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Buffer tube dimensions???

2K views 33 replies 2 participants last post by  joezx10r 
#1 ·
Can someone tell me the sizes please. Im gonna make my own tomorrow and need the Inside diameter and the length.
 
#2 ·
Joezx10r, The inside diameter on a used one I have laying around is 1.04", the total length is 10-3/32" measured with a tape measure. The threaded section is .490" long and the collar behind it is .135" thick. The nub at the back is .215" tall, .72" in diameter and has been reduced to .619" at the flats. The bore is 9-5/8" deep. Hope this helps.
 
#4 ·
If you're using tubing I'd just use 1" inside diameter tubing to make it easy. The head of the buffer is around .97" and the largest part of the bolt carrier that goes in there is around .93". I've been thinking of building a machined/welded version of a lower like in your avitar.
 
#5 ·
Yeah Im doing this so I dont need to buy that expensive tap. Sense my buffer mount comes off I dont see the need in tapping it the 1 3/16 16 they call for I could make the buffer tube and make the tap size a 18 cause we have that one at work.:biggrin: I dont know why more guys havnt built this type lower its so easy and you dont need any jigs to hold it while machining. http://www.geocities.com/elmgrove1765/project6/project6.html
 
#10 ·
Here's a pic. The spacer is used to make up the difference between an a1 and a2 stock. They just don't just make the tube longer for parts commonality and the tube can't be any deeper than what it already is or the top of the bolt where the key is will strike the back of the receiver and charging handle as it won't be stopped by the rubber bumper on the back of the buffer. The spacer is the same diameter as the buffer tube, the large diameter is .6" long, the nub at the back is .710" in diameter and .2" tall. The large diameter section also has a recess for the nub on the back of the buffer tube that is .215" deep and .73" in diameter.
 

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#11 ·
No spacer , You'll need a car buffer and a car length buffer tube or you'll get the same problem of the carrier striking the receiver. The car buffer tube also has a rib on the bottem that the stock locks into. If you want the car buffer tube specs let me know.
 
#13 ·
Ok, my car tube is .990" inside diameter, 1.163" outside diameter (there are two diameters, a comercial one and a mil spec one so check your stock when it comes), 7" deep bore, 7-1/4" long, the stock mounting rail is .480" wide, 4-7/8" long with the front 1/2" tapering to the tube, and .315" tall (1.478" total heigth). There is an inner slot that is 3-1/2" long, .325" wide, .145" deep. In the inner slot there are blind holes that the stock locking pin locks into. There is one at the front of the slot, one at the back, and between 3-6 total blind holes that are .3" in diameter and .160" deep as measured from the bottem of the slot they're in. I'll get some pics up in the morning. You may want to wait until you get your stock to make the tube as most of them rattle and I can't help but think if they were slightly oversize it would help.
 
#28 ·
Well my stock finally came in today and I measured the opening and its 1.200:censored: what the hell.:wallbash: So much for manufacturers dimensions.
What did your buffer tube O.D. end up at? Most of them are fitted pretty loose and have a rattle to them unless you get one of magpull ones. With the 1.163" buffer tube and 1.2" stock, I have roughly .037" of slop in the fit. Thats why I said yo may want to wait until you have your stock in hand to make it oversize as I hate that much slop in mine.
 
#14 ·
Here's the pics of my older 3 position car buffer tube. If you're going to thread the buffer tube, then you'll need to figure out a way to keep it from wanting to loosen up as the car stocks want to do. The original ones use a back plate to retain the rear takedown spring and detent. The plate has a key cut into it for a keyway cut into the bottem of the buffer tube threads. If you're going to pin/weld the buffer tube in you won't have to worry about this.
 

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#21 ·
I'd leave it stainless. You're not going to see another one I bet (unless you make it). Make sure you have a car length buffer and buffer spring before you go shoot it. The buffer limits how far back the bolt carrier can go to keep it from striking the back of the charging handle and front of the buffer tube area.
 
#22 ·
Thats one thing im worried about I have the car buffer and spring and also made the tube bore depth the the 7'' like you said but there aren't any threads its a press fit so theres no adjustment unless I take the shoulder back or shim the tube. Im going to weld a tab on the tube and drill/tap the buffer mount to retain it. I had to do this cause while milling the mount it pulled up and egg shaped the hole so I took it out to a larger size and matched the tube to it.
 
#23 ·
The 7" bore (for the car buffer) starts at the top front of your buffer tube retaining block. If you push your buffer and bolt carrier down the buffer tube, you should have around 3/16"-1/4" before the back of the gas key hits the buffer tube/receiver area. That gives the rubber bumper on the back of the buffer some room to squish down and slow the bolt if it gets that far back.
 
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