Buffer tube threads are BARELY long enough??

[SuperSneakySniper]

Hey guys,

I've recently put a rifle length buffer tube on an AR i'm building out. It's the first time I'm using a rifle-length buffer tube on an AR, and what the heck? The threads BARELY allow me to screw it on far enough to keep the buffer detent in place, I swear if I wiggle the detent hard enough it may pop out. Any one you guys know of a rifle style buffer tube that will hold it a bit more...... positively? Y'know, with threads that will go on and hold down the detent a little better?

 

[07yzryder]

picture? my rifle length tube holds it down just like a carbine length.

and just to be sure since we troubleshoot the stupidest stuff first. you depressed the extent down while threading right?

 

[GH41]

The receiver extension (tube) should cover about 1/4 of the buffer retainer hole in the receiver when screwed snugged down. If it doesn't something is out of spec. Hopefully it is the tube and not the receiver.

 

[SuperSneakySniper]

Okay ill try to get a picture up. Yes i made sure to depress the detent while tightening down the receiver extension. I sure hope the reciever isnt whats out of spec XD its an expensive reciever from F1. The tube is a DPMS i got for like 20 bucks.

 

[Waorani]

I'm sure it happens but after dozens of rifle extensions (including many DPMS) I've never seen one that was out of spec. Is there any chance someone messed with the tube for some reason? When fully tightened the lip barely captures the detent so it really is just "barely long enough."

 

[SuperSneakySniper]

Okay here are some pics, unfortunately my friend is also building an AR so I gave him my detent and spring so that's no longer in the receiver for these pics, but you can see the relationship between the tube and receiver here:

 

[GH41]

Let me ask a dumb question... You do have the tube screwed directly into the receiver? You aren't using an end plate like you would on a carbine RE?? If the answers are yes/no you have a problem. It would be easy enough to try another tube or measure yours and reach out to someone here for comparison. I am almost willing to bet the receiver spec is the problem. The tube would have to turn another full rotation to be where it needs to stop.

 

[SuperSneakySniper]

I'm not using an end plate. Dang, I REALLY hope it ain't the receiver! Well, is anyone able to tell me what the proper length of the threaded part of the tube is supposed to be? I have calipers here I can use to measure, from end to stop plate.

 

[GH41]

I don't have a rifle tube to measure. For grins... Look at the retainer pin hole from directly above the receiver. It should be noticeably angled front to rear. Maybe they can't read prints and drilled the hole plumb. If it's drilled 90 degrees to the top of the receiver it's too far forward. I can dig up a print if you don't understand what I am saying.

 

[hlee]

Ok, really dumb question... what are you planning to use for buffer/spring? If, by chance, you are contemplating the JP silent capture spring, the retainer is unnecessary and generally a pain to have installed. So, there is a work around even if the lower is not drilled correctly.

 

[SuperSneakySniper]

I'm not %100 sure what you're saying regarding the angle of the drilled holes, but I don't think I see any angled drilled holes. Damn.

Ok, really dumb question... what are you planning to use for buffer/spring? If, by chance, you are contemplating the JP silent capture spring, the retainer is unnecessary and generally a pain to have installed. So, there is a work around even if the lower is not drilled correctly.

Huh... I was contemplating using a JP SCS. This is for a 3-Gun competition AR so that would fit the bill. Though I still wish I could use the regular stuff. Man... For a receiver set that cost over $600 you'd expect the job done right. If this problem keeps heading in this direction, I'll have to contact F1 and see if they've got anything to add/help.

 

[2ndamendfan]

Do you have another AR handy to compare with? Swap tube to another retriever? By the looks of the pictures the whole is to far forward. I agree with above, I think your receiver is the issue.

 

[Waorani]

Extension doesn't need to go in much more. Is it fully tightened? If so cheapest thing would be to try another extension. I've never noticed the detent hole to be drilled at an angle but maybe it is. Never gave it a thought and not where I can look at one now but would have assumed it was 90 deg.

 

[2ndamendfan]

After looking at a couple of mine i think your reciever is probably okay. At least by the location of the hole. What if the reciever is to thick/deep/long in the extension.

 

[SuperSneakySniper]

hmm.... Shoot, anyone with calipers able to measure their receiver thread lengths and/or tube thread lengths? I'll see if I can measure one of my forged lowers

 

[2ndamendfan]

Measured a few. I would think that .500 is spec as i got.
.502
.489
..504
.501
.486
.490
that is various manufacturers, 2 billet the rest forged

 

[2ndamendfan]

That is at the top across the flat where the charging handle rides. Front to back "thickness".

 

[GH41]

If my math is correct the back of the hole should be .437 +/- .002 from the back of the receiver.

 

[GH41]

Extension doesn't need to go in much more. Is it fully tightened? If so cheapest thing would be to try another extension. I've never noticed the detent hole to be drilled at an angle but maybe it is. Never gave it a thought and not where I can look at one now but would have assumed it was 90 deg.

I cannot be drilled 90 deg. The center of the hole is .565 forward of the back of the receiver. The hole dia is .255. The top of the threaded part is .5 long. Almost 1/2 of the hole is shadowed by the top of the receiver. Print shows hole drilled at 6 degrees.

 

[Waorani]

I cannot be drilled 90 deg. The center of the hole is .565 forward of the back of the receiver. The hole dia is .255. The top of the threaded part is .5 long. Almost 1/2 of the hole is shadowed by the top of the receiver. Print shows hole drilled at 6 degrees.

Thanks, drill clearance was only reason I could think of that it would be at an angle but I've never noticed before.

 

[SuperSneakySniper]

If my math is correct the back of the hole should be .437 +/- .002 from the back of the receiver.

Uh oh. My calipers say the back of the hole is around .453 from the rear of the receiver.......

Oooookay fellas, so uhh what about the JP Silent Capture Spring? Has anyone tried it without the detent retaining it? No drawbacks to that setup right? Cuz I might have to go the "buffer detent delete" route.

 

[SuperSneakySniper]

Measured a few. I would think that .500 is spec as i got.
.502
.489
..504
.501
.486
.490
that is various manufacturers, 2 billet the rest forged

Okay, mine measures about .508 a bit on the longer side, but not enough to see the differences i'm seeing. However, I did measure distance from rear of hole and rear of receiver, and now I'm thinking the stacking tolerances f-ed me.

I'd still like to see a measurement of the length of threaded section of a rifle buffer tube though, and any information regarding the JP Silent Captured Spring to forgo the buffer detent would be awesome as well.

 

[ballisticdaddy]

I'd still like to see a measurement of the length of threaded section of a rifle buffer tube though, and any information regarding the JP Silent Captured Spring to forgo the buffer detent would be awesome as well.

I run the JP silent capture system in all my gas guns and they recommend removing the detent and spring to allow it to operate smoothly. If you haven't fired a rifle with this system you might be surprised as to the absence of cheese grater effect against your cheek, I would highly recommend.

 

[SuperSneakySniper]

I run the JP silent capture system in all my gas guns and they recommend removing the detent and spring to allow it to operate smoothly. If you haven't fired a rifle with this system you might be surprised as to the absence of cheese grater effect against your cheek, I would highly recommend.

Well consider my spirits lifted! If its recommended by JP to not even deal with the detent/spring then this problem is solved (though not the way I would have liked it to be solved, it is solved nonetheless).
Thanks guys! Can't wait to try it out.