Buffer tube and buffer stop Q

[RP1911]

I just installed a PSA buffer tube and buffer stop. There is barely any engagement of the stop. The buffer tube does not seem to have the correct accentuated lip to engage the stop properly.

Here's a pic. Let me know if I am correct and should I be sending the buffer tube back to PSA?

[jfifer]

There could be a burr holding it in, or the spring is too short

[Brandon04GT]

I basically ran into the same problem with a BCM tube on a JD Machine lower. How much of a gap do you have between the front of the stock and the castle nut when the stock is fully collapsed?

In my case, I was almost able to make another complete revolution of the buffer tube without any issues. All I had to do was notch the buffer tube SLIGHTLY for it to clear the buffer retainer. That's what I ended up doing.

[kcstott]

You have to remember that the threads on these two parts are not clocked or indexed to each other in any way.

From the US Army's TM on the M4. "screw the buffer tube into the receiver until it retains the buffer retainer. Align the lug or the receiver end plate into the rear of the lower receiver, screw the locking nut forward until it contacts the receiver end plate. tighten until snug torque to 40 in/lbs +/-2

[RP1911]

Brandon,

I actually did exactly that before you posted. One complete revolution and it now sits on the retainer well.
Thanks for the responses.


Kcstott,

I now have an additional issue. The safety indicator point is dropping just before the fire (bullet) pictogram. I can actuate the trigger from this position. If I rotate it more it will not stop.

I extended the pin spring to get a positive pressure but that is not solving the issue. I think the (80%) completed lower maybe off. I tried the selector on two other (80%) completed lowers from the same outfit and all three have the same issue.

BTW, it's not my first go around. I have built several.

[Jason25]

I now have an additional issue. The safety indicator point is dropping just before the fire (bullet) pictogram. I can actuate the trigger from this position. If I rotate it more it will not stop.

I extended the pin spring to get a positive pressure but that is not solving the issue. I think the (80%) completed lower maybe off. I tried the selector on two other (80%) completed lowers from the same outfit and all three have the same issue.

Im not kscott but this may help

Which LPK did you use? There are selector switches that are designed to rotate less than 90 degrees but usually an aftermarket selector. Does the selector seat when you get in into the position you have shown in the picture and continue to rotate with additional pressure? Check your slot on the selector and pull the grip off and check the detent. It may not be seated all the way in and not properly engaged in the slot of the selector. Ive dealt with a handful of 80s that had a burr or two in the hole for the selector detent. With the detent in, apply a little bit of pressure on it with a punch. It may just get passed a burr and snap right into place.

[RP1911]

All parts are PSA. When I rotate it stops as in pic. With pressure, I can get it past the fire. Going back to safe takes considerable pressure to rotate left.

[Jason25]

All parts are PSA. When I rotate it stops as in pic. With pressure, I can get it past the fire. Going back to safe takes considerable pressure to rotate left.

Put a drop of oil into the slot itself and work it back and forth. Sounds like its getting snagged on something. Standard PSA lpk should rotate 90 degrees and engage into place.

[kcstott]

I can only say that it looks like your selector hole is out of spec. To far forward. that would also make your selector stop where you are saying do to the detent hole not being on center of the selector hole.
Pull your selector and see if the detent hole is centered in the bottom of the selector hole. It should be obviously perfect or not.

If that is in fact the case then your lower needs to be plugged and redrilled on proper location. You can either plug and redirill the selector hole or plug and redrill the detent hole. The detent hole is the easier fix

[RP1911]

Fixed it. First I tried different selectors, springs and detents. Once I figured out that any of the three combinations was having the same issue. I took an unstretched spring and cut a bit of the spring (2-3) coils off. Problem solved in that the selector now moves freely between safe and fire. However, it still stops from going 90 degree to verticle.

[Jason25]

huh... your selector or detent hole may indeed be out of spec. post a pic if your not satisfied

[RP1911]

Yeah not satisfied. Will discuss with vendor.

[kcstott]

was this an 80% or 100% receiver??

[RP1911]

Kcstott,

Thanks, I'll check for that.

[RP1911]

Kcstott and Jason25,

You guys are great. Three out of 4 of the lowers have detent holes that are off center. The 4th one is correct as I tested it with the same selector, detent and I modified spring.

They were 80%.


I owe you guys a drink or two.

Best regards,
RP