AR Sponsor
Posted: 12/19/2004 1:57:42 PM EDT
|
I built (mostly just put together) my first ever AR and now I'm having troubles. I bought the lower complete, the upper semi-complete with a bolt carrier and charging handle from reputable dealers here on AR15.com. All of these parts are RRA parts. I then bought a complete 14.5" M4, chrome-lined barrel from Gunsmoke Enterprises. I perm. attached a Phantom 5C2 and installed the barrel onto the upper. All of this went just fine. I went out yesterday to shoot it and had an extraction problem. It would not extract the fired round. The case rims were being ripped off by the extractor. I had to tap the spent cases out from the muzzle end on the first 5 or so. After that I could cycle the bolt again (w/ no mag in place) and it would extract the case. These cases still had the rims damaged. The cases also show a lot of marks from the chamber. I was shooting Winchester 5.56 ammo. I did try 2 FGMM .223 rounds as well. These 2 actually were extracted and functioned correctly, but the case rims were still damaged. I was told that it is a 5.56 chamber. I have not head-spaced this gun. What should I do? What is probably causing this problem? Thanks, William |
|
Sounds like either a bad extractor, a weak extractor spring, or both I'd try replacing both the extractor and spring first. While you're doing so, check the cutout on the bolt, to make sure there's no gaebage in the cut out, or shreds of sreel left over from the cutting process. After having done that, if you're still having problems, check the walls of the fired case to see if there are tool marks from the chamber engraved on the sides. A poorly cut chamber can cause enough resistance to extraction to cause the malfunction you're describing; but it's fairly rare. My hunch is that it's an extractor or spring problem. (Edited to Add) Whoops. Just reread your post and see that you do have chanber marks on your fired cases. I'd still do the thing w/the extractor & spring, , but the rough chamber may be also part of the problem. |
|
Headspace is completed at the factory when the barrel extension is fitted to the barrel. So you cannot change your headspace when putting the rifle together. It is possible to have a bad headspaced extension from the factory. Try a heavy buffer and the extractor upgrades that shamayim suggested. |
|
Thanks for the replies. I haven't checked the head space. I don't have the gages to do so, but I'm going to try to find someone around here that does. I think its mostly the chamber, but I sure hoped a $250 barrel wouldn't have these problems. The chamber is chrome-lined as well, so I would have thought that would make it pretty smooth. I'll probably contact Gunsmoke tomorrow and get their opinion on the problem. As for the extractor stuff...I bought the bolt assembled, so I don't have any idea on how to change the extractor spring and I don't have any idea on where to get the parts for such a change. All of which, I'm sure I can figure out though. I guess I would rather just send it back to where I bought it and let them take care of it. I'll be contacting them about the my problem as well. What is a heavy buffer? I'm guessing its the buffer spring in the stock. I've got an RRA collapsible on this gun. Thanks again, William |
| sounds like a rough chamber/high gas pressure at the time of extraction. If the rims are getting ripped off. Look and see if the chamber has a mirror finish or for any marks in the brass cases from the chamber. The gas port might be too big - if that is the case, you may have to bleed off or restrict the gas system. |
Bleed off? how is this accomplished? (I had the same problem on my DPMS308. Used a Fulton Armory adjustable gas tube to fix it, but wondering about other fixes) |
|
Well, Gunsmoke thinks its a headspace problem as well as a ammo problem. The guy I got the bolt from thinks its a chamber problem. I ordered the headspace gauges from Brownells, so I'll be awaiting them to determine what's going on here. I still think it might be the chamber myself. Here's a picture of a spent case from this gun: http://www.hunt101.com/img/232926.jpg So, once I get the headspace gauges, is there anyway to tell if its the barrel that's wrong or the bolt? Does someone have the distance the end of the case should be from the barrel extension? Thanks for the help, William |
|
I guess it doesn't matter now, but GSE was banned from this site a few years back. If the extractor is ripping the case rims, then the extractor and spring have plenty of tension, its just that the case won't come out of the chamber. Most likely the chamber was reamed to 223 spec's (thats why the FGMM worked) or it was just reamed incorrectly. Have fun dealing with Ed over at GSE..... |
I have seen the gas block drilled(inline with the gas tube) and a threaded orfice with a bleed off hole drilled in it. You would have to work on the sizes to see what would work the system yet bleed off the extra gas pressure not needed for operation. Also you would have to drill the gas tube end out or make a new gas tube that is open on the end, use a set screw to hold the tube in place. And this system may be ammo sensitive with some loads but then you can always tune it with different bleed offs. But all this won't work if the chamber is rough in the first place, that is another problem. |
