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Page AR-15 » Build It Yourself
AR Sponsor: bravocompany
Posted: 12/11/2016 4:09:25 AM EDT
I went to my local Gun Dealer and purchased a buffer tube, buffer and buffer spring. I did most of my research before building my AR. Anyways, I asked if the buffer spring was suitable for a Carbine length rifle. They said, "yes it will fit". Didn't think nothing of it as I know they are way more knowledgeable than me. I installed buffer tube to the correct spec, castle nut to correct torque and staked it using a spring loaded center punch from Harbor Freight. I then tested to see if bolt locked back with empty magazine. Bolt didn't lock back. So I tried w/o magazine and tried to lock bolt back by pulling charging handle back and then engaging bolt catch but wasn't locking back. I sat there, being my first build ever I was nervous. I looked at it for minutes and and hours. Then I got an Ar15.com. Looked around to see if anyone had same issue. Some said Magpul magazines, bolt catch etc. So I then researched about the buffer spring. In my research I found out that there are different size buffers springs. Anyways, my buffer had 44 springs or twist or circles. According to what I read 44 twists/circles was for a rifle w/ longer barrel than a 16". And a carbine was around 40 to 38. So I decided to cut about 4 full circles from buffer spring. Now, buffer springs ain't that expensive which really didn't matter if I messed it up. But I did one by one, cut one off it left it 43, nothing bolt still not locking back, then 42, still nothing. I got to 40........ and wallah bolt locks back!!!! I noticed before this bolt was not going back far enough to catch on bolt catch. So the tension from the spring being soo long caused that to happen relieving tension by removing 4 springs or circles. Now my bolt locks back. Took it to the range to fire the first 300 rounds ran perfect and bolt locked every time after last round was fired. That was my solution. Try it if you have same issue.

Thanks again. Sorry for the long story did. It want to leave out much.
Link Posted: 12/11/2016 7:49:37 AM EDT
[#1]
Looks as though your dealer wasn't more knowledgeable than you after all.
Link Posted: 12/11/2016 8:08:01 AM EDT
[#2]
If that response of "it will fit" is a direct quote......technically they were right, but not completely honest. You were able to install the buffer, and if you shot the rifle with it, it would have cycled. The unreliability (towards them) is that it wasn't the ideal part, because the last round BHO didn't function.
Link Posted: 12/11/2016 8:21:50 AM EDT
[#3]
Spring length and barrel length are independent of each other. Carbine tubes need carbine springs. Rifle tubes need rifle springs.
Link Posted: 12/11/2016 8:47:02 AM EDT
[#4]
You're right.  It works.  Carbine springs aren't that expensive (but it may take awhile to get one if you order it).

I had the same issue several years ago.  I ordered the tube, spring, and stock from the same vendor.  When I installed it the bolt wouldn't lock back.  I pulled the buffer spring out of one of my other carbines and sure enough, they'd sent me a rifle buffer spring instead of a carbine buffer spring.

I did smooth the edge/cut and put that end in the back of the tube.  I doubt there are instructions/rules for that but it seemed the best place/way to orient it.

Good luck with your build.  There will be more.
Link Posted: 12/11/2016 8:49:01 AM EDT
[#5]
Always do your research and dont trust "gun guys" most of them working in shops are fucking idiots and NOT "gun guys"
Link Posted: 12/12/2016 8:00:24 PM EDT
[#6]
And now is the time to buy a proper carbine length spring and replace your chopped down one as they really are pretty inexpensive.  Doing so will ensure you have the proper spring tension of which you likely don't have at the moment.
Link Posted: 12/13/2016 2:53:58 AM EDT
[#7]

I think I'd pull the buffer and spring out, put the buffer in the spring, and compress the spring on a flat surface to see if the spring was still going into coil bind, or the end of the buffer makes it all the way to the flat surface.

Link Posted: 12/13/2016 9:05:15 AM EDT
[#8]
The buffer should be able to bottom out in the receiver extension without getting coil bind in the action spring.
Link Posted: 12/13/2016 3:50:58 PM EDT
[#9]
Hahaha! Your right!
Link Posted: 12/13/2016 3:52:43 PM EDT
[#10]
I did shoot the rifle as is. That's when I realized the bolt wasn't locking back! Hahah! I ended up letting them know and they actually replaced my chopped one for a carbine length at no charge!!
Link Posted: 12/13/2016 3:53:13 PM EDT
[#11]
Thanks!
Link Posted: 12/13/2016 3:54:37 PM EDT
[#12]
Thanks! I did a pretty clean cut as well and filed it smooth. But I ended up going back and they replaced it for a carbine length with no problem.
Link Posted: 12/13/2016 3:55:12 PM EDT
[#13]
Yes, looking forward to a 300 blackout build now.
Link Posted: 12/13/2016 3:57:01 PM EDT
[#14]
It was the owner hahah! They replaced it with no questions asked. They actually did have different buffer springs. Didn't ask why they told me it would fit hahah.
Link Posted: 12/13/2016 3:57:45 PM EDT
[#15]
Thanks. I went back to the Gunshop and they replaced it for a carbine length buffer tube, no questions asked.
Link Posted: 12/13/2016 3:58:42 PM EDT
[#16]
I ended up getting a carbine length tube from gunshop! Thanks!
Page AR-15 » Build It Yourself
AR Sponsor: bravocompany
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