Aside from the obvious issues currently surrounding this firearm in NJ, have any A4 owners had issues with the buffer receiver pin breaking? Mine sheared and the broken off tip ended up in the trigger group, locking up the trigger. Luckily, when I took it apart at home, I was able to recover the broken piece - it didn't have a clean break, it was worn heavily on one side before it snapped from being thinned out. Just got this in Sept of last year and have less than 500 rounds through it. Wondering if anyone else has had a similar issue.

Have 600 thru mine, just looked at that part, no noticeable wear.

Since you need one anyway..

https://www.tacticallink.com/forward-controls-design-reinforced-buffer-retaining-pin.html

 

What shape is the buffer in?

Here's some photos of what was going on...

-The edge of the pin facing away from the buffer is showing wear where the break happened (pic 1)
-On the channel in the bolt there are some marks from contact (red arrow) Figuring that this was from the top of the retainer pin contacting, although the broken off top of the pin doesn't seem to have any wear.  Where the bolt weight meets the end of the bolt, there is a lip (white arrow) from the two channels not lining up. (pic 2)

-The buffer isn't chewed up. What ever slight scrapes appear to be from it popping out when opening the upper (pic 3)


-The broken off tip of the pin showing impact wear below the top edge, I'm guessing from the misaligned bolt/weight (pic 4)

 

 

 

 

 

Could just be a random failure.  Those parts are wear parts and can eventually go... and if there's a flaw in the metallurgy it can go even faster.

We went through 1k rounds in a Troy A4 in an hour and had 0 issues... 

Take out the wedge. I have seen them cause soooooo many issues! They can create a step right were the bolt carrier transitions from the upper receiver to the receiver extension and create malfunctions and excessive wear.

Those things are completely unnecessary. Yes yes, I know - there will be unseemly play between the upper and lower. It will be OK. Promise.

Also, is that a 9mm carbine? Because they can really slam their bolt carrier around if they have the wrong action spring/buffer combo.

19 minutes ago, High Exposure said:

Take out the wedge. I have seen them cause soooooo many issues! They can create a step right were the bolt carrier transitions from the upper receiver to the receiver extension and create malfunctions and excessive wear.

Oh man I didn't even notice that - yep get rid of it.

is it possible that the bcg is over-traveling?

On 2/16/2023 at 7:07 PM, Redipski said:

Here's some photos of what was going on...

-The edge of the pin facing away from the buffer is showing wear where the break happened (pic 1)
-On the channel in the bolt there are some marks from contact (red arrow) Figuring that this was from the top of the retainer pin contacting, although the broken off top of the pin doesn't seem to have any wear.  Where the bolt weight meets the end of the bolt, there is a lip (white arrow) from the two channels not lining up. (pic 2)

-The buffer isn't chewed up. What ever slight scrapes appear to be from it popping out when opening the upper (pic 3)


-The broken off tip of the pin showing impact wear below the top edge, I'm guessing from the misaligned bolt/weight (pic 4)

 

 

 

 

 

I realize this is a year late, but I see the issue has been identified but the solution was not, so I'm posting for you or anyone else with the same issue.

 The cause was the buffer retainer coming up too high, it's supposed to live in that groove only contacting the face of the buffer not the bottom of the bolt. The *reason* it's coming up too high is the lower wasn't assembled correctly.

 When you look at the bottom 1/2 of the threaded end of your receiver extension (buffer tube) you'll notice a "ramp" on the end profile, that "ramp" section is supposed to go over the outer diameter of the buffer retainer enough to hold it down lower where it doesn't contact the bolt (or bolt carrier on non blowback models) To fix this, you need to loosen the castle nut (be careful with the takedown pin detent spring that lives behind the end plate) and thread the tube in another revolution until that "ramp" retains that pin by the tapered shoulder. That buffer retainer shouldn't be able to pop out and get lost in the field during a simple field strip and the way it's assembled it's entirely possible. After that's corrected you should ensure the end plate/castle nut are staked properly so it doesn't loosen and get sloppy.

hope this helps someone.

My 9mm Troy was the same way, the 5.56 Troy was not, odd but probably a different persons work bench at the factory I suppose.