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Posted: 2/4/2013 8:38:51 PM EDT
[#1]
Is that a Polymer Lower? ETA stupid question i see you said it was right off the bat. I am going to guess you have a lower issue
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Posted: 2/4/2013 8:41:49 PM EDT
[#2]
Lower issue as in the lower its self or the buffer tube?
Yes it is a Polymer Lower. I don't think the lower is the problem, this is my first AR and my first AR build but The BCG should not be extending that far into the buffer tube where the gas key is striking it correct ? |
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Posted: 2/4/2013 8:43:26 PM EDT
[#3]
I'm guessing ether the lower or the buffer were out of spec causing the buffer to be bent downward. This would cause the back of the BCG to get pushed downward as it ran down the buffer which subsequently pushed the front of the BCG (gas key) to be pushed upward, maybe enough to be hitting the top of the receiver near where the buffer screws in.
See if you can determine if ether of them is bent anyway. |
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Posted: 2/4/2013 8:45:47 PM EDT
[#4]
my charging handle does have some wear on the side that faces the BCG.
but still what would cause the BCG over shoot and go further than it needs to, |
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Posted: 2/4/2013 8:48:50 PM EDT
[#5]
It appears your buffer tube may be to long or your buffer to short. The rear of the carrier should bottom out against the buffer (and the buffer against the back of the tube) before the carrier key impacts the rear of the receiver.
The easy temporary fix is to drop a few washers behind the spring/buffer and see if it fixes your problem. Long term (if this is the issue) you should replace the receiver extension/buffer.
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Posted: 2/4/2013 8:49:48 PM EDT
[#6]
Quoted:
I Shot the SOT upper no problem for about 30 rounds no jams or misfires. Then I switched to the Rguns upper I shot it for 3 rounds and it jammed, I cleared the jam and shot 2 more rounds and it jammed again. I switched back to my SOT upper and after 2 more rounds it jammed also. I put 3 more rounds through my SOT upper and it continued to jam. this part would lead me to think the upper is off and maybe causing not letting the bcg ride correctly -- either maybe touch high or something -- seeing how was no issues till you changed the upper edited: once you switched back the buffer was already messed up which would cause the SOT to mess up also --- how does the bcg fit or feel when putting it in the upper also where you say "my charging handle does have some wear on the side that faces the BCG" -- was this all new upper? any kind of trash or shavings from the wear (if its wore enough to cause that) |
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Posted: 2/4/2013 8:51:14 PM EDT
[#7]
The rear of my carrier does not bottom out before the gas key would touch the lower
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Posted: 2/4/2013 8:55:55 PM EDT
[#8]
What Part of the rifle actually stops the BCG from going to far, is it the buffer tube/spring/buffer or is it the bolt catch, what part of the system ensures the BCG does not over travel. Thanks again for all the responses.
I feel like alot of the parts we are buying right now are being rushed through productions and there may be alot of Quality Issues arises from the current climate. |
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Posted: 2/4/2013 8:57:23 PM EDT
[#9]
correct that by the time i switched back to the SOT the buffer it self was causing it to jam. and also removed some of the melonite finish from my BCG
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Posted: 2/4/2013 8:58:40 PM EDT
[#10]
Both are Brand new complete uppers purchased from Aim Surplus while I was following the uppers in stock thread on this forum :)
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Posted: 2/4/2013 9:01:29 PM EDT
[#11]
Here is a picture of my issue M4 and Colt BCG. You can see the gap where the carrier bottoms out before the carrier key can make contact.
 The marks on the rear of the carrier are from the deformed aluminum receiver extension after the carrier key impacted against it.
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Posted: 2/4/2013 9:04:17 PM EDT
[#12]
How long is that receiver extension, (buffer tube)? From your picture it appears to be about 8 inches long. I just measured 3 Colt tubes, one from the '60s, one from the '80s and one modern one. They are all 7.25 inches. I think your tube is too long.
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Posted: 2/4/2013 9:04:25 PM EDT
[#13]
Thank you
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Posted: 2/4/2013 9:04:55 PM EDT
[#14]
The interior of my tube measures at 7.25
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Posted: 2/4/2013 9:13:13 PM EDT
[#15]
7.25 inches was an external measurement. The internal measurement on a Colt tube is 7.0 inches. Your buffer should be 3.25 inches long.
