ironmonster

Screwjack the guys here are super helpful. I have learned a lot about the .308 platform in the few months I have been hanging around here. Like Wash said its not rocket science, but there are lots of known issues about using various parts together. My recommendation would be to put together a "dream list" and post it and get some feedback about compatibility

I can tell you I have both the AIM's Surplus and Aero precision BCG's and they are for all practical considerations identical. I have a Rainer Select barrel in one of my rifles and it works better with only of my bolts than the other barrel which is a Aero Precision. Did you check or have someone check headspace on your bolt/barrel?

That is from the top of the shoulder to the top of the buffer, as I was measuring if there was enough room for the spring to compress without compressing to solid so the lip wouldn't count. Overall it's almost exactly 2.5" (2.507") Yeah, it might be a bit before I can see how they run but with the Slash's buffer and spring it no longer is possible for the carrier to come in contact with the receiver or extension. As long as they run good I'll be golden. I am still curious about other carriers, what is it about the Aero that is different?

Mmmm. That pic is right side up on my phone... Sorry.

Close up pic of the Nazel, you can see my 210 ton Williams White forging press behind it. Just those two machines weigh close to 18 tons.

The clean side and dirty side of my shop, the big forging hammer out in the middle is a 102 year old Nazel 4B, a 350 lb hammer that strikes 150 blows a minute. I have 5 power hammers and 4 hydraulic presses. In the back of the crowded pic you can kind of make out my Bridgeport, lathe and shaper. Like I said I am no Machinest, but I can get by enough to make my own tooling for the hammers and build simple parts. I also manufacture a line of blacksmith tools under the Quick and Dirty name www.quickanddirtytools.com www.monstermetal.org

I assume it's just the way Aero's are made? That is the UBR tube and you will notice at the top the tube is pretty close to flush. As far as close and blacksmithing goes... Well you could say I am a far cry from a machinest. If I don't like the way something fits I get a bigger hammer. If I still don't like the way it looks I hit it with the hammer until I do. My theory is if you can't fix it with a hammer you got an electrical problem.

Ok first off try and keep the "I fucking told you so" to a minimum. I got one coming and I know it. I thought the spring was bottoming because best I could force it down over the buffer it seemed to run out of buffer before running out of spring. Using something else to manually compress the spring it's clear it's not. Both the Tubbs and Slash's spring measure 2.073" compressed. From the top of the rim of the buffer to the end of the bumper it measures 2.242". So there is about 5/32" difference or the size of a trigger pin. So it comes close to fully collapsed, but doesn't The one pic is to show the mark where the carrier hit the receiver on the rifle with the UBR The pics with the carrier pushed in the receiver extension show that "$2" I am talking about (that really probably more like $1.50. In any case one the Tubbs/DPMS crashes, the Slash's buffer and spring has like 7/16" clearance fully compressed. So I am interested to see how other carriers compare, it's obviously a combination of the Aero carrier, standard RE, Tubbs/DPMS that is a fail. I am assuming if others check carriers it will show either a different overall lenght, different length to the shoulder or both.

And 8 quarters is probably an exaggeration, but not much of one. The difference is three eights to 7/16 of an inch so it's probably more like 6 to 7 than seven-eight

Both the standard carbine and the PWS are the same inside length (depending on which you measure, As I reported I found them to vary .156 between the 6 I had on hand but even with the shortest one the Tubbs/DPMS combo crashes with the Aero carrier) And I am not saying it needs 8 quarters in there to work, it only needs 2-3 to not crash and probably 4 to give in a bit of clearance and still not over travel. what I am saying is it needs 7-8 quarters in there to give as much clearance between the top of the buffer tube and the sectional change on the carrier as you get with no quarters in the tube and Slash's buffer and spring. Thats the other thing. I did do all this. If you read back a few posts I talked about measuring the quarters, measuring the buffer tubes trying to figure out how much I needed. You say I missed the point, but I did all the work. I'll take some pictures. One thing I am wrong about. I keep saying the Tubbs spring is collapsing to nothing, I am saying that because out of the gun if you collapse the spring the overall length is greater than that of the DPMS buffer. (best I could determine, I'll verify today) Thinking about it more though in my rifle it is probably not collapsing all the way because the carrier is hitting first. If you put quarters in there though then you reduce the inside measurement enough that the spring collapses. Either way the buffer bumper cant come in contact with the rear of the receiver extension because the collapsed length of the spring is greater than that of the DPMS buffer I will build a simple rig to measure the various springs collapsed and report overall lengths of the buffers and report back later today to verify im not talking out my ass here. I just want to understand, I want it to work yes but I also want to understand why it is or isnt working. In any case its this combination of parts, I am sure of that. The Tubbs spring and DPMS buffer sounds like it works find with other carriers/receivers fine. It might be because the shoulder is in a different spot on other carriers but I still think if that is the case the spring is bottoming before the buffer bumper touches (not that its suppose to, but that it is) I'll know for sure here in a bit after I do some experimenting

