Ruger SR 556 - Carrier Tilt or normal wear?

B

buzzkillin

Inactive
Hi all
I know this is a topic that has been beaten nearly to death, but I'm trying to determine if the wear I am seeing after about 600 rounds is a carrier tilt issue, or just normal wear, so I'd appreciate some input.

What concerns me is not the wearing off of the finish, but the fact that there now seems to be a ridge in the buffer tube directly behind the buffer sprint pin that remains raised, compared to the rest of the lower buffer tube, which seems worn down. I hope the pics describes it better:

P1010115.JPG


P1010113.JPG
 
So, Flight, you think that the little ledge that has developed behind the buffer pin is normal? Looks like the tube has really been worn down pretty far. Maybe I'll take a sharpie and paint it in and see how quickly it rubs off.
 
Carrier tilt. Definitely; you don't see that kind of wear in a DI AR. Ruger enlarged the back end of the bolt carrier to avoid that, but there's just no way to eliminate it entirely. 600 rounds is also kinda early for that kind of wear- you might want to send those pics to Ruger to see what they think about it.

Still, I'm not sure that it's that worrisome. If the wear gets too bad, just replace the receiver extension. They're $30, and on a piston AR, they should probably be viewed as consumable.
 
It is a gas piston pushing a round bolt carrier in an upper receiver with no frame rails - the carrier is going to tilt and that is just a fact of life. The wear you are seeing is a result of that tilt.

The only question is whether that is unusual wear or wear that signals an impending function problem. It doesn't look like that to me; but I am not very familiar with the Ruger SR556. A normal DI AR has a lip that extends from the lower edge of the buffer tube and holds the buffer retaining pin in place. I don't recall off the top of my head if it has that tiny ledge in it or not as that question doesn't come up with DI ARs; but I'll take a look when I get a chance.

Is this a plinker that you can afford to shoot and watch for awhile or is this your home defense rifle or a rifle you use for work? If it is the former, I would just keep shooting it, keep a good round count on it and continue to document the wear with pictures. If it turns out the wear is normal, you've got some valuable information to share with other shooters. If it breaks, I am sure Ruger will fix it under warranty.

If you don't have the luxury of experimenting like this because you depend on the rifle, then I'd send the pictures to Ruger and see what they say.
 
Good advise guys, thanks. At this point, because the AR platform is still relatively new to me, as is the rifle, I am not using it as my hd gun. My goto remains my AK until I know I can fully rely on this weapon, so I DO have the luxury of waiting and observing. I will most definitely be keeping a log, both of pictures to keep an eye on the progression, and round count.

For now, as long as the thinning of the buffer tube slows or stops, I am not too concerned, and as pointed out, I can always just replace the receiver extension. I'm fine with that, as long as the weapon is not doing something it's not supposed to be doing. Having unintended wear-points on a weapon can obviously have consequences other places in the rifle as well.

I have already submitted a support request to Ruger, with links to my photos, and I'll make sure to post their reply here so others can benefit.
 
I'm also not familiar with SR556. Did you field strip and clean the rifle before you took it out for the first time? Did you notice if the edge of the buffer tube had a 90deg. edge or did it have the ramped look as it does now?
 
I don't recall off the top of my head if it has that tiny ledge in it or not as that question doesn't come up with DI ARs; but I'll take a look when I get a chance.
Click to expand...

If you're referring to the raised portion behind the buffer retaining pin, the one in the pic is the result of wear from the bolt carrier; the carrier has a channel in it to clear the pin, and obviously there's nothing there to wear on the tube behind the pin. I don't think it would cause any function issues (you'd wear the tube down to replacement before you reached that point).

From my admittedly limited experience with the Ruger and things I've read, this is on the extreme end, especially on this design.

I know somebody has developed a buffer with a "nub" on it that engages the bolt carrier to prevent tilt. Disassembly requires popping both front and rear takedown pins, since it would prevent tilting the upper off the lower (unless you chop part of the carrier, I think some have done so but I'm not sure if I would).
 
If you're referring to the raised portion behind the buffer retaining pin, the one in the pic is the result of wear from the bolt carrier; the carrier has a channel in it to clear the pin, and obviously there's nothing there to wear on the tube behind the pin.
Click to expand...

Yes, it does look like there is no "ledge" behind the buffer retaining pin, which would seem to suggest that the ledge is the result of wear after 600 rounds. The Ruger has a fatter rear end on the bolt carrier that is supposed to mitigate excessive tilt. Looking at how the wear stops abruptly, I'd guess that the bolt carrier is still tilting down during the initial movement to the rear and then the fat end is straightening it out as it enters the buffer tube (but past the lip).
 
RT, I read this post. If you notice, on his rifle the lip of the buffer tube has been worn down like mine, but on his rifle there is also scratching that extends up into to bt. The wear on mine seems to stop right after the lip of the bt, which indicates to me that the bolt is straightening after it's gone up over the lip. I don't know, but I'm very curious to know what Ruger says at this point.
 
So, I got my response from Ruger. Sounds like it jibes with what I was planning on doing, which is to wait and see if the problem worsens, or evens out. The fact that the tube is not scratched further up makes me hopeful that the issue with lessen from now on, but we'll see.

Ruger's response:

Response:
1.Our patented two stage piston reduces the initial energy impulse to the carrier, which reduces the amount of tilting force during the carrier’s initial motion.
2.We have an enlarged rear diameter on the carrier, which reduces the amount of tilt.
3.We have removed a portion of the forward carrier rails, which re-directs tilting force away from the upper receiver to the buffer tube.
4.We have a radius on the rear of the bolt carrier which reduces the amount of wear on the buffer tube that might result from carrier tilt.

So, our design has less carrier tilt, has less force behind the tilt, does less damage when it does tilt, and what little force/tilt is left is directed to an inexpensive buffer tube instead of an expensive upper receiver.

Wear in the buffer tube, as a result of carrier tilt, will most likely be present to some degree in nearly all rifles. Once the wear pattern is established, it is unlikely to worsen over the life of the rifle. In the unlikely event the buffer tube continually degrades over time, the rifle should be sent back to us for review. Degradation in the buffer tube can be a concern if the top of the buffer retainer plunger (the small pin that holds the buffer in the tube) and/or the bottom of the relief groove of the carrier (which allows the carrier to travel over the buffer retainer plunger) starts to get wear.
 
That's the nature of the beast with that piston design, but I wouldn't worry about it until it started getting into the receiver, then just replace the buffer tube.
 
Sam problem

i had such bad carrier tilt it wore the tube down to failure and the pin flew out so i sent it to ruger and they said they are going to replace the whole gun it should be there now but iam on my ship and wont be home till june we will se haow the new rifle works.
 
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