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Posted: 1/26/2015 9:19:19 PM EDT
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Ok, so far every 7.62x39 bolt that I've purchased has had the same issue where the extractor is too strong for the ejector to push the spent case out of the chamber. This results in stovepipes and other instances where the case is just pushed on a 45 degree angle and it rams into the wall of the ejection port.
Just got a tactical ambush bcg and it's ran better than the others I've tried but still stovepipes. Hit up Liberty Gun Works to try out their bolt as well. Am I the only one with this issue, and does anyone have any suggestions? Sorry if this thread sucks I'm new here, been stalking ar15.com for a while and finally decided to make a profile. |
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Welcome, can't help you my TA bolt works like any other bolt.
If you are having the same issue with different bolts makes me think to look elsewhere like a sticky chamber maybe? When it does eject how far is it throwing brass? If it is barely clearing the chamber I would look at the gas as suggested above. |
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I was thinking the same...a buffer or gas issue.
Mine would often not hold open on the last shot (the only problem I have had) and reducing the gas via an adjustable gas block helped slow the bolt enough that its as reliable as any standard 5.56 AR...shoots smooth too. The OP's issue could be too little gas, just a thought. |
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Ok, so far every 7.62x39 bolt that I've purchased has had the same issue where the extractor is too strong for the ejector to push the spent case out of the chamber. This results in stovepipes and other instances where the case is just pushed on a 45 degree angle and it rams into the wall of the ejection port. Just got a tactical ambush bcg and it's ran better than the others I've tried but still stovepipes. Hit up Liberty Gun Works to try out their bolt as well. Am I the only one with this issue, and does anyone have any suggestions? Sorry if this thread sucks I'm new here, been stalking ar15.com for a while and finally decided to make a profile. If you've tried multiple bolts with the same problem, I don't think the bolt is the issue. I would assume that you're using steel cased ammo since its 7.62x39 and I would guess that you proably have to tight of a chamber in the barrel which is causing the cheap steel cased ammo to stick when it expands. Just my 2 cents. |
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The bolt always holds open on the last round and always picks up a second round but doesn't always push the first spent round out of the chamber causing a stove pipe.
I actually bought an adjustable gas block because I saw on another .308 thread that someone was always having stove pipes with their ar10 and someone suggested that it was way over gassed. But it wasn't until I started putting a spent round in the chamber and pulling back on the charging handle that I realized that the issue is bolt related because half the time the extractor would hold onto the spent case with a death grip. The rest of the time the spent case would flop out and when messing around switching extractors from one bolt to another I got one spent case to eject correctly. At the range it's the same issue. The rounds either barely flop out, some get properly ejected and the rest get shoved into the wall of the ejection port or get shoved sideways causing a stovepipe. And as I mentioned before it always holds open on the last round so I know it's not a gas issue. Once I realized that it wasn't over gassed I threw the original gas block back on because I thought if it had a more violent action that it would help knock the spent cases out of the bolt face a little easier. |
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7.62x39 bolts for the AR15 are really not engineered well. The extractor location and lip geometry really pushes the engineer to use a deeper bolt face, so the extractor groove can be made larger for the thicker case rim.
A lot of people find a solution and the guns run, but in this case, I would have you look at your extractor lip corners. If they are sharp, it will death grip the case against the ejector tension and the limited groove depth of the extractors. If you tune the corners with a little bit of buffing, you can get rid of the impingement of the case rim between the extractor lip and ejector tension. Try that and see what happens. |
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There was an earlier thread on this forum about someone slightly modding their 7.62x39 ejector to fix an issue, if I remember correctly they rounded the edges of the face. Can't say for sure but they included some nice close up pics to display the mod.
As for building a piston upper to avoid corrosion, I personally don't see the point. If you're shooting corrosive you're gonna have to clean after every trip. Both my 7.62x39 and 5.45x39 DI ARs shoot corrosive exclusively and they are rust free after years of shooting. |
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http://i113.photobucket.com/albums/n221/kronickilla06/IMG_0019_zps7ea4c344.jpg Funny you say that because all of my brass has two lines from the edges of the extractor. I'll try that, I've been thinking of getting some polishing compound for my feed ramps so I guess I can buff the extractor a bit as well. Hi, I took a look at your photo and noticed that your brass has horizontal lines on it indicating tool marks from when it it was reamed. A rough chamber is going to goof up you timing, cause ejection problems, and because the extractor works harder really leave those pronounced marks. It's my observation that parkerized barrels are more prone to have problems with this as chromed and Melonited chambers are "slicker" and it's easier for the AR to extract from them. A rough chamber will also mimick undergassing too. Best Wishes: |
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There was an earlier thread on this forum about someone slightly modding their 7.62x39 ejector to fix an issue, if I remember correctly they rounded the edges of the face. Can't say for sure but they included some nice close up pics to display the mod. This should be a standard feature on any Russian short parent cartridge chambering in the AR15. I do it on the 6.5 Grendel, and I just don't have any functioning issues with my guns. 