But I did swap out the PWS receiver extension for a standard mill spec one at one point. With the receiver extension out of the rifle (either of them, the PWS or a Mil-spec one) if you put the tubbs spring and DPMS buffer in there and then compress it with the carrier where the carrier changes diameter it comes in contact with the tube. With any 7" receiver extension, the tubbs spring, DPMS buffer and Aero carrier it will crash. And I get what your saying, But you got to admit by stacking up quarters in there your not figuring out why those parts dont work in this case. I dont need any quarters with Slash's heavy buffer and spring, I would have needed to stack 2 bucks in there with the DPMS buffer and Tubbs spring to get the same clearance and the spring still would have been collapsing to solid. Why? There is not that much difference in the length of the buffers. There is something else in play that I am missing. I think I figured out a simple way to show & measure the collapsed height of the springs. Tomorrow when I get to the shop I'll take some pictures.

I guess I should also ask, I am assuming you are running the .308 Tubbs spring right? Because the 5.56 spring would allow the DPMS .308 buffer bumper to touch the end of the receiver extension before it "bottomed out" but I cant imagine its got enough push to keep the system happy.

What carrier are you using with the Tubbs and the DPMS buffer? What lower? Out of curiosity measure the distance from the back of the carrier to where it gets bigger? See if that is any different than the Aero? Also would you take your carrier and just push it in the receiver extension and see where it bottoms? What is the distance from the top of the buffer tube to the sectional change in the carrier when it is fully collapsed? I have the two .308's, One had the PWS tube, the other has a UBR with the included tube. Both had DPMS buffers and Tubbs springs, both of them the carrier hit the buffer tube boss (the one with the UBR was slight, but it still hit) It may be a combination of the Aero components with the Tubbs/DPMS stuff. There is no doubt though with what I have the Tubbs spring collapsed is bigger than the length of the standard DPMS buffer. There is no way for the bumper to touch the end of the receiver extension as the spring locks up first. I actually took the PWS tube out (I was surprised that the damage did not lock it in there, but it didn't) and installed a standard mil spec tube on my receiver and it changed nothing. I even went though all of the ones I had to find the shortest inside measurement and the carrier still bottoms with the Tubb's/DPMS set up. I have probably $500 worth of Tubbs springs in my other AR's. I use the buffer springs, ejector and extractor springs in a lot of guns. In my 5.56 guns they have run perfect. I am a fan, I was real hesitant to give up the Tubbs spring in the .308 but the combination of it and the standard DPMS buffer simply is not functional. 98Z5V wanted me to stack quarters up in the buffer tube, while that would have kept the carrier from crashing it is a cover up fix ignoring the real issue which is a spring and buffer that was incompatible with the Aero carrier and receiver. The spring would have just come to the fully compressed state that much sooner, still a crash with the buffer bumper never making it too the quarters. Its kind of like everyone on the internet telling you to drill out your gas port when you gun wont run. Yeah, you can overgass it and force it to function, but there is a reason why it wont run with the proper amount of gas, why not fix the actual problem? An AR with an 1/8" gas port will run with a plethora of problems, right up until it destroys itself.

? Whaaaatt?? You don't stake the inside of the tube to the receiver? Your obviously not up on the latest tactical trends. All the "Real" operators have been doing it for years... ;-)

See the thing is though, at least 85% suggestions where wrong, just looking at what was in front of me I could see that. I don't know much, but I can stand in front of my gun, read what someone wrote, look at my problem and say "Nope, Not it". Doesn't mean I'm not listening. I don't know why exactly, but the combination of the standard DPMS buffer and the Tubbs spring is the problem. As you said in another post the coil does not bind (run out of travel) before the buffer hits,, well it was and did. That was a combination thought to work with a standard carbine RE and at least with a Aero upper and BCG it doesn't. And yeah, I did take offense. I took offense because I was listening and working on solving the issue. I had looked at everything everyone had said and took to heart what seemed to be relevant. Those things you yelled at me for not listening to? They didn't solve my problem. I don't have any problem with they way you handled it, I thought it was abrasive and unnecessary but hell about half of life is abrasive and unnecessary. If I knew you better maybe I wouldn't have taken it that way, but I don't. Alls well that ends well, on with life ;-)

