Db1986 Posted November 25, 2017 Report Share Posted November 25, 2017 I have an aero precision m5e1 with a 18 inch ballistic advantage Hanson barrel. I'm having ejection problems with 2 different aero precision bcg in this barrel, the casings basically fall out instead of being thrown out. If I use either of the bcgs I have in my other 16 inch barrel the casings are thrown out instead of being falling out. I also have marks where my bcg hit my buffer tube with the 18 inch Hanson barrel, with the 16 inch this doesn't happen. My bolt locks back every time on single loads also. If anyone has any ideas what could be wrong I would appreciate it. Quote Link to comment Share on other sites More sharing options...
edgecrusher Posted November 25, 2017 Report Share Posted November 25, 2017 What is the build sheet? Did you change anything other than the barrel? Are you sure the gas block is aligned properly? Is it the correct gas tube? How about some pics? Quote Link to comment Share on other sites More sharing options...
Db1986 Posted November 25, 2017 Author Report Share Posted November 25, 2017 It is all aero precision parts except buffer tube which is a standard carbine mil spec buffer tube with aero precision 308 carbine buffer and spring. Gas block is staked and perfectly lined up from the manufacturer. Yes it's definitely the proper gas tube. It seems to be getting enough gas, it would lock the bolt back every time I fired just one round. Could it be a chamber issue? Spent casings just fall out with both bcgs I have. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted November 25, 2017 Report Share Posted November 25, 2017 You have a recoil system issue in that 18" gun. List your recoil system parts for the 18" gun. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted November 25, 2017 Report Share Posted November 25, 2017 29 minutes ago, Db1986 said: I also have marks where my bcg hit my buffer tube with the 18 inch Hanson barrel, with the 16 inch this doesn't happen. This spelled it all out, right here. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted November 25, 2017 Report Share Posted November 25, 2017 Go grab a chunk of the Intro Section while you're at it, and tell us about yourself. Quote Link to comment Share on other sites More sharing options...
Db1986 Posted November 25, 2017 Author Report Share Posted November 25, 2017 My recoil system is mid length gas tube with aero precision 308 carbine spring and buffer. If I'm not mistaken the Hanson profile barrels are slightly undergassed, I'm baffled why my spent casings are ejecting properly out of my ballistic advantage 16 inch with mid length gas system, but not out of the 18 inch. The 16 inch also doesn't cause the bcg to strike to buffer tube. The gas port holes are both extremely close in size in the 16 and 18 inch barrel. Quote Link to comment Share on other sites More sharing options...
edgecrusher Posted November 25, 2017 Report Share Posted November 25, 2017 Are you using the same lower for both? What’s the gas port size of the 18”? Also measurements on spring and buffer. Just because you bought a kit doesn’t mean it’s correct Quote Link to comment Share on other sites More sharing options...
Db1986 Posted November 25, 2017 Author Report Share Posted November 25, 2017 Yes same lower for both, .0781 is the gas port for the 18 inch. I will get exact measurements of my 308 buffer and spring when I go to my shop. I know the buffer is shorter than my ar 15 and the spring is longer and a lot stiffer. I'm almost positive that the spring and buffer are correct. Could the gas system cause my casings to not eject properly if my bolt locks back after firing only one round each time? Or could the chamber be the issue? Quote Link to comment Share on other sites More sharing options...
shepp Posted November 25, 2017 Report Share Posted November 25, 2017 4 minutes ago, Db1986 said: Yes same lower for both, .0781 is the gas port for the 18 inch. I will get exact measurements of my 308 buffer and spring when I go to my shop. I know the buffer is shorter than my ar 15 and the spring is longer and a lot stiffer. I'm almost positive that the spring and buffer are correct. Could the gas system cause my casings to not eject properly if my bolt locks back after firing only one round each time? Or could the chamber be the issue? Count your coils and measure your spring while your at it Quote Link to comment Share on other sites More sharing options...
Db1986 Posted November 25, 2017 Author Report Share Posted November 25, 2017 The spring has 29 coil and the buffer is 2.5 inches Quote Link to comment Share on other sites More sharing options...
