Hey guys,
First of all, Happy Veteran’s Day to all the vets on here.
Here is a pic of my buffer tube/retaining pin. The tube has caught the retaining pin, but is it good enough?
I already torqued and staked the castle nut, but . . .
Edit: I added some better pictures across all three current builds. You should be able to better see which one I am concerned with. Also, the lowers are Aero and the tubes are all Larue.
It is barely contacting the buffer detent. I would not trust it. The buffer tube is usually almost all the way up to the base of the tip of the detent. Yours is barely on the detent itself.
That’s extremely minimal engagement. Can you turn the buffer tube another full rotation, or does it hit the tip of the detent first? If you can get another rotation, I’d do it. If not…I’m not really sure what your options are other than to try a different tube.
Naw, I can’t turn it another full rotation. I thought everything looked good before I staked it too. I need a light on my workbench.
Is it normal for buffer tubes to not take to certain receivers? My other tubes and receivers (from the same respective manufacturers) mated up nice and tight.
It looks like the tube is jammed up against the retaining pin, instead of the pin being under the tube. It probably would have been fine if you would have held the pin down enough when screwing the tube in.
I’ll double check, but I am pretty sure it is under the tube.
This is exactly what I thought.
I checked, the retainer is under the tube -just a bit.
You should be able to get another full turn on the RE. Be sure to push down on the retainer when you do. Unfortunately, you’ll need to break the staking which isn’t hard, but your end plate will be left kinda ugly. Either replace the end plate or use some cold blue or paint, or don’t.
You really don’t want the retainer to pop out during firing.
It happens from time to time. My buddy absolutely could not get his receiver to work with a LaRue buffer tube. I checked it for him and it was just perfectly (imperfectly?) between rotations. One rotation out wouldn’t engage, one rotation in would hit the pin. I don’t think it’s very common but it can happen based on the thread pitch vs. the dimension between the edge of the retaining pin and the post. Really annoying but at least buffer tubes don’t cost too much money.
The tube appears under the pin to me.
Does the pin push down freely to release the buffer? It must be an illusion on that picture because it doesn’t look like the pin is under the tube. I’ve had some tubes that just barely catch the edge of the retaining pin. As long as the retaining pin is under the tube, even barely, it should be fine. The buffer should never touch the pin after you close the receivers.
For those saying it looks likes the pin is under the tube…look at the 1:00 position. The tube has a little bit that’s offset and overlaps the pin. It barely overlaps it, but it’s there.
I see that and the rest of the pin looks like it’s on top of the tube, that’s why I asked if the pin pushes down freely.
It’s the M.C. Escher of buffer tubes. 
Yeah the pin pushes down freely, only resistance is the spring. I doubled checked, and it is under the tube.
It is odd because my other lowers all use Aero receivers and Larue tubes, but this is the only tube that doesn’t overlap the retainer quite a bit -nearly butts up to the little “pin” on top of the retainer. I will take another photo for a point of comparison in the morning.
Literally trying to get the buffer tube perfectly aligned was the most challenging parts of the build so far -not the bolt catch haha. Tubes wanted to rotate when torquing the castle nut.
Just don’t know if I trust it as is…
I wouldn’t trust it as is. That looks like it’ll pop up under recoil.
Yeah, Larue products seem to have their own quirks in my experience.
I will try and back off the nut without ruining the qd plate. Otherwise I’ll just order another from Earl over at Impact Weapon Compenents. I’ll let you guys know how it goes.
Yeh that can be tough. Most of the time I have to do it a couple of times before I get a torqued castle nut on a straight, indexed tube. This can be a PITA when you have OCD. I would like to see another picture of yours, it doesn’t look right.
You really don’t have to trust it, unless you want to. The rifle/carbine will function just fine without the retainer. Just have to hold the buffer back with your finger until you get the upper partially closed.
I wouldn’t shoot it with the retainer barely held in place like that, you do not want it popping loose and risk getting the spring and the retainer in your action while firing.
So you either need to fix it or remove it.
I noticed your receiver extension has a partial lip on it, like these do, you can see it in your picture:
What I would do is disassemble, and then reassemble w/o the retainer, stop at the edge of the ‘hole’ and then rotate one more turn, see if filing off that lip would give you a proper fit. I ass-u-me that is what the lip is for.
Or, you could by an offset retainer pin from this guy: http://commonbullets.com/wp/archives/1727
Good luck. whatever you decide.
ETA: your buffer tube/receiver extension shouldn’t be turning much at all, their is a machined groove at the bottom of the tube/extension which corresponds with the tang on the end plate to stop rotation.
