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Posted: 12/9/2014 8:24:05 PM EDT
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I recently put together a .308 and I am getting a malfunction I need to correct. Everything is PSA PA10 except for the barrel, which is a Rainer select. After I got it assembled I shot 2 boxes of federal xm80 with no problems at all. I started shooting some Remington premier match 168gr and I started getting ejection problems. The empty casings were getting stuck in the ejection port, but they were turned around backwards, and a live round is in the chamber. This happens about 2 out of 5 shots. I don't know how this is possible. The only thing I could think of was the brass bouncing off the shell deflector just right and getting stuck that way because the shell deflector was getting pretty dinged up. So I put in a H3 buffer to change the direction it was ejecting, but its still doing the same thing (lower came with a H buffer). I tried Speer gold dot 168gr and hornady sst 165gr and they all had the same problem. Does anybody have any idea how this is happening?
Here is a mock up of the malfunctions I was getting. 
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| drill bits and a caliper will get you close.... a action that works to fast will not have time to do all the operations properly i.e. get the case all the way out of the ejection port. xm80 is just ball ammo right witch has lower presser that worked so higher presser rounds leads me to think its over gassed or under spring powered.(recoil spring) cases can bounce all sorts of weird places sum you have to see to believe.. |
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Quoted:
drill bits and a caliper will get you close.... a action that works to fast will not have time to do all the operations properly i.e. get the case all the way out of the ejection port. xm80 is just ball ammo right witch has lower presser that worked so higher presser rounds leads me to think its over gassed or under spring powered.(recoil spring) cases can bounce all sorts of weird places sum you have to see to believe.. Yeah that's kinda what I was thinking. My next plan was to get an adjustable gas block. I just wanted to check with you guys first before I dropped another $70. |
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What extension tube are you using?
If we're talking about H2 and H3 buffers, there's a problem here. AR10 carbines need a special extension tube, i.e the ArmaLite Inc. or Vltor A5 if you're using AR15 carbine buffers. If you have a standard carbine buffer, you need a short AR10 buffer. |
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Quoted:
What extension tube are you using? If we're talking about H2 and H3 buffers, there's a problem here. AR10 carbines need a special extension tube, i.e the ArmaLite Inc. or Vltor A5 if you're using AR15 carbine buffers. If you have a standard carbine buffer, you need a short AR10 buffer. PSA buffer tubes are for standard carbine length buffers. They actually had a problem with early units where they sent out the shorter 308 buffers and BCGs were hitting the receiver. Now I am pretty sure they send the 308 buffer tube and a stabdard H buffer in kits. |
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Quoted:
What extension tube are you using? If we're talking about H2 and H3 buffers, there's a problem here. AR10 carbines need a special extension tube, i.e the ArmaLite Inc. or Vltor A5 if you're using AR15 carbine buffers. If you have a standard carbine buffer, you need a short AR10 buffer. Its got the correct tube. Like Hking said, PSA ships it with a longer tube and standard H buffer. |
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Measure the length of the extension tube and let us know what that dimension is please.
If that is the length of the A5 or ArmaLite AR10 carbine tube (between the length of an AR15 carbine and AR15 rifle), then you should be GTG on using AR15 carbine buffer lengths. Next thing is to diagnose the malf. Stove pipes like that are either under-gassed, or too high of a cyclic rate from over-gas or under sprung, under buffered. They can also be sharp extractor lips, but you usually see a 90 degree stove pipe or double in those instances. The 90 degree stove you have has the neck in first, which makes me suspect super fast carrier velocity/high cyclic rate. |
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Quoted:
Measure the length of the extension tube and let us know what that dimension is please. If that is the length of the A5 or ArmaLite AR10 carbine tube (between the length of an AR15 carbine and AR15 rifle), then you should be GTG on using AR15 carbine buffer lengths. Next thing is to diagnose the malf. Stove pipes like that are either under-gassed, or too high of a cyclic rate from over-gas or under sprung, under buffered. They can also be sharp extractor lips, but you usually see a 90 degree stove pipe or double in those instances. The 90 degree stove you have has the neck in first, which makes me suspect super fast carrier velocity/high cyclic rate. My tube is 7-3/8 to the receiver. I counted the coils on my buffer spring and its correct too. Its longer than an AR15 spring. So if my cyclic rate is too high, and I already have a H3 buffer, would getting an adjustable gas block and turning it down fix the problem? |
| I've never seen a stovepipe with the forward portion captured.......Anyway, pull the charging handle fully to the rear and look into the ejection port. The front of the bolt should not go farther back than the rear of the ejection port. If it does you will see half circles on the fired cases where they are contacting the rear of the port upon ejection. This can cause the base of the empty case to be spun around and not get out of the rifle. Another indication of this condition is weak ejection with the fired cases just barely getting out of the rifle. Getting back to the bolt travel. If it goes back too far in the upper, it can be shimmed with a rubber washer under the buffer spring or by swapping buffer tubes, buffers until it gets right. Just remember, it has to go back far enough to allow the bolt catch to work. Make sure the buffer spring doesn't stack. Let us know what you find. |
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My tube is 7-3/8 to the receiver. I counted the coils on my buffer spring and its correct too. Its longer than an AR15 spring. So if my cyclic rate is too high, and I already have a H3 buffer, would getting an adjustable gas block and turning it down fix the problem? Quoted:
Quoted:
