If he has the new barrel installed correctly, and the factory set fsb and barrel are out of alignment he would simply need to send the product back to JSE for repair or replacement... or the shop who did the install could resolve the issue with a slight tuning. I have installed quite a few barrels and gas blocks and have never had one need repair or replacement, the most I have had to do is stake the set screws on a gas block (steel). As stated, I have built my fair share of these weapons and have never seen one that cost as little as 180 dollars, buying a new barrel and buffer is in no way comparable to buying a new rifle. The reason I suggested buying a new barrel simply stems from the fact that if the barrel he currently has is used and has been turned down to a smaller outside diameter, perhaps a new barrel is in order, worst case scenario he ends up with a brand new barrel that has no unsightly machine/ thread marks that comes from a reputable supplier with customer service and a return policy. Again not trying to start a pissing match, just offering my own personnel opinion.
ar problems
- Thread starter 4x4demon
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I loosened and tightened the castle nut with a punch and light hammer taps, receiver was held in place in a vice with padding. No dents were apparent and the nut turned easily over the thread. No scuff marks at any time from memory. No idea on buffer markings, its the same one that came from you. Receivers fit tight, Eveything returned to original position. Working the action is smooth and effortless. Different mags, same issue no matter how many rounds are in it. Will inspect tonight. At first it was a light coating of lube, then it was dripping wet. This was the only time it worked.
nineteenhundred
Well-Known Member
Ok..good.
That lower was never fired until you fired it. I am not sure which buffer Plum Crazy uses. If it all looks ok, we'll trust it.
Ok, the next new thing is the BCG. Without me seeing it and it being brand new it may take a few rounds for the bolt to 'team up' with the barrel group. It might not hurt to verify the headspace if you can.
If you put the FSB back on like I had it,then the gas block IS aligned correctly. Don't worry about it, no matter what everyone else thinks it looks like. You can ream and put in taper pins if you want, you know it is tight.
If you keep it, lube it up good and shoot a couple or three more boxes and see if it settles in. If it continues to beat up the brass you may need a heavier buffer.
Thats my best advice without looking at it myself.
That lower was never fired until you fired it. I am not sure which buffer Plum Crazy uses. If it all looks ok, we'll trust it.
Ok, the next new thing is the BCG. Without me seeing it and it being brand new it may take a few rounds for the bolt to 'team up' with the barrel group. It might not hurt to verify the headspace if you can.
If you put the FSB back on like I had it,then the gas block IS aligned correctly. Don't worry about it, no matter what everyone else thinks it looks like. You can ream and put in taper pins if you want, you know it is tight.
If you keep it, lube it up good and shoot a couple or three more boxes and see if it settles in. If it continues to beat up the brass you may need a heavier buffer.
Thats my best advice without looking at it myself.
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SpeedRacer
Well-Known Member
Upper, lower, BCG. Find a spare of each and swap them out one at a time. You'll figure out where the problem is real quick.
My money is still on the gas system. Even if screws "work" for the FSB, the simple fact that that step was half assed makes me assume anything else done to the barrel/gas system was as well.
My money is still on the gas system. Even if screws "work" for the FSB, the simple fact that that step was half assed makes me assume anything else done to the barrel/gas system was as well.
nineteenhundred
Well-Known Member
I did the 'work'. It is not half-assed. The screws have nothing to do with the gas system operation. That gas block is perfectly aligned and tighter than spec on the journal. I turned the barrel down to remove the gouges the previous owner put in it removing the FSB. Anyone who has ever removed a FSB from a S&W barrel knows how hard that can be. There are some chatter marks, but 4x4 saw all this when he bought it. I hid nothing from him. This was intended as my truck/beater/loaner so I didn't care what it looked like. It worked perfectly for me with my lower and BCG. He is using it with a new lower and BCG, that is what changed. He saw it, he liked it, he bought it. You people made him begin to question his decision. I know he won't do it but I would buy the barrel and FSB back for what I paid for it.(that would be between me and him).
He wanted a rifle for as little as possible and I tried to help. If anyone has suggestions to help him get this one going, then help. If you think he should dump more money into it, then buy it from him and he can get a new rifle and you can put any money in it you want too. I don't want the lower or the upper, but I did like that barrel.
He wanted a rifle for as little as possible and I tried to help. If anyone has suggestions to help him get this one going, then help. If you think he should dump more money into it, then buy it from him and he can get a new rifle and you can put any money in it you want too. I don't want the lower or the upper, but I did like that barrel.
nineteenhundred
Well-Known Member
Ok...
does it look like the bolt catch is rubbing on it all the time or only when the magazine raises it? It should only touch when the empty magazines follower raises it up.
or is it the hammer rubbing it?
remind me...aren't the FCG parts in that lower made of polymer? How much rubbing is evident? Are the polymer parts showing wear?
can you take some pics of the wear on the BC.
another test you can try is as follows:
remove the magazine and make sure the rifle is unloaded.
seperate the upper and lower.
make sure the BCG is lubed like you fire it.
with the BCG in battery tilt the muzzle upwards
does the BCG disengage the barrel extension under its own weight.