|
if the shoulder of the fired case measures close to the same length as a loaded rnd, it's not the gas system my guess is someone had a bbl chromed that didn't have the chamber cut oversized enough to allow for the plating.... ie: take a standard chambered bbl, get a deal on getting it chromed, and using that to up the value/sellablility of the bbl.....my experience w/ hard chrome is that it would add a couple of thou to the dimention... a headspace gauge will show that quickly, or a cast of the chamber just a thought...good luck! |
|
I got my headspace gauges in yesterday from Brownells. I ordered the 5.56 NATO gauges and got .223 gauges. Looking at their website, they list separately list .223 and 5.56, but they are both that same part number. So, are these the gauges I need? The go is a 1.4636 and the no-go is a 1.4666. The barrel is supposed to be a 5.56. I've shot the gun a few more times now and the Winchester 5.56 ammo did a little better, but after a few shots, it stuck in the chamber again. I'm still getting the rough chamber markings (or what I think are chamber markings). I also shot some lower velocity .223 ammo and it functions fine, but still showed some chamber marks and slight case rim damage. I also shot some higher velocity Black Hills .223 in it and the first round stuck in the chamber with the case rim ripped by the extractor. I stopped after that. Thanks, William |
|
Base to shoulder length (headspace) is the same for both .223 and 5.56. The differences have to to with throat (leade) length, and .223 chambers are usually cut a bit snugger then 5,56. Your guages should be fine. I know that Rock River doesn't mark their barrels, though you didn't specify rhat the one you got was supposed to be RR. You only mentioned the lower parts as being RR. Whose barrel was it supposed to be, and does it have any markings? |
|
Thanks for the info on the headspace gauges. I was going to try and find out what the exact difference between the two catridges was. I'll check the headspace tonight. The barrel is a GSE barrel hot Thanks, William |
|
Dude. Try changing the extractor. I had the same trouble with my Oly barrel and thought it was a rough chamber. I even sent it back to Oly and they sent me a new one but I still had the same problem. Then I took it to my unit armorer who looked at the extractor and replaced it with another. The lip that grabs the case rim was ever so slightly rounded and would not hook the case firmly. Works like a champ now. Get a couple to keep on hand. You should have a spare or two anyway. Good luck. Marshall |
|
So your extractor was ripping the case rims off? I would have figured that the extractor would have been just fine if it was actually taking a chunk off of the case rim. Did you have any chamber marks on your brass? I guess it might be time for me to get an EGRESS update hanks, |
|
When a cartridge is fired, the expanding brass 'grips' the chamber walls. That's why you're not supposed to have any lubricant in the chamber. I guess for a millisecond, the brass is 'stuck' to the chamber and if the extractor can't get a good 'bite' on the rim, it can tear the brass. My cases looked just like your pic. Your chamber could be a little 'rough' but I'd sure try swapping extractors before going any further. If that cures your problem, then you're fixed. Another idea is to polish the chamber a bit...using some fine lapping paste on a chamber brush but when I tried that, it made no difference. I just sent the bbl back to Oly and they sent me the new one. Imagine my surprise when I still had the same problem. I'm guessing the steel-cased Wolff ammo doesn't stick because maybe the cases don't expand as much as brass? Marshall |
|
Ok...I headspaced my gun last night. Both the Go and the No-Go went in fine. I hope I did it correctly. I took the extractor off and re-installed the bolt into the carrier. I then put the gauge into the chamber and pushed the bolt forward. The bolt locked onto both of the gauges. After reading the instructions here, I guess I kind of wasted my time and money. I guess I should have bought the field gauge as well as it seems that this is the only one that matters (for excessive head space). At least I know that the headspace isn't short. Does this answer any questions for me though? William |
|
I had exactly the same problem with my GSE barrel. Mine had a .223 "match" chamber, which was too tight for 5.56. I had to have a smith open it up just a hair. As others have said, if your extractor is taking chunks out of the rims, it is doing its job just fine. Ben |
|
I used to have a model 1 sales barrel in .223 and when I fired off some 5.56 ammo (the SA surplus) my cases would look just like that. but when I fired .223 I never had a problem. maybe(?) the chamber is just .223 (?) dunno. after I bought a 5.56 barrel I stopped having this problem. |
AR Sponsor