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I use the Brownell's bolt disassembly tool, chuck the ejector up in a drill, and radius it on a steel file, then polish it, then Oxpho-blue it. I've done it on a lot of bolts now.
It's one of about 20 different tweaks you can do to a bolt assembly to get smoother feeding, extraction, ejection, reliability, pleasant treatment of brass, and accuracy. |
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I noticed the reloading stuff in the background of your pic. If I wanted to get into reloading, how much am I looking to spend? I'm thinking of reloading 5.56, possibly 7.62x39 as well as getting into 300AAC. Which I don't own yet because I don't reload. The reloading section here on the site is pretty good, with a lot of helpful information. I have a totally new reloading bench purpose-built. I have also co-authored 2 reloading handbooks, and put a lot of work into the last one that dealt specifically with reloading for the AR15 with a cartridge that descended from the 7.62x39, the 6.5 Grendel, so a lot of the considerations are the same. I also reload for 5.56, .270 Winchester, .260 Remington....several other rifle and pistol cartridges. Biggest thing with reloading is to have a competent mentor who has been reloading for a while, and use industry sources for procedures and data. The reloading section here on AR15.com has a lot of good info again. 
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I use the Brownell's bolt disassembly tool, chuck the ejector up in a drill, and radius it on a steel file, then polish it, then Oxpho-blue it. I've done it on a lot of bolts now. It's one of about 20 different tweaks you can do to a bolt assembly to get smoother feeding, extraction, ejection, reliability, pleasant treatment of brass, and accuracy. For a newb like me. Are there guides out there for bolt smoothing? Prefer pictures. I'm having a similar issue with an extractor death gripping the brass. |
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What issues are you having?
Also, I just spent like 3 hours swapping parts between two bolts, rounding the ejectors, trying with and without the o-ring gasket, etc. and still haven't found a cure. P.S. If you're going to take out your ejector you should have a specialty bolt holder for it otherwise you're going to have a bad time. I have the entry level Wheeler's armorer kit and the lower vise block has a piece that holds your bolt while you knock out the ejector pin. I would have been absolutely fucked without it. |
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What issues are you having? Also, I just spent like 3 hours swapping parts between two bolts, rounding the ejectors, trying with and without the o-ring gasket, etc. and still haven't found a cure. P.S. If you're going to take out your ejector you should have a specialty bolt holder for it otherwise you're going to have a bad time. I have the entry level Wheeler's armorer kit and the lower vise block has a piece that holds your bolt while you knock out the ejector pin. I would have been absolutely fucked without it. I tried searching for the thread I made describing this issue. It's just a death grip on the case.  " />
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I'm having the same issue. I'm also using the same Bulgarian ammo. (Arsenal right?) To everyone that's gonna say it's the ammo, I've also had the same malfunctions with PMC Bronze. Edit: I hope it's not the ammo, I bought a shit ton of it... This can often be solved by taking the sharp edges off the extractor lip, but it's also indicative of the failure of the industry to study basic firearms design, and try to wing it on the coat tails of good design work that went ahead of them on a totally different cartridge. The 5.56 bolt face is a bit shallow for 7.62x39 is the short answer. I basically laid it out in my posts above. Thick rim of the Russian short plus .124" bolt face depth is pushing things too tight for good articulation when feeding and extracting. My measured 7.62x39 case rims range from .055" to .057", whereas the 5.56 has a very thin .045" rim. Something has to be adjusted somewhere with the 7.62x39 either forward or backwards with the bolt face or extractor groove, and you don't want to move forward on the edge of the extractor because the lip will then becomes thinner and weaker. There are guys who make components for a living who will argue against this all day long, for the simple reason that they don't want to change the .124" bolt face depth. |
| I'm possibly going to take a dremel to the lip of my extractor today. My Liberty Gun Works bolt is coming in 3 weeks. I spoke with the guy at Liberty and he told me that his bolts would measure out of spec with head space gauges and would be a tad loose. So I'm thinking his bolts take the face of the bolt in a bit (as you've suggested should happen) so that should alleviate the issue as well. |
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I'm possibly going to take a dremel to the lip of my extractor today. My Liberty Gun Works bolt is coming in 3 weeks. I spoke with the guy at Liberty and he told me that his bolts would measure out of spec with head space gauges and would be a tad loose. So I'm thinking his bolts take the face of the bolt in a bit (as you've suggested should happen) so that should alleviate the issue as well. I left it be. I need to do it but I also went with the Cason bolt that works great. It is like giving up but it does work. |
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I'm possibly going to take a dremel to the lip of my extractor today. My Liberty Gun Works bolt is coming in 3 weeks. I spoke with the guy at Liberty and he told me that his bolts would measure out of spec with head space gauges and would be a tad loose. So I'm thinking his bolts take the face of the bolt in a bit (as you've suggested should happen) so that should alleviate the issue as well. Gas guns run better with .003" of slop, which is why many headspace gauges fail on the excessive length gauge. On a bolt gun, we don't need .003" of slop. When you tune the extractor, just use the cotton buffing wheel with some polish, or even toothpaste. Don't use a grinding or cutting wheel. Just carefully take the sharp edges off, and clean it up. You can also polish the front end of the extractor so that it will smoothly slip over the case head as the bolt goes into battery. 
