I put my lowers together over the past month and noticed on my buffer tubes that somehow a ridge has formed between the castle nut and the rest of the tube. Across the three lowers, they all have the ridge but to varying degree of severity. I’m gunna try and post a pic of it below. Is this normal?
Edit: Also, the buffer tube is LaRue (I’m still waiting for their CS to handle my problem, it’s been 4 months). QD Plate is Impact Weapons (I think it’s the best QD plate and the CS from Earl is fantastic). Castle Nut torqued to spec.
Also, I ran my fingers inside the buffer tube and it doesn’t seem to affect the inside of the tube.
I’m betting the ridge was already there from manufacturing, you just didn’t notice it before. LMT tubes have a similar ridge, although the location is slightly further back.
Milspec tubes have thinner walls, and the threads are pressed on and are full depth.
Commercial tubes are weaker material, and have thicker walls, and the threads are cut, but are smaller and do not fully engage the threads of the lower receiver.
No clue about details on material, construction, or production for LaRue RE extensions, what I posted is for standard milspec or commercial tubes.
You have to define what you mean by mil-spec if youre gonna go down that road.
When a company (other than Colt) says “mil-spec” on their buffer tubes, theyre really only referring to OD.
Not even BCMs tubes are true “mil-spec.”
TRUE mil spec tubes are forged 7075 (or perhaps impact extruded?), with rolled threads, straight back, with drain hole, 4 position, hard coat anodized, with dry film lube applied.
Few tubes are made that way, so the industry genrally accepts the term “mil-spec” as applied to buffer tubes to simply refer to outside diameter of the portion of the tube the buttstock fits on.
EDIT TO ADD- I just took one of my BCM lowers out of the safe, because curious. It has rolled threads, but it appears to have been turned on a lathe, has a slight ridge. Doesn’t matter, don’t care.
Your tube is not Mil-Spec, but your tube is fine. Go shoot your gun and don’t worry about it.
Yeah, my worries about it not-being fine were put to bed on your first post. I’m not concerned about cosmetics, just function. I appreciate all your knowledge.
Yeah, my text tubes are going to be BCM or Vltor. If I could find a colt, cool. Going with larue was a mistake, i.e. expensive with no function improvement.
Not sure if it’s 100%, but if they are tube OD they I assume they are cut. If the threads OD are greater than tube OD, I assume they are rolled on. The end of the thread where it stops and goes to the tube is different as well.
Hopefully someone with more technical knowledge chime in.
If you have two to compare it’s obvious. Sometimes you can tell on the last few threads if it is rolled as the top of the thread will be “M” shaped. Unfortunately, since this looks sloppy, most quality places turn the last five or six threads flat. Also, if the thread ends suddenly - it’s cut. Rolled threads usually fade out over a quarter turn or more.
But honestly, most places that make mil-spec diameter extension roll the threads in, its easier than cutting them, even the “mil-spec” UTG extensions have rolled threads.
If you are really worried about such things, just buy from a well known and respected seller…
And the ones I’ve seen up close and in person look rolled. Just because they machined the last few threads to clean them up and put a slight step in it doesn’t mean the threads aren’t rolled . . . (see below)