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Posted: 2/4/2013 9:15:54 PM EDT
[#16]
the buffer is 3.25 but the internal measurement is 7.25 so there that might be what did it
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Posted: 2/4/2013 9:21:38 PM EDT
[#17]
just measured two buffer tubes and mine are 7.25 inside
edited: just measured another one and it is 7" inside --- buffers on all 3 are 3.25 |
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Posted: 2/4/2013 9:30:45 PM EDT
[#18]
im swapping out tubes to check the one mounted on a lower is 7" inside and it stops perfect just like above pic
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Posted: 2/4/2013 9:45:55 PM EDT
[#19]
okay well the 7" tube stop with plenty of room like in the pic above with the colt --- now the two buffer tubes that are 7.25 end up touching the lower with the bcg pushed all the way in -- wow is all i can say luckly i havent put these buffer tubes stock kits on anything -- was just fixing too in couple days when my lpk's came in
edited: i got the two 7.25 tubes from galati international a sponsor here so emailing them on it now |
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Posted: 2/4/2013 9:59:12 PM EDT
[#20]
Those long tubes work if you put between 2 and 4 quarters in the bottom of the tube or cut 1/4 inch off of the threads.
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Posted: 2/4/2013 10:04:03 PM EDT
[#21]
Maybe take out the spring, drop the buffer in there and then stick the BCG in till it bottoms out on the buffer and see if it touches. If it does then the buffer is too short for that tube.
"I think" 
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Posted: 2/4/2013 10:08:30 PM EDT
[#22]
Quoted: Maybe take out the spring, drop the buffer in there and then stick the BCG in till it bottoms out on the buffer and see if it touches. If it does then the buffer is too short for that tube. "I think" No. A standard buffer, (standard, H, H2, H3), is 3.25 inches long. The problem is the tube is .25 inches too long. |
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Posted: 2/4/2013 10:14:15 PM EDT
[#23]
these are the two i have that are too long http://www.galatiinternational.com/product/DARBT468B.html -- the one that is fine is http://www.galatiinternational.com/product/LERBT4BC.html -- all ordered through them
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Posted: 2/4/2013 10:16:18 PM EDT
[#24]
Quoted:
Maybe take out the spring, drop the buffer in there and then stick the BCG in till it bottoms out on the buffer and see if it touches. If it does then the buffer is too short for that tube. "I think" yea wont work -- buffer tubes are the issue -- hopefully i can get galati international to send me the correct tubes -- i just emailed and will call them tomorrow |
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Posted: 2/4/2013 10:32:22 PM EDT
[#25]
Quoted:
Those long tubes work if you put between 2 and 4 quarters in the bottom of the tube or cut 1/4 inch off of the threads. 3 quarters seems to be the perfect fit -- lol -- although im not going that route hopefully they will just replace the tubes if not then will have to cut them down -- just wouldnt trust the spacer / quarter deal |
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Posted: 2/4/2013 10:35:14 PM EDT
[#26]
Quoted:
the buffer is 3.25 but the internal measurement is 7.25 so there that might be what did it question is that buffer tube the one that came on the new frontier or one you put on? also if you put it on where did you get it? |
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Posted: 2/4/2013 10:42:24 PM EDT
[#27]
Well,
Not saying I know everything here... But, your bolt carrier shouldn't slam into the back of your receiver either... Pull trigger..bullet travels down the barrel... Get bast the gas port...some gas is sent down the tube... Gas hits the gas key and starts rearward travel of the bcg... Then bcg/buffer should slow down and not quite bottom out in the buffer tube... The last part is my concern...if your relying on the little bumper getting slammed into the back of the tube...something is going to fail at some point... My advice is look at the gas port size...if its out of spec send it back... Other option it to start with trying heavy buffers... Heavy buffers are used in the .mil as well...this is a running thing... I got my ass schooled on this a year or two ago... Put in an h buffer... 1 round in mag... Fire, if it locked back now install an h2 Repeat until you bcg won't lock back...then decrease one down on your heavy buffer... Then you will have a proper amount of mass to absorb the recoil...and more mass to lock bolt up again... Oh, another benefit is less recoil felt by the shooter... My suggestion... Bret |
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Posted: 2/4/2013 10:49:57 PM EDT
[#28]
That's a nice thought and at the range you can tinker around with that shit all you like but every time you change from light to heavy loads or from range ammo to defense ammo or change out a worn spring you are going to be creating a situation where your rifle will become unreliable. A carbine length gas system should have an "H" buffer and no further tinkering should be necessary.
Gas port size? Jesus we aren't building a piano here. These things have been running for more than 50 years with tried and true parts. My suggestion would be to splurge a little and buy quality true mill spec parts from tier one manufacturers.