So I got my heavy buffer parts today so I got the rifles out and did some tinkering. First off the PWS buffer cannot be screwed in another rotation. It is as far as it can physically go (it bottoms before you can make another revolution) As you can see there is a huge difference in the Tubbs spring vs the heavy buffer spring. The Tubbs spring will not even go on the heavy buffer as the diameter is larger. So with the buffer tube out of the rifle with the Tubbs spring and standard DPMS buffer the carrier can and does go into the tube fare enough for the sectional change to make contact. With the heavy buffer and spring it bottoms with about 5/16 from the top of the buffer tube to the sectional change on the carrier. So the problem I was experiencing is physically impossible with this new combination. Now this is a little confusing to me as the buffer itself is only about a 1/8 longer, not long enough to account for the 3/8 difference (5/16 + the 1/16 it crashes) The rim seems to be shorter on the heavy buffer but in my mind that works against, not for increased clearance. Also with the heavy buffer and spring it will collapse far enough that the bumper on the buffer will hit before the spring collapses to solid, it won't with the DPMS and Tubbs spring. It's going to be a bit before I can go shoot these but I am 99.99% sure I am golden at this point.

just goes to show how complex such a simple system can be. There is nothing too it, yet everything is critical.

Man I really appricate all the effort you put into this. Outstanding, top notch and super cool.

That is outstanding, and really interesting. Tomorrow I'll have to do some comparison . For a .308 I dont have anything but the Tubbs spring, but my assumption is even though its longer it will compress smaller because its nature.

I ordered one, And I ordered two heavy buffers and corresponding springs. Between the two Im guessing no more crash, I still need to figure out is I am seriously over gassed though. I would not think the Rainer barrel would be anything out of the ordinary for gas port size. Its a 18" mid gas system.

Just out of curiosity I dug out the few AR's I have here and measured bolt over travel (using my eyecrometer) Out of these 13 the distance from the bolt face to the bolt catch varies a lot. The least being an 1/8" or less, the most being a strong 5/16"s (in a factory built Noveske light Recce lo-pro) I am making the assumption that the carrier/buffer is bottoming before the charging handle runs out of stroke but that may not be the case.

Just out of curiosity I dug out the loose buffer tubes I had laying around in my parts. I came up with 6. There are two that measure 6 7/8 from inside bottom to end of threaded lip One that measures 6 15/16, two that measure a dead 7" and one that measures 7 1/32". All measured to the longest point of the tube lip ( a couple have protruding lips to engage the detent, the longest point always determining the buffer system travel as it is screwed up to the detent That is a overall variance of .156" Two quarters stacked up measure .135, three quarters .202

See, I'm smiling ;-)

Thanks Matt. I'm a big boy. Can can take a bit of abuse before gather up my toys and run home crying. It just struck me out of the blue as I feel like the issue was already worked though and workable solutions proposed, steps taken to rework things and then BamB! I'm a clueless fucking idiot!

Dude, really? You think anyone would listen too you when you treat them like that? You may be king shyte of turd mountain around here but if you really have the answers giving them like that is a way to make sure no one listen. Being a dick, even if it is warranted (which I cant see that it is) is no way to get your point across. I have listened to each and every suggestion and implemented and investigated all of them and I am not an idiot. I own 17 AR's and built probably 40, I am not completely clueless. I own a fab/blacksmith shop and have a basic machine shop. I know how to run a fucking tape measure. The PWS tube is dead nuts 7" inside, the other tube is 6 7/8". I understand I need less internal depth, That is why I made a spacer. I understand the buffer weight, length and spring tension/length affect how the carrier cycles which is why I bought a heavier buffer and the recommended spring. When I said I need the carrier to be shorter, that was a poor choice of words and something that I did not think through, which is why i immediately posted a follow up statement saying I understood that was wrong. What was going on in my head was that I needed less space in the system between the back of the carrier and the bottom of the buffer tube, and that more space in the system would exacerbate the problem. That came out as "shorter carrier" but thats not really what I meant. I came looking for suggestions, I am new to the .308 platform, asking questions and verbally thinking through things by posting questions and responses. Show me one example of information posted here that I have ignored? There is nothing posted here I did not take to heart and consider. The only arguments I have made have been to try and clarify the problem and question weather there was any merit to the idea.