it should not. if it does the gas rings may need replacing. since it is new this should not be the case, but its worth checking anyway.
does it look like the bolt catch is rubbing on it all the time or only when the magazine raises it? It should only touch when the empty magazines follower raises it up.
or is it the hammer rubbing it?
remind me...aren't the FCG parts in that lower made of polymer? How much rubbing is evident? Are the polymer parts showing wear?
can you take some pics of the wear on the BC.
another test you can try is as follows:
remove the magazine and make sure the rifle is unloaded.
seperate the upper and lower.
make sure the BCG is lubed like you fire it.
with the BCG in battery tilt the muzzle upwards
does the BCG disengage the barrel extension under its own weight.
it should not. if it does the gas rings may need replacing. since it is new this should not be the case, but its worth checking anyway.
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SpeedRacer
Well-Known Member
That's what I'm trying to do. I personally think it's a problem with the gas system. I personally think it looks half-assed. That's my opinion, that's me trying to help.
Regardless what's wrong with it, none of this iDiagnosis is going to help. Spending hours dicking around with it based on internet advice is probably only going to make it worse.
Take it to the range. Borrow a known functional complete AR from someone. Using FULL POWER ammo:
Shoot your rifle. Does it work?
Put the other BCG in your rifle. Does it work? If so, your BCG is bad. If not...
Put your upper on the other lower. Does it work? If so, your lower is bad. If not...
Put your lower and BCG on the other upper. Does it work? If so, your upper is bad.
It's not rocket surgery. At least narrow down which half of the rifle is the problem and go from there.
I just installed a gas block (set scew low profile) for the 1st time. To clear the free float tube I had to remove the front handguard reatiner (sits right behind the gas block). After sliding the gas block on and eyeballing it straight I tried to figure out a way to check gas port alignment.
Take your pinky and stick it in the chamber (upper off the lower makes this easy) and then blow into the muzzle end with your mouth (aksk your GF, she will have more practive with this technique, hopefully)
You should be able to hear air coming out of the gas tube, I left the gas block slightly loose and tuned it slightly back and forth till I could hear the most air passing thru. I did this with the gas tube installed and with just the gas block mounted. The tube sure does cut down on flow, at least with lung pressure.
I still think it is the bcg. Have you had it all the way apart and cleaned the mess out ofit, and then made sure the gas ring slots are all not in line? Pressure goes all the way into the carrier and act on the bolt itself. Make sure there are no obstructions in the gas key, maybe some left over metal from machining?
The fact it works a few times, then stops tells me you may have some dirt banging around in the bcg.
Take your pinky and stick it in the chamber (upper off the lower makes this easy) and then blow into the muzzle end with your mouth (aksk your GF, she will have more practive with this technique, hopefully)
You should be able to hear air coming out of the gas tube, I left the gas block slightly loose and tuned it slightly back and forth till I could hear the most air passing thru. I did this with the gas tube installed and with just the gas block mounted. The tube sure does cut down on flow, at least with lung pressure.
I still think it is the bcg. Have you had it all the way apart and cleaned the mess out ofit, and then made sure the gas ring slots are all not in line? Pressure goes all the way into the carrier and act on the bolt itself. Make sure there are no obstructions in the gas key, maybe some left over metal from machining?
The fact it works a few times, then stops tells me you may have some dirt banging around in the bcg.
I'm not sure that the bcg is rubbing on the bolt catch becuase it doesn't show any wear on it, and it is polymer. I should've gotten some pics. It's not much wear at all, its just light drag marks. I've had the upper off with the bcg in it and turned it every which way and it didnt not come loose. I have not taken the bcg apart, I oiled it and lubed it when I bought it.
I tried the air pressure test before with an empty shell and an air compressor. There was flow but it was weaker than the nozzle pressure but I cant gurrantee a complete seal on the muzzle.
I thought all m4/ar15s used basically the same bcg? Is it possible that there are different types and I bought the wrong one?
This is the bcg I bought.
http://www.dsarms.com/ZM4_AR15-Semi-Auto-Complete-Bolt-Group-Assembly---ZM485018509-A/productinfo/ZM485018509-A/
I tried the air pressure test before with an empty shell and an air compressor. There was flow but it was weaker than the nozzle pressure but I cant gurrantee a complete seal on the muzzle.
I thought all m4/ar15s used basically the same bcg? Is it possible that there are different types and I bought the wrong one?
This is the bcg I bought.
http://www.dsarms.com/ZM4_AR15-Semi-Auto-Complete-Bolt-Group-Assembly---ZM485018509-A/productinfo/ZM485018509-A/
nineteenhundred
Well-Known Member
The air test is really only good to let you know that the gas port is in line with the FSB gas port. The volume of flow through the little port will never be equal to your air compressor flow, and your air compressor pressure will never start to come near the pressure of gas through the port from a fired shell.
Your BCG is a semiauto configured BCG. It has a carrier that is shaped a little different from a full auto BC and is a little lighter. It has the same bolt in both. It might be good for you to disassemble the bolt from the carrier and check it out for anything obvious. There are instruction to help you do this on the web.