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Posted: 2/4/2013 11:08:18 PM EDT
[#29]
Quoted:
That's a nice thought and at the range you can tinker around with that shit all you like but every time you change from light to heavy loads or from range ammo to defense ammo or change out a worn spring you are going to be creating a situation where your rifle will become unreliable. A carbine length gas system should have an "H" buffer and no further tinkering should be necessary. Gas port size? Jesus we aren't building a piano here. These things have been running for more than 50 years with tried and true parts. My suggestion would be to splurge a little and buy quality true mill spec parts from tier one manufacturers. Well, First off didn't say anything about loads...only buffers...and yes anyone can do this...once done its done... I only shoot what I'm keeping in the rifle...not some wierd ammo... So, now on the gas port...yep had a couple gas ports way over size...it happens... Yes I understand you may only buy from tier one suppliers...but, it still remains that the op is asking for help, I don't feel that We should go beyond that... These days people are getting what they can get... Ok, back to the original poster... Try the heavy buffer shuffle,,,bump up the buffer till it won't hold open afte a round then back it down one buffer size... Now, if you don't have other buffers available...we if there is someone in your area that may have a few and test them out and order the proper one... Carbine should be running a h buffer at least, but this build may require a h2 or 3 Bret |
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Posted: 2/4/2013 11:37:03 PM EDT
[#30]
after a little more looking at springs and buffers -- i find i have two different buffers and springs -- one buffer weights 84grams and the other 80grams -- one spring is 10.5" long and one is 11" long -- now the main problem is im not sure which buffer went with which spring -- lol -- is 4 grams enough weight to make a difference on that -- none are marked anywhere on them
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Posted: 2/4/2013 11:45:49 PM EDT
[#31]
No. 4 grams and 1/2 inch of spring will make no difference. Again, not a piano.
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Posted: 2/4/2013 11:51:45 PM EDT
[#32]
Quoted:
No. 4 grams and 1/2 inch of spring will make no difference. thanks didnt think it would but just wanted to make sure -- if i dont hear back from galati international by the time lpk's get here guess i will just trim off .25 on buffer tube -- the one stock that wont let the gas key hit lower is military spec 4 position -- the two 6 position that do let the gas key hit are commercial kits -- i put a quarter in each one and it stops the gas key from hitting -- not sure to just let quarter stay in each or trim -- lol --- also does those weights on the buffer sound good -- notice the h2 and higher weigh much more -- just almost sounds light weight really edited: never mind on buffer weight i see 3 oz is normal |
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Posted: 2/4/2013 11:52:20 PM EDT
[#33]
Quoted: Quoted: That's a nice thought and at the range you can tinker around with that shit all you like but every time you change from light to heavy loads or from range ammo to defense ammo or change out a worn spring you are going to be creating a situation where your rifle will become unreliable. A carbine length gas system should have an "H" buffer and no further tinkering should be necessary. Gas port size? Jesus we aren't building a piano here. These things have been running for more than 50 years with tried and true parts. My suggestion would be to splurge a little and buy quality true mill spec parts from tier one manufacturers. Well, First off didn't say anything about loads...only buffers...and yes anyone can do this...once done its done... I only shoot what I'm keeping in the rifle...not some wierd ammo... So, now on the gas port...yep had a couple gas ports way over size...it happens... Yes I understand you may only buy from tier one suppliers...but, it still remains that the op is asking for help, I don't feel that We should go beyond that... These days people are getting what they can get... Ok, back to the original poster... Try the heavy buffer shuffle,,,bump up the buffer till it won't hold open afte a round then back it down one buffer size... Now, if you don't have other buffers available...we if there is someone in your area that may have a few and test them out and order the proper one... Carbine should be running a h buffer at least, but this build may require a h2 or 3 Bret Yes, the op is asking for help and you are muddying the water with a bunch of nonsensical minutiae. You are asking him to buy a $100 worth of buffers and play around with them. His buffer tube is too long and for the cost of three quarters to put in the bottom of the buffer tube his problem will be adequately fixed. |
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Posted: 2/5/2013 12:01:03 AM EDT
[#34]
Quoted:
Quoted:
Quoted:
