AR Sponsor
Posted: 6/10/2015 10:08:40 AM EDT
|
Had anyone had problems hand tightening their buffer tubes into their lower? I'm using an Anderson mil spec tube. It us screwing on super tight by hand. I've been able to get a few turns, but don't want to force it anymore.
Thought it may just be the anodizing between the two. I picked the tube up from Primary Arms and there were some pretty high reviews. Thoughts? Or do we need pics to diagnose? |
|
Have you checked the threads for burs? On both parts? And are you sure it's milspec spec and not a commercial tube? There were threads about this eariler and commercial tube not fitting. A commercial tube can be .020 thicker than a milspec tube.
Ref: http://www.cdsarms.com/images/MilSpec_vs_Commercial_Extension.jpg 
|
|
Quoted:
Have you checked the threads for burs? On both parts? And are you sure it's milspec spec and not a commercial tube? There were threads about this eariler and commercial tube not fitting. A commercial tube can be .020 thicker than a milspec tube. Ref: http://www.cdsarms.com/images/MilSpec_vs_Commercial_Extension.jpg http://www.cdsarms.com/images/MilSpec_vs_Commercial_Extension.jpg I could not find any burs and am sure the tube is labeled as mil spec. Link to the tube: https://www.primaryarms.com/Anderson_Manufacturing_Mil_Spec_Buffer_Kit_p/am-21-buffer-kit.htm |
| Do you have access to calipers? Measure the diameter of the threads and check off the picture. Mil spec should be 1.145 - 1.150 if it is commercial it will be 1.163 - 1.173. That's a big difference anywhere from .013 to .027. A milspec reciever will only take milspec tubes. A commercial would take both. Milspec buffers should have 4 holes on the bottom commercial should have 6. How maNY do you have? |
|
Quoted:
Do you have access to calipers? Measure the diameter of the threads and check off the picture. Mil spec should be 1.145 - 1.150 if it is commercial it will be 1.163 - 1.173. That's a big difference anywhere from .013 to .027. A milspec reciever will only take milspec tubes. A commercial would take both. Milspec buffers should have 4 holes on the bottom commercial should have 6. How maNY do you have? I do not have access to calipers. I'd hate to invest $35 at Lowe's on a set of digital calipers just to determine that my $25 (sale) mil spec tube kit is not mil spec ....but it is heading in that direction.... Can anyone confirm of a reasonably priced mil spec carbine length extension tube that will work? I'll likely be sending this one back and buying another one. |
|
Quoted:
Have you checked the threads for burs? On both parts? And are you sure it's milspec spec and not a commercial tube? There were threads about this eariler and commercial tube not fitting. A commercial tube can be .020 thicker than a milspec tube. Ref: http://www.cdsarms.com/images/MilSpec_vs_Commercial_Extension.jpg http://www.cdsarms.com/images/MilSpec_vs_Commercial_Extension.jpg So the more I look at this picture, the more certain I am that I have a mil spec tube. Outside tube diameter - this is where the stock slides on. (Note, this is not the outside thread to thread measurement and should have no impact on fit into the lower receiver.) Mil spec: 1.145-1.15 Commercial: 1.163-1.173 Outside thread diameter: Mil spec: 1.185 Commercial: 1.17 Thread Peaks vs tube: Mil spec: sharp defined peaks, larger than the OD of the tube. Commercial: rounded peaks, more or less in line with the tube. Correct me if I am wrong here, but the picture is saying the threads on a mil spec tube should measure 1.185, right? |
|
Quoted:
Had anyone had problems hand tightening their buffer tubes into their lower? I'm using an Anderson mil spec tube. It us screwing on super tight by hand. I've been able to get a few turns, but don't want to force it anymore. Thought it may just be the anodizing between the two. I picked the tube up from Primary Arms and there were some pretty high reviews. Thoughts? Or do we need pics to diagnose? clean up the threads with a thread chaser or steel wool, if you don't have a chaser. Then use a light film of oil before installing. Tech Tip. If you don't have a thread chaser, pick up a used buffer nut from the EE. Cut through it on an angle, you now have a thread chaser. |
|
So Primary Arms helped reach out to Anderson Manufacturing who sent a new tube, which fit tighter and whose threads were slightly larger than the first tube. My tube is within tolerances of all other tubes at Primary Arms from different manufacturers. I will for sure be buying everything from them going forward on my next builds!
I tried some light would and made sure the receiver threads were thoroughly cleaned. Wasn't able to get much further. I popped the tube in the freezer and was able to get another full turn after it was in there a few hours. I guess next step is the steel wool route. Should I rub down the receiver or buffer tube? Or should I try sending it back and seeing if Quarter Circle 10 could help running a reamer thru the receiver? |
|
**Update * *
I reached out to Russ at QC10 and after discussing the issue at length I took his suggestion and ordered a Vltor A5 mil spec buffer tube from Primary Arms, which arrived last night and threaded right in. I plan on taking similar measurements with digital calipers after work and will post pics tonight to compare against my Anderson tube. As both Russ at QC10 and Marshall at Primary Arms pointed out, even though the outside threads may measure within a certain tolerance, it also depends on how the threads are cut and that can also impact the fit. Just for reference, the OD of the Anderson threads was 1.183. Primary Arms measured 5 mil spec tubes from different manufacturers and they all measures between 1.180-1.185, so my Anderson tube was right in the middle. I would suggest not using an Anderson tube (even though they actually manufacture tubes for several different manufacturers per PA) and just start out with a Voltor tube on QC10 lowers and work from there. |
AR Sponsor