'Didn’t get a response on a separate thread so I decided to generalize the question. Have any of you ever personally witnessed an AR or M4/M16 have a failure to function as a result of damage to the receiver extension?
If so, do you know who made it and what cause the problem, ie bent tube, stripped threads, etc…? I’ve heard from several second hand sources that this is an issue, but I would like some first hand feedback. I want to know if this is an issue that is anything to be concerned about.
Can you be more specific? I have seen failures due to the castle nut/ end plate not being staked. One thing that I have noticed is that the MILSPEC tubes fit the rear of the receiver better than commerical tubes. Some of the commercial tubes seem loose even after they have been screwed in all the way.
More specifically I mean failures that are do to stripped threads, bent tubes, cracked aluminum, etc… Things that I would expect from abusing the carbine, not necessarily from improperly staked castle nuts or the like. Thanks.
ETA:
Being an armorer, have you had to replace any receiver extensions? What were the circumstances?
I had to replace quite a few. This was due to the factory or someone else unknown putting Loc-Tite on threads and not staking the nut. They were also potentially overtightened and when I went to remove them to clean things up and do it correctly many of the threads were either stripped or got stripped in the process.
AS I pointed out above. I have seen lots of commercial tubes that had some play to them after they were screwed into the receiver. I have never seen that in the MILSPEC tubes that I have dealt with. And for the slight cost difference I just don’t see why one wouldn’t buy a MILSPEC tube.
I’ve seen one broken at receiver after a Humvee backed over it.
Seen countless number at classes and on the range that failed due to improper or lack of staking (well, let’s call it around 20 instances over the last 10 years). Usually the buffer retaining pin works lose and into the action.
You can hit Tards on TOS with facts like this and they’ll still argue that having a mil spec RE is a snob issue. :rolleyes:
If you have a gun that’s strictly a range toy, a commercial tube might be just fine.
But if you might climb and obstacle, deploy from a vehicle, or get knocked down fighting or training… the strongest RE possible might be the way to go. :eek:
Thanks very much for all the responses. Do any of you recall if the receiver itself was also damaged in any of these cases, or just the extension?
I have the M4-7 Heavy Duty RE from ACE. It has an overbuilt lug that extends the full length of the tube, and an aluminum block that butts against the receiver to resist any bending. When I chose this RE I thought it the strongest one available, but I have since learned a few things that has me second guessing my decision; it has commercial threads, it is made of 6061 aluminum, and it is undersized compared to other commercial spec stocks. I am curious if the added material is enough to actually be a stronger RE given that it is 6061 instead of 7075. I also have concerns about the threads’ engagement staying intact (although it feels very solid, that is really subjective).
I’m fairly rough on all of my guns (not neglectful, just abusive) and I am planning to take some classes this year and dedicating a lot more time to learn to run my carbine better. I wanted a set up that I wouldn’t have to worry about. Am I being paranoid here? If this were a normal commercial tube I would replace it in a heart beat (I have already replaced my upper, BCG, charging handle, optics, etc. after finding this sight last year). I’m just not sure how it stacks up and if it warrants an upgrade.
I’ve considered replacing my current setup with an EMOD kit, but I’m not sure if that’s a step back or forwards. I’m this close to ordering a Sully stock and not worrying about the RE issues. Any feedback would be very appreciated, and thanks again for all of the helpful information that you’ve given (which really helps a lot of us get on the right track).
I had the exact ACE HD RE that you posted in the pic for a while. Held up next to a standard commercial RE, it does appear to be pretty robust… I don’t know that it’s any better than a milspec (in fact I doubt it), but it appears to be of similar strength and better than a commercial. The main detraction in my eyes is the attachment mechanism - I’m not huge on the gusset versus a properly installed castle nut - but that could be just me. (I know I wrecked the first one during install and ACE sent me out another free of charge…) ACE claims that the gusset increases strength, but they’re the mfr, so that’s expected…
FWIW, I removed it only because I installed a CTR on the rifle, and used the provided milspec RE. I built a patrol rifle for a local deputy who was in a money crunch, so I donated several parts (handguards/BUIS/etc) that I had laying around for that build. He’s still running the ACE setup on his patrol rifle and he’s hamfisted as Hellboy.
ETA: To answer the original question… I’ve seen RE’s damaged/destroyed - but they’ve all been issed (mil) carbines subjected to ridiculous force, run over by victors, etc, as posted above. ONE of them may have been a commerical tube tweaked in a collision, but I believe the force would have ruined any RE, including a Rifle RE in an A2 stock… I can’t recall ever seeing any RE damaged by common use, mil or commercial… That being said, for the cost differential, I’d personally stick with milspec tubes for cheap insurance… I did have a shooting partner who mortared a commercial RE countless times due to a shitty upper build with sticking chamber, but I don’t know if it’s still holding up or if he eventually replaced the rifle/RE…
I have never been able to find a real reason as to why there are commercial stocks and RE’s when it appears to me that there is little to no cost savings from a manufacturing perspective.
What purpose does the commercial stock and receiver extension serve?:blink:
Are these numbers yield or ultimate strength? This is good info but its important to realize that a receiver extension is rarely subjected to tensile stress. I would be more concerned with its ability to be loaded in compression or shear. Moment of inertia and bending stress would also be important.