That's a nice thought and at the range you can tinker around with that shit all you like but every time you change from light to heavy loads or from range ammo to defense ammo or change out a worn spring you are going to be creating a situation where your rifle will become unreliable. A carbine length gas system should have an "H" buffer and no further tinkering should be necessary. Gas port size? Jesus we aren't building a piano here. These things have been running for more than 50 years with tried and true parts. My suggestion would be to splurge a little and buy quality true mill spec parts from tier one manufacturers. Well, First off didn't say anything about loads...only buffers...and yes anyone can do this...once done its done... I only shoot what I'm keeping in the rifle...not some wierd ammo... So, now on the gas port...yep had a couple gas ports way over size...it happens... Yes I understand you may only buy from tier one suppliers...but, it still remains that the op is asking for help, I don't feel that We should go beyond that... These days people are getting what they can get... Ok, back to the original poster... Try the heavy buffer shuffle,,,bump up the buffer till it won't hold open afte a round then back it down one buffer size... Now, if you don't have other buffers available...we if there is someone in your area that may have a few and test them out and order the proper one... Carbine should be running a h buffer at least, but this build may require a h2 or 3 Bret Yes, the op is asking for help and you are muddying the water with a bunch of nonsensical minutiae. You are asking him to buy a $100 worth of buffers and play around with them. His buffer tube is too long and for the cost of three quarters to put in the bottom of the buffer tube his problem will be adequately fixed. yea sorry the op had issue but might of saved me from having the same while we figured his out -- what is (if there is one) best space to have between gas key and lower -- i can put 1 quarter in and the gas key stops around 1/8" from the lower (mine must just barely be touching the lower without it) -- but also notice its sort of contoured in the bottom where the buffer hits it -- so guess im asking should i go with the width of 2 or is that space with 1 enough |
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Posted: 2/5/2013 5:34:37 AM EDT
[#35]
Correct me if I am wrong, but dont NF lowers have a warning in the box that says to use ONLY milspec buffer tubes and buttstocks on their lowers?
I know ATI does and it says the use of commercial buffers and buttstocks will cause catostrophic failure |
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Posted: 2/5/2013 5:43:50 AM EDT
[#36]
I took some pictures of the warnings in the box.
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Posted: 2/5/2013 6:38:09 AM EDT
[#37]
Quoted:
Then bcg/buffer should slow down and not quite bottom out in the buffer tube... Negative. It does and will every time. |
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Posted: 2/5/2013 8:25:07 AM EDT
[#38]
Quoted:
Quoted:
Then bcg/buffer should slow down and not quite bottom out in the buffer tube... Negative. It does and will every time. I think I may have found an answer to the problem. I also have a commercial buffer assembly. My first AR is a Bushy Carbon 15 with a commercial tube, I installed a Magpul ACS stock on it but now I am selling the Bushy. I want to use the commercial ACS stock on my new build. The commercial tube I bought to do this is from Omega Tacticle, they are CNC machined not extruded is why I chose it. After seeing this problem I contacted Omega Tacticle to see if this issue has ever came up with their tubes. This was their response to the tube length question: " For milspec its 7 inches but for commercial its 7.250 inches. It sounds like the spring may be wrong, where on the commercial tube the spring is longer not allowing it to contact the end of the tube. Where it works a bit diffrently than a milspec tube where the buffer hits the back, the commercial does not but it does reach the end of the compression spring. What I can do is send you the correct spring in case you accidently got the milspec spring that is shorter. Garth - OMEGA TACTICAL" It seems your issue could be a milspec spring in a commercial tube. The moral of this story may be to only use milspec buffer tube assemblys in Polymer lowers. |
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Posted: 2/5/2013 8:49:30 AM EDT
[#39]
Quoted:
Quoted:
Quoted:
Then bcg/buffer should slow down and not quite bottom out in the buffer tube... Negative. It does and will every time. I think I may have found an answer to the problem. I also have a commercial buffer assembly. My first AR is a Bushy Carbon 15 with a commercial tube, I installed a Magpul ACS stock on it but now I am selling the Bushy. I want to use the commercial ACS stock on my new build. The commercial tube I bought to do this is from Omega Tacticle, they are CNC machined not extruded is why I chose it. After seeing this problem I contacted Omega Tacticle to see if this issue has ever came up with their tubes. This was their response to the tube length question: " For milspec its 7 inches but for commercial its 7.250 inches. It sounds like the spring may be wrong, where on the commercial tube the spring is longer not allowing it to contact the end of the tube. Where it works a bit diffrently than a milspec tube where the buffer hits the back, the commercial does not but it does reach the end of the compression spring. What I can do is send you the correct spring in case you accidently got the milspec spring that is shorter. Garth - OMEGA TACTICAL" It seems your issue could be a milspec spring in a commercial tube. The moral of this story may be to only use milspec buffer tube assemblys in Polymer lowers. This guy from Omega Tacticle has already sent out a new spring to me just to make sure I have the correct one. 3 hours after I first contacted him. Big props to this guy! |
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Posted: 2/5/2013 8:54:11 AM EDT
[#40]
I wonder why some POLYMER lowers break??