98Z5V Posted November 25, 2017 Report Share Posted November 25, 2017 Cool. What's the internal depth on the receiver extension?... They ONLY way your BCG is going to hit your buffer tube, and the lower receiver ears, is because the BCG is contacting those parts before the buffer can do it's job - which is bottom out in the receiver extension.Your recoil system is not working right. When I asked for recoil system details, you listed gas system details - those are two separate things that work together, but they accomplish two completely different things. IF you have an issue in your recoil system (and you do, or you wouldn't be hitting the buffer tube - and the lower, if you look close), so... IF you have an issue there and this is only coming up on the 18" gun - then you have a gas system issue on that 16" upper - because it doesn't have enough gas to throw that BCG into the buffer tube and lower... Make sense? Quote Link to comment Share on other sites More sharing options...
Db1986 Posted November 25, 2017 Author Report Share Posted November 25, 2017 Yes that makes perfect sense and I'm going to measure the internal depth of the reciever extension. Would that cause my spent casings to not eject properly? On the 16 inch upper they eject fine. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted November 25, 2017 Report Share Posted November 25, 2017 Photo's of where the BCG is hitting the Lower Receiver or Receiver Extension ? Quote Link to comment Share on other sites More sharing options...
survivalshop Posted November 25, 2017 Report Share Posted November 25, 2017 If the 16" works on this Lower , its an issue with the 18" Upper , probably Gas related , but I wouldn't rule out a fitment or Friction issue . How far does the Gas Tube protrude into the Upper Receiver , photo of that if you can get it also, just curious . Any rub makes on the 18" that you don't see on the 16" Upper ? What are the finishes of the Two Upper Receivers , Are they Different ? Quote Link to comment Share on other sites More sharing options...
98Z5V Posted November 25, 2017 Report Share Posted November 25, 2017 For what it's worth, OP, I bought ONE AP carbine receiver extension, for my first AP 308 build. Weird shiit happening with the cycling, so I checked it out - 7.100" internal depth. For a DPMS-based 308 recoil system, running a 2.5" long 308 carbine buffer, it needs to be running in an exact AR-15-lengthed carbine receiver extension - 7.000" internal depth. When I had that problem, I shitcanned the whole DPMS-based carbine extension business, went all Armalite AR-10 carbine recoil system, and never looked back - with flawless operation. I've built 3 other 308AR carbines since, and they all run the Armalite AR-10 Carbine recoil system. No guesswork, no diagnosis - if I have a cycling issue, it's not in the recoil system, it's something else. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted November 25, 2017 Report Share Posted November 25, 2017 Just now, survivalshop said: If the 16" works on this Lower , its an issue with the 18" Upper , probably Gas related , but I wouldn't rule out a fitment or Friction issue . How far does the Gas Tube protrude into the Upper Receiver , photo of that if you can get it also, just curious . Any rub makes on the 18" that you don't see on the 16" Upper ? What are the finishes of the Two Upper Receivers , Are they Different ? Not necessarily - hear me out on this one... With the 18", he's hitting the BCG during cycling. If the recoil system was correct, that wouldn't be happening. No other way around that, it's 100% accurate. Same lower. Something is up with the recoil system in this lower, or the 18" wouldn't be slamming it. 16" upper on that lower - it functions... with an issue in the recoil system... So, is that 16" undergassed, and it's not slamming the BCG? But just maybe almost there?... It's undergassed, and just missing that contact of the BCG and the tube... You put a proper recoil system in this lower, so BCG contact is impossible - like it's supposed to be - and I'll bet that 16" doesn't run as well then... Quote Link to comment Share on other sites More sharing options...
DNP Posted November 25, 2017 Report Share Posted November 25, 2017 Or they'll both run ok. I think 98 has got it. It doesn't matter how overgassed a gun is, it shouldn't hit the BCG. There's an issue there and it's in the tube/spring/buffer and nowhere else. Once that is fixed, you'll get to see what else is up with the gun. Quote Link to comment Share on other sites More sharing options...