It is imperative that you find out what is causing the scuff marks on your BC . It may be nothing. Check the inside if the buffer tube for scuffing too.
We may be getting somewhere after all.
Interchanging parts may not prove anything. Just because it works in one rifle doesn't guarantee it to work in another. If you try it, exchange the lower and BCG at the same time between rifles first. Try both rifles. If it works, then try the single combinations of parts between rifles.
Your BCG is a semiauto configured BCG. It has a carrier that is shaped a little different from a full auto BC and is a little lighter. It has the same bolt in both. It might be good for you to disassemble the bolt from the carrier and check it out for anything obvious. There are instruction to help you do this on the web.
It is imperative that you find out what is causing the scuff marks on your BC . It may be nothing. Check the inside if the buffer tube for scuffing too.
We may be getting somewhere after all.
Interchanging parts may not prove anything. Just because it works in one rifle doesn't guarantee it to work in another. If you try it, exchange the lower and BCG at the same time between rifles first. Try both rifles. If it works, then try the single combinations of parts between rifles.
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nineteenhundred
Well-Known Member
You are not helping....
The 'gas system' consists of more than the bolts holding the FSB on. You need to get over it.
You just like to talk sh*** to hear yourself I think. this is my last response to you VD
Some of you are locked in on the 'gas system'. You do realize that the GS consists of the barrel gas port size, FSB port, gas tube, bolt key, bolt, gas rings, etc. Any fault in any of these can cause trouble. Then there is the recoil system and the feeding system, and the firing system, ammo, lubrication, etc.
The upper on this rifle is the ONLY thing on it that I KNOW had WORKED because I used it on MY lower with NO malfunctions.
His lower was unfired brand new. His bolt was unfired brand new. It may simply need lubbing and firing.
I think you actually don't like the FSB, particuarly the offending screws. The way the FSB is secured has absolutly nothing to do with the operation of the gas system. You will see them from vendors with set screws from both sides where I have bolts. Would you trust that more? Some even supply roll pins instead of taper pins. Some only set screw from the bottom in dimples. The whole purpose is to keep the FSB secure.
Just because you don't like the way it looks doesn't make it bad.
The 'gas system' consists of more than the bolts holding the FSB on. You need to get over it.
You just like to talk sh*** to hear yourself I think. this is my last response to you VD
Some of you are locked in on the 'gas system'. You do realize that the GS consists of the barrel gas port size, FSB port, gas tube, bolt key, bolt, gas rings, etc. Any fault in any of these can cause trouble. Then there is the recoil system and the feeding system, and the firing system, ammo, lubrication, etc.
The upper on this rifle is the ONLY thing on it that I KNOW had WORKED because I used it on MY lower with NO malfunctions.
His lower was unfired brand new. His bolt was unfired brand new. It may simply need lubbing and firing.
I think you actually don't like the FSB, particuarly the offending screws. The way the FSB is secured has absolutly nothing to do with the operation of the gas system. You will see them from vendors with set screws from both sides where I have bolts. Would you trust that more? Some even supply roll pins instead of taper pins. Some only set screw from the bottom in dimples. The whole purpose is to keep the FSB secure.
Just because you don't like the way it looks doesn't make it bad.
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SpeedRacer
Well-Known Member
My point, and I believe his point, is that you can't rule out the gas system. It's pretty obvious you're trying to blame everything BUT the gas system (the part you messed with). It's in 4x4's best interest that he receive opinions from more than just you.
And you didn't just swap the FSB for screws. You admittedly did a lot more work than that to it, all which has a lot of potential for error. Regardless, you have no reason to be defensive about it if the end goal really is getting the rifle running.
nineteenhundred
Well-Known Member
Once again, That was a S&W barrel that I bought from a member here. He had gouged it removing the FSB. It would never again work for a .750 FSB. I turned it down to .625 and put that type FSB on it. It is very tight. I did not alter the FSB in any way. I turned the M4 profile off the barrel. It is still larger than a pencil diameter barrel. There are a few chatter marks from the lathe but I did not want to turn the barrel any smaller as I didn't care what it looked like. It was never intended to be a showpiece.
The FSB has the proper handguard ring for spacing and is aligned straight up. With the large port in the FSB you would be supprised at the amount of visible tilt you can have in a FSB and it funciton fine. I had no taper pins so I threaded the new hole I drilled and threaded them, then put in the bolts.
All of this was explained when he bought it.
I am perfectly willing to accept fault if it is mine, but I actually used this upper, so I know it runs. The parts I 'messed' with are the only proven parts on the rifle.
I already said that I would buy the barrel back.
The FSB has the proper handguard ring for spacing and is aligned straight up. With the large port in the FSB you would be supprised at the amount of visible tilt you can have in a FSB and it funciton fine. I had no taper pins so I threaded the new hole I drilled and threaded them, then put in the bolts.
All of this was explained when he bought it.
I am perfectly willing to accept fault if it is mine, but I actually used this upper, so I know it runs. The parts I 'messed' with are the only proven parts on the rifle.
I already said that I would buy the barrel back.
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