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Posted: 2/5/2013 9:51:00 AM EDT
[#41]
I've never heard of 2 different springs for carbine tubes.
1 size buffer 1 size spring Sounds like someone is feeding you a BS excuse for out-of-spec items 
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Posted: 2/5/2013 10:11:55 AM EDT
[#42]
Two different springs? That is ridiculous. Certainly, there are springs that are different lengths. Used springs are shorter than new. High quality springs are generally longer than out of spec junk, but commercial vs. mil-spec. Preposterous. Buy quality parts. Buy a Wolf spring, ensure that your buffer is 3.25 inches long and if your tube happens to be 7.25 inches long then drop 3 U.S. quarters into it and drive on.
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Posted: 2/5/2013 10:28:06 AM EDT
[#43]
Either this guy "Garth" is easily confused,or has no idea WTF he is talking about
Get a refund from "Garth" for the crappy parts,and buy from a vendor that offers quality stuff. |
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Posted: 2/5/2013 11:11:23 AM EDT
[#44]
I'm curious to see if the "longer" spring makes a difference. I guess when just taking Garth at his word, there seems to be some logic behind his explanation.
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Posted: 2/5/2013 11:28:04 AM EDT
[#45]
Quoted:
I'm curious to see if the "longer" spring makes a difference. I guess when just taking Garth at his word, there seems to be some logic behind his explanation. Thats what I thought until I read what these other guys are saying and thought it out. If the front rim of the buffer is supposed to bottom out against the compressed spring in a commercial buffer assembly. That would be a solid metal to metal stop. I doubt this is the design. The end of a buffer is designed to hit the end of the tube with a rubber stop, not a solid metal to metal contact that a fully compressed spring would be. Garths explaination would result in a very harsh action in my opinion. I agree with these guys calling BS Is the buffer actually supposed to hit the end of the buffer tube with each cycle? Or is the correct bolt weight, correct dwell, correct buffer weight, correct spring tension supposed to keep the action cycling back far enough to catch the bolt open after the last round is fired. While cycling smoothly and not bottoming out in the tube?? |
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Posted: 2/5/2013 11:49:31 AM EDT
[#46]
The buffer will contact the end of the tube every time the gun is fired.
How hard it makes contact depends on the strength/age of the spring. If your tube is too long,the buffer/BCG will overtravel too deep into the tube,causing the BCG to slam into the lower receiver just like the photos. |
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Posted: 2/5/2013 12:01:37 PM EDT
[#47]
Omega Tactical sells China made stuff on ebay. The springs the include are a little short and buffers are way under weight. These stock sets are also sold on Sportsmans Guide. You need a longer spring and a heavier buffer. Also the threads on there tubes are not always cut to the right depth.
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Posted: 2/5/2013 12:16:14 PM EDT
[#48]
Different length springs?? Uh, no..
Quarters in a buffer tube?? Uh, no.. We are just seeing the beginning of a virtual tsunami of fucked up frankenbuilds cobbled together with subpar parts. Buy a real lower and a mil-spec tube from a known quality vendor and be done with it. Posted Via AR15.Com Mobile |
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Posted: 2/5/2013 12:21:56 PM EDT
[#49]
Quoted: Different length springs?? Uh, no.. Quarters in a buffer tube?? Uh, no.. We are just seeing the beginning of a virtual tsunami of fucked up frankenbuilds cobbled together with subpar parts. Buy a real lower and a mil-spec tube from a known quality vendor and be done with it. Posted Via AR15.Com Mobile Exactly. If, however, you are stuck with an out of spec tube or can't afford $100 for a new Colt tube the quarter trick works and will at least prevent damage to a lower receiver. This trick has been done for years in 9mm AR's to get them to run right. It won't hurt a thing. |
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Posted: 2/5/2013 12:28:58 PM EDT
[#50]
Quoted:
Omega Tactical sells China made stuff on ebay. The springs the include are a little short and buffers are way under weight. These stock sets are also sold on Sportsmans Guide. You need a longer spring and a heavier buffer. Also the threads on there tubes are not always cut to the right depth. You do not need a longer spring,or a heavier buffer.There is no such thing as a longer carbine spring,and a std buffer will work fine. Your main problem seems to be the tube,and replacing that shitty,Chinese spring and buffer with quality stuff would be a wise decision also. Just order carbine parts from a dealer that sells in-spec merchandise,and all the issues in this thread will disappear. PK Firearms,BCM,and other trusted vendors come to mind when looking for the right stuff
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