View Full Version : buffer tube /detent issue
msedward43
07-20-23, 22:02
ok guys, I have a quick question. I have a factory Sionics lower that I pulled out of storage to pair with one of their Patrol III uppers that I picked up and noticed that the buffer tube seemed to not cover nearly as much of the bufer detent as my other ones. Sending off a message to Josh over at Sionics to see what he has to say about it, but I just wanted to have you guys weigh in and see if my OCD is just going into overdrive, or whether there really isn't enough coverage of the buffer pin
I don't really build my own lowers so all I know is that my other Sionics/BCM/SOLGW lowers cover about 50% or more of the exposed buffer pin while this one seems to only catch part of it.
70593
The problem when they stack like that is that if you turn the receiver extension/buffer tube one move revolution it will often be right up against the pin itself. That lip you can see on the end of the extension could be adjusted (material removed) so that you would be able to turn one more revolution, maybe.
I'd want more on there, but that's me. Could be that it will work forever.
I'm sure Sionics will try to make you happy.
titsonritz
07-21-23, 00:16
The problem when they stack like that is that if you turn the receiver extension/buffer tube one move revolution it will often be right up against the pin itself. That lip you can see on the end of the extension could be adjusted (material removed) so that you would be able to turn one more revolution, maybe.
Personally, I wouldn't go cutting on my RE, an offset buffer retainer is a better solution to that problem.
https://gallowayprecision.com/offset-buffer-retainer-for-AR-15-rifles
https://truenortharms.com/ar15_default_store_view/offset-buffer-retainer.html
I believe you'll want to check the internal depth of the buffer tube. From SOTAR.
https://www.youtube.com/watch?v=eAuTHPdUchU&t=397s
I have one or two like that. Sometimes that’s how it happens. There’s not enough room for another turn so you get just the lip. I’ve never had any problems out of lowers like this. I wouldn’t worry about it. If it really bothers you, you could try multiple other receiver extensions to see if one screws in a little more over the buffer retainer.
msedward43
07-21-23, 10:19
I believe you'll want to check the internal depth of the buffer tube. From SOTAR.
https://www.youtube.com/watch?v=eAuTHPdUchU&t=397s
it actually passed the quarter test.
ViniVidivici
07-21-23, 10:43
Me, I don't like seeing them like that. I also want as much thread engagement between RE and lower as possible.
What I've done in similar situations, is undo things, and turn the RE in one more turn. If it doesn't play nice, I file a small round notch to accommodate the pin.
Me, I don't like seeing them like that. I also want as much thread engagement between RE and lower as possible.
What I've done in similar situations, is undo things, and turn the RE in one more turn. If it doesn't play nice, I file a small round notch to accommodate the pin.
This is the way. Small round file does the trick. I forget who's RE was set up this way but it had a tongue with a notch in it. Might be PWS?
This is the way. Small round file does the trick. I forget who's RE was set up this way but it had a tongue with a notch in it. Might be PWS?
That I know of in alphabetical order: 2A Armament, Aero Precision, B. King’s Firearms, Dark Hour Defense, Patriot Ordnance Factory, Primary Weapons Systems, V Seven.
Me, I don't like seeing them like that. I also want as much thread engagement between RE and lower as possible.
What I've done in similar situations, is undo things, and turn the RE in one more turn. If it doesn't play nice, I file a small round notch to accommodate the pin.
This is the way. Small round file does the trick. I forget who's RE was set up this way but it had a tongue with a notch in it. Might be PWS?
Would you not potentially run into the gas key contacting the receiver by doing this though? You're essentially shortening the RE by turning it in, no?
Would you not potentially run into the gas key contacting the receiver by doing this though? You're essentially shortening the RE by turning it in, no?
That is going the opposite direction; you would shorten the stoke and increase the gap between the carrier key and the receiver.
That is going the opposite direction; you would shorten the stoke and increase the gap between the carrier key and the receiver.
Oh, duh.
That is going the opposite direction; you would shorten the stoke and increase the gap between the carrier key and the receiver.
I would not feel good about shortening the buffer stroke. Not sure what a full rotation of the RE would yield, but I'd be concerned about it much more than leaving the RE as is in the pic.
msedward43
07-21-23, 13:22
I would not feel good about shortening the buffer stroke. Not sure what a full rotation of the RE would yield, but I'd be concerned about it much more than leaving the RE as is in the pic.
yeah, that's why I'm not taking out the receiver and tightening it myself. it passes the 2 quarter test already, any more and it would be over shortening the stroke IMO... I'm going to wait and see what Sionics replies back with first.
I would not feel good about shortening the buffer stroke. Not sure what a full rotation of the RE would yield, but I'd be concerned about it much more than leaving the RE as is in the pic.
The way I look at it is that if you can only turn the RE in far enough to barely make contact with the retainer pin then the stroke is probably on the long side to start with. However OP said in that config it passes the two quarter test, which has me wondering if the RE is out of spec itself.
The way I look at it is that if you can only turn the RE in far enough to barely make contact with the retainer pin then the stroke is probably on the long side to start with.
Could be. But based on the pic, I'm doubful you could expect another full turn.
However OP said in that config it passes the two quarter test, which has me wondering if the RE is out of spec itself.
I'm betting the RE is a little shy of material in the front by the detent hole. But I wouldn't go as far as to change/replace it if it were my gun.
That I know of in alphabetical order: 2A Armament, Aero Precision, B. King’s Firearms, Dark Hour Defense, Patriot Ordnance Factory, Primary Weapons Systems, V Seven.
I've only seen the PWS enhanced buffer tubes with the notch. Always thought it was a good idea.
msedward43
07-21-23, 17:57
I've only seen the PWS enhanced buffer tubes with the notch. Always thought it was a good idea.
There is a downside to them. If you have a jam or your bolt carrier is locked back and won't go forward. With a regular buffer tube you can just unscrew it and take it off. However if it's jammed, that type with the little wings won't allow it to unscrew off of the detent. So you actually have to cut off the buffer tube to fix the problem
There is a downside to them. If you have a jam or your bolt carrier is locked back and won't go forward. With a regular buffer tube you can just unscrew it and take it off. However if it's jammed that type with the little wings won't allow it to unscrew off of the detail. So you actually have to cut off the buffer tube to fix the problem
Hmm, haven't seen a carrier stuck like that before. What would cause that?
msedward43
07-21-23, 18:10
Hmm, haven't seen a carrier stuck like that before. What would cause that?
not stupid common but I've seen it... for example, the buffer detent and spring coming out during fire and jamming up the front travel of the bolt lol.
the latest time I saw an issue was where the forward assist roll pin broke and jammed the carrier in the rearward position.
not like it's an every day occurence, but the buffer tube with the wings would make a siuation like that more problematic.
LMT makes kind of a trick receiver extension with a flange on one side to hold down the detent, I would also consider POF with their extra long "skirts."
I had an Anderson lower like that, LMT RE, all fixed up, gun be gone now.
msedward43
07-26-23, 13:40
since I live in Tucson, I was able to stop into Sionics locally and they fixed me up. problem solved
since I live in Tucson, I was able to stop into Sionics locally and they fixed me up. problem solved
Good to hear.
What did they do?
msedward43
07-28-23, 18:28
Good to hear.
What did they do?
adjusted the tube was all I was told. I'm happy as it's back to normal now.
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