Db1986 Posted November 25, 2017 Author Report Share Posted November 25, 2017 When your measuring the internal depth of the buffer tube are you measuring the whole tube or past the detent and threads? Quote Link to comment Share on other sites More sharing options...
98Z5V Posted November 25, 2017 Report Share Posted November 25, 2017 Topside. Internal depth from the top of the base/back, to the very edge of the top where the tape comes out. I'll use a wooden chopstick, pushed into the top back, and knife-mark that thing right on the very edge where it comes out of the tube. Measure that chopstick from the end, up to your mark. You can't get an accurate measurement on the bottom of the tube (inside), because some of these tubes have a protrusion or "flare" there, to further capture or almost enclose the detent. Quote Link to comment Share on other sites More sharing options...
Db1986 Posted November 25, 2017 Author Report Share Posted November 25, 2017 Looks like internal depth of the reciever extension is around 7.1, thanks for the info 98z5v. I changed it out for a POF 7 position buffer system kit. I fired it but I'm still having ejection issues. Also My bcg is not hitting the buffer tube anymore and I still have lock back. Both bcg I have are aero precision black nitride, they both work fine in the 16 inch black nitride ballistic advantage barrel, but in my 416r ballistic advantage stainless Hanson barrel with nickel boron barrel extension the spent shell casings are still falling out. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted November 25, 2017 Report Share Posted November 25, 2017 8 hours ago, 98Z5V said: Not necessarily - hear me out on this one... With the 18", he's hitting the BCG during cycling. If the recoil system was correct, that wouldn't be happening. No other way around that, it's 100% accurate. Same lower. Something is up with the recoil system in this lower, or the 18" wouldn't be slamming it. 16" upper on that lower - it functions... with an issue in the recoil system... So, is that 16" undergassed, and it's not slamming the BCG? But just maybe almost there?... It's undergassed, and just missing that contact of the BCG and the tube... You put a proper recoil system in this lower, so BCG contact is impossible - like it's supposed to be - and I'll bet that 16" doesn't run as well then... Makes sense & is why I asked for a photo of what is being hit , also if it had makes from the 18" Upper , how would you know the 16" wasn't hitting . . 0.781" Port in the Barrel , doesn't seem too large for a Mid Length Gas system , not sure , I only run Rifle length gas systems on 308AR's . How did you tell that the BCG is no longer hitting the Lower Receiver ? Color the marks ? The Ejected Brass issue could be several things , tight or rough Chamber , over/under gassed , improper Head Space , improper Chamber dimensions , issues with Bolt components (Extractor , Ejector systems ). I just had an old AR 15 Build that started barely Ejecting fired brass & it was a weak Buffer Spring , changed it & it went back to Ejecting properly , just goes to show you all the components in the Rifles Action contribute to its working . I believe there is more to this then just the Buffer System . Quote Link to comment Share on other sites More sharing options...
Db1986 Posted November 25, 2017 Author Report Share Posted November 25, 2017 I feel like there is more to it also, the POF buffer tube I have has a feed ramp so I wouldnt be able to tell if the bcg was hitting it. I could tell every time the 18 hit, I fired 60 rounds out of the 16 and the old buffer tube didn't change, I checked every few rounds I fired. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted November 25, 2017 Report Share Posted November 25, 2017 4 hours ago, survivalshop said: I believe there is more to this then just the Buffer System . I think so, too. One thing at a time - next, I'd go to a known good buffer spring for these DPMS-based 308 carbines, and use a Sprinco or Tubb Flatwire. After that, I think we will be chasing some gas issues. If the 16" upper is ejecting just fine with both BCGs, but not in the 18" with both BCGs, I don't think there's an extraction or ejection issue. Quote Link to comment Share on other sites More sharing options...
Db1986 Posted November 25, 2017 Author Report Share Posted November 25, 2017 I'm using the spring and buffer that came with the POF kit it is a rifle spring with an ar 15 size buffer. Its a good deal stiffer spring. Quote Link to comment Share on other sites More sharing options...
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