Your opinion is moot

Yes actually, i did, when i was designing the bufferless pistol in my avatar.  Since my carrier was shorter, it was less stable, and therefore i went with a modified/extended DI system instead of a short stroke piston, because it would have chewed up the upper from carrier tilt. The oversized gas key also acts as the action rod and retains the action spring, while adding stability to the carrier.





And I'd say an ME degree qualifies me to at least know how to use calipers and micrometers...  





(Also nice way to paraphrase in your quote and leave out the important stuff...)
 

If i had a ruger doing that... i'd have to at least toss on the POF tube set... anti tilt buffer, etc.

Looks like they took the same route as the Japanese did with the gas piston design.

Type 89 rifle also use the dual diameter gas piston.

I understand the physics of your hypothesis very well, thank you. As already pointed out, the bolt is not a rigid part of the carrier (obviously), and there is a small but observable amount of "wiggle room" in the fit of the bolt in the carrier. There has to be to allow for manufacturing variance. Likewise, there are tolerances for the fit of the bolt lugs into the barrel extension. The *typical* amount of tilt wear I've seen in pictures here and elsewhere hardly amounts to more than wearing the finish away. Yes, there have been reports of more extreme wear, but they have been very rare. If someone's gun is showing that kind of extreme wear and it appears to be getting worse, I would totally agree that some remedial measures need to be taken.

In the meantime, panic at the first sight of finish wear is a total overreaction. Shoot the gun. Monitor the wear, and relax.

Where are the verified cases of broken parts or malfs due to CT?

I can tell you that I worry about carrier tilt because I use a MP M93 BS and when that tube is done I'm fucked for that BS.  I don't mind wear, but not at the expense of a $200 plus BS.

What is the POF tube set designed to do?

I compared my DI AR15 to the piston carbine AR15 and noticed that with the piston, the POF roller cam dug into my upper receiver. When you invert the rifle, pop open the ejection cover and remove the CH and BCG, you can see a lot of the anodizing removed from the upper channel that is visible via the port.



On the DI, that channel looks silver. On the piston AR15, the channel is also silver but there's a noticeable "dent" from the POF roller cam digging into the metal. I never shot my CMMG piston kit using the standard cam pin, I only used the POF roller cam because the ARFCOM hive mind all recommended the roller cam as being superior.



Now, looking at the CMMG piston kit design - there's nothing to support/direct the operating rod straight back. It could tilt to the side a little. Looking at the Adams Arms kit, the bushing in the upper receiver acts as a final support/guide for the operating rod to ensure it only goes straight back.



As for carrier tilt, funny thing is that on my DI AR15 (24" HBAR, rifle length gas system) there is some buffer tube wear on the sides (DPMS commercial 6-position M4 stock) but not much.

Basically, the "bottom" of the buffer tube extends past the buffer retainer detent, so that that the bolt carrier is always "riding" in the buffer tube. It doesn't change whether or not your carrier tilts, but it stops the lower edge of the carrier from striking the beginning of the buffer tube during tilt.