Measure the length of the extension tube and let us know what that dimension is please. If that is the length of the A5 or ArmaLite AR10 carbine tube (between the length of an AR15 carbine and AR15 rifle), then you should be GTG on using AR15 carbine buffer lengths. Next thing is to diagnose the malf. Stove pipes like that are either under-gassed, or too high of a cyclic rate from over-gas or under sprung, under buffered. They can also be sharp extractor lips, but you usually see a 90 degree stove pipe or double in those instances. The 90 degree stove you have has the neck in first, which makes me suspect super fast carrier velocity/high cyclic rate. My tube is 7-3/8 to the receiver. I counted the coils on my buffer spring and its correct too. Its longer than an AR15 spring. So if my cyclic rate is too high, and I already have a H3 buffer, would getting an adjustable gas block and turning it down fix the problem? What barrel length and gas system length? What's your port diameter? I don't see any of that data posted yet. It will help out if this info is included in the OP. If it was mine, I would do a detailed troubleshoot build from the start, to include tuning the extractor, radiusing the ejector, ensuring the ejector channel is clean and free of burrs or debris, correct ejector spring is installed, not an AR15 ejector spring, plus up the extractor with 2 O rings, clean the bolt face square, de-edge the firing pin hole and extractor shelf, as well as ejector channel opening (for brass treatment, not reliability). I wouldn't trust parts at the price point offered from PSA to get any of this right, especially the AR10 ejector spring vs. AR15. That could be the issue right there. The problem is we'll be dealing with these issues week after week, month after month, year after year, into the foreseeable future as long as they are made cheaply. You need the Brownell's bolt disassembly tool to check the ejector spring. Extractor should not have sharp edges on the lips, that bite into the rim. |
| ...just my $.02- since the rifle is so new, try lots of lube on the BCG; I mean dripping lots. I had a similar problem with my DPMS mk 12. I read about the lube thing on their site or a post. I figured before trying anything else, I'd give that a go. Needless to say, the lube worked and after a few hundred rounds, the bcg and upper were lapped and I haven't had a problem since. I went back to my normal amount of lube after the initial break-in. |
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Quoted:
Yeah that's kinda what I was thinking. My next plan was to get an adjustable gas block. I just wanted to check with you guys first before I dropped another $70. Quoted:
Quoted:
drill bits and a caliper will get you close.... a action that works to fast will not have time to do all the operations properly i.e. get the case all the way out of the ejection port. xm80 is just ball ammo right witch has lower presser that worked so higher presser rounds leads me to think its over gassed or under spring powered.(recoil spring) cases can bounce all sorts of weird places sum you have to see to believe.. Yeah that's kinda what I was thinking. My next plan was to get an adjustable gas block. I just wanted to check with you guys first before I dropped another $70. A friend of mine had a similar issue. case in action jams. He also had bent rims and over pressure signs on the brass. His barrel was a Black Hole Arms barrel (IIRC). He got an adjustable gas block, turned down the gas and all his problems went away. I think he was using a standard AR carbine RE with the dpms short buffer. I just finished my build using a Rainier Match barrel (and VLTOR A5 receiver extension, Armalite AR10 carbine spring and H3 buffer). I went ahead and installed an SLR Rifleworks adjustable gas block. Out of 15 clicks of adjustment total (0 = off, 15 = wide open) I was able to turn it down to the 6th setting from off and get it to function 100%. With my silencer, I could turn it down to the 4th click. So, wide open, I would have been over gassed. I don't know if that would have caused me any issues, but it does show that there is plenty of room for tuning if needed. |
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Quoted:
A friend of mine had a similar issue. case in action jams. He also had bent rims and over pressure signs on the brass. His barrel was a Black Hole Arms barrel (IIRC). He got an adjustable gas block, turned down the gas and all his problems went away. I think he was using a standard AR carbine RE with the dpms short buffer. I just finished my build using a Rainier Match barrel (and VLTOR A5 receiver extension, Armalite AR10 carbine spring and H3 buffer). I went ahead and installed an SLR Rifleworks adjustable gas block. Out of 15 clicks of adjustment total (0 = off, 15 = wide open) I was able to turn it down to the 6th setting from off and get it to function 100%. With my silencer, I could turn it down to the 4th click. So, wide open, I would have been over gassed. I don't know if that would have caused me any issues, but it does show that there is plenty of room for tuning if needed. Quoted:
Quoted:
Quoted:
drill bits and a caliper will get you close.... a action that works to fast will not have time to do all the operations properly i.e. get the case all the way out of the ejection port. xm80 is just ball ammo right witch has lower presser that worked so higher presser rounds leads me to think its over gassed or under spring powered.(recoil spring) cases can bounce all sorts of weird places sum you have to see to believe.. Yeah that's kinda what I was thinking. My next plan was to get an adjustable gas block. I just wanted to check with you guys first before I dropped another $70. A friend of mine had a similar issue. case in action jams. He also had bent rims and over pressure signs on the brass. His barrel was a Black Hole Arms barrel (IIRC). He got an adjustable gas block, turned down the gas and all his problems went away. I think he was using a standard AR carbine RE with the dpms short buffer. I just finished my build using a Rainier Match barrel (and VLTOR A5 receiver extension, Armalite AR10 carbine spring and H3 buffer). I went ahead and installed an SLR Rifleworks adjustable gas block. Out of 15 clicks of adjustment total (0 = off, 15 = wide open) I was able to turn it down to the 6th setting from off and get it to function 100%. With my silencer, I could turn it down to the 4th click. So, wide open, I would have been over gassed. I don't know if that would have caused me any issues, but it does show that there is plenty of room for tuning if needed. I think im going to try the gas block first before I start messing with extractors or anything else. |
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