View Full Version : Purchasing A New AR- What now?
I wanted to post this in light of some things that I have seen over the last 8 months or so that I have been traveling around and teaching my 2 day AR15 armorer course. What finally prompted it was a carbine that was brought to the class I just finished in Santa Clara, CA at Reeds Indoor Guns.
One of the students brought a mix of parts and some complete carbines. All of them were California compliant. In particular one of them was a S&W. The person wanted to FSB and barrel nut removed in order to install a low pro gas block and rail system. Once the FSB came off and we started to remove the barrel nut, one thing became immediately obvious. Once we placed the barrel nut wrench and breaker bar on the nut and started to apply downward pressure, the barrel nut came right off.
There is no possible way that it was torqued correctly. This could in fact have an impact on the accuracy of the weapon.
It is extremely important that prior to purchasing and walking away with an AR you inspect it as closely as possible. In no particular order are some things you need to check.
1. FSB- Is it F-marked (where appropriate) and is it tight?
2. Carrier- Check the carrier closely. Look at the stakings and the screws. If possible disassemble it and check the components. (I have seen plenty of so-called staked carriers that were not torqued and staked correctly and we broke them loose with ease).
3. Gas tube- Check to see if the gas tube is straight. If possible disassemble the bolt carrier group and insert the carrier into upper (stripped) and see if there is binding.
4. Lower- Visually examine the FCG and see if it the parts appear to be assembled correctly. You can do a basic function test of the FCG while it is in this state.
5. Lower receiver extension- Check the lower receiver extension and look to see if it is staked. Grab the stock and attempt to rotate the tube. If it moves, you know there there is an issue.
Over the last approx. 7 months since the Great Gunpocalypse of 2013 started, it's not hard to imagine that there are plenty of AR's being cranked out and not all of them correctly.
It's a good idea to thoroughly check the weapon BEFORE you pay and take delivery.
Good info for basic carbine newb (and not so new?!:secret:)
This is all good stuff.
I'm glad I went with my father to check out a few rifles he was considering during the craziness. I followed through with alot of the same checks. Needless to say there is a reason he ended up with the carbine he did, and saved him from the other two abortions.
Thinking about the rifles I own what would be an indication(s) that the barrel nut is not torqued properly? Do you recommend we have them checked? Thanks.
That's up to you. If it's a Colt, Bravo, LMT, DD, or Noveske I wouldn't be very concerned.
Thinking about the rifles I own what would be an indication(s) that the barrel nut is not torqued properly? Do you recommend we have them checked? Thanks.
5. Lower receiver extension- Check the lower receiver extension and look to see if it is staked. Grab the stock and attempt to rotate the tube. If it moves, you know there there is an issue.
Sorry if this has been covered a lot of times, but if the extension is staked but can be rotated a little bit, can it still back out?
Inkslinger
06-27-13, 20:42
Great post. I couldn't agree more. The problem is most people purchasing their first AR would have no idea to look for any of those things. I know, I was one of those people many moons ago. I didn't even own a computer. Internet, what's that? I would have figured with the wealth of knowledge available today with the click of a mouse, uninformed consumers would be a thing of the past. Sadly that's not the case. People will compare a dozen versions of the same flat screen TV, but guns are all the same.
I can't say you're preaching to the choir because you're dead on about the recent posting onslaught. If people are taking your class you would think they are ahead of the curve. That also makes the fact they're showing up with shitty AR's puzzling. You must be a patient man in the real world Gunz. Or, you end your day quivering in the shower muttering DPMS, Bushmaster, Spikes...;)
Not likely. What will happen is that the movement will start to wear the tube (alignment tab of the endplate) and then tube will get jacked up.
Sorry if this has been covered a lot of times, but if the extension is staked but can be rotated a little bit, can it still back out?
ridgerunner70
06-27-13, 23:25
Is the torque for the barrel nut 30-60 inch pounds?
Is the torque for the barrel nut 30-60 inch pounds?
30-80 ft lbs.
horseman234
06-28-13, 06:37
Thank you, IG
I have learned much since finding this site, including the inspection steps you have listed, but it's great to have a list in one spot for reference.
This thread should be a sticky.
Very good reminder.
since the influx and flooding of countless AR makers this year to fill the shortage/panic, there are many things to consider before putting $$ towards a good rifle.
As I say nowadays, "Not all rifles are created Equal."
This needs to be stickyed, with some good pics of each thing discussed.
In my opinion, the most important thing to look for in the lower is that the hammer spring is on top of the trigger pin. This is a very common mistake in lower assembly, I remember on TOS for a long time it wasn't even covered in their troubleshooting guide, and the question would get asked once a month.
Plumber237
06-28-13, 12:56
Another vote for making this a sticky thread, I have a few friends that were looking into getting an AR without knowing anything about the platform. These simple guidelines would be huge for someone who can disassemble an AR but isn't sure what to check for before buying.
This is a good check list and probably should be covered at the outset when teaching a carbine class for new armorers or new shooters.
This thread also covers a lot of this. Unfortunately the pics disappeared during a server or site upgrade.
https://www.m4carbine.net/showthread.php?t=79448
That's up to you. If it's a Colt, Bravo, LMT, DD, or Noveske I wouldn't be very concerned.
My Noveske/Magpul MPL MOE Carbine arrived with no gas tube roll pin and the barrel nut torqued just past finger tight.
Problem children like these can sneak through anyone's processes because of the human factor, so the advice to do a quick check of all the parts is definitely warranted.
the weapon BEFORE you pay and take delivery.
I might add check BEFORE you shoot the weapon if you did not check it properly when purchased.
My Noveske/Magpul MPL MOE Carbine arrived with no gas tube roll pin and the barrel nut torqued just past finger tight.
Imagine that, a human somewhere along the line made a mistake. :nono:
I guess this is one of the reasons I decided to build my own carbine. I bought top quality parts from trustworthy vendors, then triple checked or better while assembling that everything was done correctly. I'm sure I paid more for my weapon than if it had come out of a store, not even including tools and time.
I'd still like to have a NIB 6920 though...
I'd like to hear any tips for torquing the castle nut and keeping the receiver tube straight. I've tightened a few and noticed the tube trying to rotate causing the latch plate "key" to dig into the tube threads.
Any tips? Use the stock to help keep the tube from rotating?
I'd like to hear any tips for torquing the castle nut and keeping the receiver tube straight. I've tightened a few and noticed the tube trying to rotate causing the latch plate "key" to dig into the tube threads.
Any tips? Use the stock to help keep the tube from rotating?
Crank the tube all the way to the right. Put the stock on the tube and hold it with one hand while torquing the nut with the other. If you want my OCD suggestion put the stock on the shortest setting you can so the entire length of the channel on the stock is in contact with the rail on the RT. (done so you aren't torqing on a small edge of the channel, like I said an OCD detail). Then if the stock needs to come over for perpendicular, eyeball the turn and you're good to go.
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