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This can often be solved by taking the sharp edges off the extractor lip, but it's also indicative of the failure of the industry to study basic firearms design, and try to wing it on the coat tails of good design work that went ahead of them on a totally different cartridge. The 5.56 bolt face is a bit shallow for 7.62x39 is the short answer. I basically laid it out in my posts above. Thick rim of the Russian short plus .124" bolt face depth is pushing things too tight for good articulation when feeding and extracting. My measured 7.62x39 case rims range from .055" to .057", whereas the 5.56 has a very thin .045" rim. Something has to be adjusted somewhere with the 7.62x39 either forward or backwards with the bolt face or extractor groove, and you don't want to move forward on the edge of the extractor because the lip will then becomes thinner and weaker. There are guys who make components for a living who will argue against this all day long, for the simple reason that they don't want to change the .124" bolt face depth. Quoted:
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I'm having the same issue. I'm also using the same Bulgarian ammo. (Arsenal right?) To everyone that's gonna say it's the ammo, I've also had the same malfunctions with PMC Bronze. Edit: I hope it's not the ammo, I bought a shit ton of it... This can often be solved by taking the sharp edges off the extractor lip, but it's also indicative of the failure of the industry to study basic firearms design, and try to wing it on the coat tails of good design work that went ahead of them on a totally different cartridge. The 5.56 bolt face is a bit shallow for 7.62x39 is the short answer. I basically laid it out in my posts above. Thick rim of the Russian short plus .124" bolt face depth is pushing things too tight for good articulation when feeding and extracting. My measured 7.62x39 case rims range from .055" to .057", whereas the 5.56 has a very thin .045" rim. Something has to be adjusted somewhere with the 7.62x39 either forward or backwards with the bolt face or extractor groove, and you don't want to move forward on the edge of the extractor because the lip will then becomes thinner and weaker. There are guys who make components for a living who will argue against this all day long, for the simple reason that they don't want to change the .124" bolt face depth. Do you happen to build 7.62x39 uppers as a business? |
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Quoted: I noticed the reloading stuff in the background of your pic. If I wanted to get into reloading, how much am I looking to spend? I'm thinking of reloading 5.56, possibly 7.62x39 as well as getting into 300AAC. Which I don't own yet because I don't reload. First read this thread, http://www.ar15.com/forums/t_6_42/263380_Everything_You_Wanted_to_Know_About_Reloading_But_Was_Afraid_to_Ask.html Then go to the Reloading Forum, http://www.ar15.com/forums/f_6/42_Reloading.html&page=1 and read the tacked threads at the top of the page. Then post. |
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Do you happen to build 7.62x39 uppers as a business? No. If I was doing that, for me, the right answer would be to be able to control: * Barrel blank or contoured barrel source, using .311" grooves * Correct reamer for gas gun operation ( I would immediately call up my friends in Finland who made barrels for SAKO and pick their brains on reamer specs.) * Source specific barrel extensions to handle the larger case diameter-dimensions are the same, but tolerances have to be tighter * Source specific bolts made to work with 7.62x39, with a deeper bolt face and some other critical details (lug length, bolt OAL, pin protrusion, etc.) * Source specific carriers with the correct critical dimensions (vent hole locations, diameters, bore diameters, camming specs, dims uniformity, nitrided) It would take some RDT&E to do at a level that would satisfy me, but one of the biggest problems is the ammunition. It's just not consistent looking over the market, like everything else related to the AK. How do you port your barrels, buffer, and spring the gun if the ammo is all over the pressure curve? All these reasons and more make me cling to the 6.5 Grendel, which is what even the Russians wish 7.62x39 would have been. On top of that, we have a specific steel case load for the Grendel that was tweaked for 7 years until finalized, so affordable steel case ammo isn't much of an appeal for 7.62x39 AR's for me personally. As a customer, you really have to be selective and highly educated about what steps to follow when building and maintaining a 7.62x39 AR, ranging from modifying the feed ramps, to magazines, gas system, chamber, researching the vendors and where they get their bolts, and keeping tight controls on what ammo you buy. Even then, a lot of people end up with non-functioning guns, and the ammo situation chokes some of the best guns on the market. |
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No issues with 16 inch barrel, semi auto with brass ammo. I want it to work in full auto, short barrel with steel cased. Quoted:
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So your cason bolt works great without this issue? If so than I'm excited to get my new bolt in the mail. No issues with 16 inch barrel, semi auto with brass ammo. I want it to work in full auto, short barrel with steel cased. That's really the allure for people in the NFA crowd, because you can buy steel cased ammo affordably, and the guns command more authority with the muzzle blast versus 5.56 if burning ammo for fun. |
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Gas guns run better with .003" of slop, which is why many headspace gauges fail on the excessive length gauge. On a bolt gun, we don't need .003" of slop.
When you tune the extractor, just use the cotton buffing wheel with some polish, or even toothpaste. Don't use a grinding or cutting wheel. Just carefully take the sharp edges off, and clean it up. You can also polish the front end of the extractor so that it will smoothly slip over the case head as the bolt goes into battery. So I started buffing the rim and outside of the extractor. This didn't work. Then I took a carbide dremel bit to the rim of the extractor and beveled the rim. Still no luck. I took a bit of material out of the notch in the ejector to allow it to stick out a bit more. Still nothing. The good news is there is less death grippage happening but now the empty casings just kinda flop off the face of the bolt. I did get one shell to eject properly but when I checked that it the rim of the case looked like a dime because of how many times I've chambered it in and tried to eject it. The entire scenario perplexes me so I'm going to wait for my new bolt to come in the mail and update the thread. Also, thanks for your help and sorry for being annoying I just wanted to document the entire ordeal so it can possibly help someone else out. |
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So I started buffing the rim and outside of the extractor. This didn't work. Then I took a carbide dremel bit to the rim of the extractor and beveled the rim. Still no luck. I took a bit of material out of the notch in the ejector to allow it to stick out a bit more. Still nothing. The good news is there is less death grippage happening but now the empty casings just kinda flop off the face of the bolt. I did get one shell to eject properly but when I checked that it the rim of the case looked like a dime because of how many times I've chambered it in and tried to eject it. The entire scenario perplexes me so I'm going to wait for my new bolt to come in the mail and update the thread. Also, thanks for your help and sorry for being annoying I just wanted to document the entire ordeal so it can possibly help someone else out. Quoted:
Gas guns run better with .003" of slop, which is why many headspace gauges fail on the excessive length gauge. On a bolt gun, we don't need .003" of slop.
When you tune the extractor, just use the cotton buffing wheel with some polish, or even toothpaste. Don't use a grinding or cutting wheel. Just carefully take the sharp edges off, and clean it up. You can also polish the front end of the extractor so that it will smoothly slip over the case head as the bolt goes into battery. So I started buffing the rim and outside of the extractor. This didn't work. Then I took a carbide dremel bit to the rim of the extractor and beveled the rim. Still no luck. I took a bit of material out of the notch in the ejector to allow it to stick out a bit more. Still nothing. The good news is there is less death grippage happening but now the empty casings just kinda flop off the face of the bolt. I did get one shell to eject properly but when I checked that it the rim of the case looked like a dime because of how many times I've chambered it in and tried to eject it. The entire scenario perplexes me so I'm going to wait for my new bolt to come in the mail and update the thread. Also, thanks for your help and sorry for being annoying I just wanted to document the entire ordeal so it can possibly help someone else out. The ejector protrudes enough already as is. You might have made things worse by allowing more forward protrusion with the ejector. Use new brass for function testing, because a damaged case rim will bind against the inside walls of the bolt face. |
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The ejector protrudes enough already as is. You might have made things worse by allowing more forward protrusion with the ejector.
Use new brass for function testing, because a damaged case rim will bind against the inside walls of the bolt face. Towards the end of my experience going full retard I ended up switching the ejector with the one from my other 7.62x39 bolt. I don't really think that I changed the dimensions of that ejector very much I mostly just took off a bit of the finish. And yeah you're right, I'll leave the function testing to the range because this shit is driving me crazy. |
| I cannot recommend Cason Engineering's bolt highly enough. Absolutely zero issues with it. Made my AR-47 experience a true delight. I tweaked the buffer weight just to get the ejection angle juuuuust right. But other than that and some magazine trial and error, my rifle runs flawless with it. |
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I cannot recommend Cason Engineering's bolt highly enough. Absolutely zero issues with it. Made my AR-47 experience a true delight. I tweaked the buffer weight just to get the ejection angle juuuuust right. But other than that and some magazine trial and error, my rifle runs flawless with it. Carbine gas I assume. What barrel length and buffer weight? |
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