Julien Boit Posted July 15, 2002 Share Posted July 15, 2002 Can someone tell me what's the dimension of the rim on a 223 cartridge ? I have two kind of ammos, the first don't work at all, they are made in a portuguese arsenal (I think) and don't extract at all . I measured the rim dimension and it's the same as the South African 55s i shot (brand is NGA) which works. I must say that I had two jams (failure to extract) with those in 200 rounds. The only difference I found is the bevel : On the Portuguese, it's less important than the NGA. My AR has the D-Fender. Can it come from anything else than ammo ? DVC Julien Link to comment Share on other sites More sharing options...
EricW Posted July 15, 2002 Share Posted July 15, 2002 Julien, According to my Sierra book, the case head is supposed to be .378" in diameter and .045" thick. It might be that the shoulder of the brass is too far forward and is causing a headspacing problem. When you fire, it tends to jam the case in the chamber. I had a similar problem with my reloads. I have a very tight chamber and have to bottom out my die in order to have any hope of getting my gun to cycle. Other possible causes: - Rough or dirty chamber - I think your gun (M4 - right?) is chrome-lined, so there's not much you can do about it besides clean it really well. JB Bore Paste might help scrub out any tough gunk that's in there. - Bad Extractor - the groove on your extractor may not be as "sharp" as it needs to be. You might consider replacing it. - Weak Extractor Spring/Polymer insert Hope this helps... E Link to comment Share on other sites More sharing options...
Julien Boit Posted July 15, 2002 Author Share Posted July 15, 2002 hey EricW, as far as I know the bore must not be chrome lined. People at the shop where I ordered the M4 are not too much fan of chrome lined barrels. I cleaned the barrel and the chamber after 200 rounds , in fact once after 150 rds and another time 50 rds later. I have to try the rifle now. I took a look at the extractor and didn't notice anything, but I'm not as familiar with the AR as I am with the 1911. Did you ever used the MILITEC products ? We had a demo two weeks ago at the STD nationals, and the product seems to be Ok, any experience ? Thanks DVC Julien Link to comment Share on other sites More sharing options...
EricW Posted July 15, 2002 Share Posted July 15, 2002 Hi Julien! Sorry, I wish I could say I know what MILITEC even was. Glad to hear you've got a plain barrel, at least you can try polishing out the chamber to see if that helps at all. I saw on the History Channel that failure to extract was one of the reasons the barrels were chrome-plated to begin with - kind of a quick fix for rough / dirty chambers. Hopefully Dr. Sweeney or Kelly will chime in and fix you up. E Link to comment Share on other sites More sharing options...
Julien Boit Posted July 15, 2002 Author Share Posted July 15, 2002 these are products for lubrication. http://www.militec.com they are supposed to be issued by US Navy, DEA, and lots of agencies around the world. Do you have a tip for polishing the chamber ? I know about the "final finish" from Tubb but it only for the bore, right ? DVC Julien Link to comment Share on other sites More sharing options...
EricW Posted July 15, 2002 Share Posted July 15, 2002 Julien, For polishing, JB Bore Paste or a similar product with a mild abrasive will probably be good. Polish with a back and forth motion along the axis of the bore. Using a drill or other rotating method puts the grooves in the wrong direction. The goal is to have any metal "grooves" (microscopic ones) going in the same direction as the round when it chambers. E Link to comment Share on other sites More sharing options...
gm iprod Posted July 17, 2002 Share Posted July 17, 2002 I use Militec, real slick. Must be applied to perfectly clean firearm. Preferably warmed up firearm. The oil will 'penetrate' the outer surface of metal, leaving a very thin layer. Some guns will need 2 or 3 applications for best results. You use very little. Which is good as it is about the most expensive oil per Litre I have seen. Very good product, I sell heaps here in New Zealand. Link to comment Share on other sites More sharing options...
Julien Boit Posted July 17, 2002 Author Share Posted July 17, 2002 EricW, I know what's polishing , what I meant is : do you have a tip or a special tool (mandrel) for polishing the chamber when the barrel is mounted. I have little abrasive coated tools for the dremel, but it's not the right tool for this job ( I think) because of the lack of space to work in the receiver. I thought about one thing too, maybe the chamber of my rifle has been cut to minimum specs . DVC Julien (Edited by Julien Boit at 8:34 am on July 17, 2002) Link to comment Share on other sites More sharing options...
EricW Posted July 17, 2002 Share Posted July 17, 2002 Julien, Ahhh, je comprend!! No, I don't have mandrel or anything. I just wrap patches around an old cleaning brush - a marginal solution, but it works. I'm surprised somebody hasn't come up with die-cut felt pads in various diameters that could be stacked together to approximate the shape of a chamber for polishing. Attach the stack of pads to a reciprocating air tool and voila!: a quick way to thoroughly polish a chamber. I would not be surprised if your chamber is tight - mine certainly is. Good for accuracy, bad for reliability. E Link to comment Share on other sites More sharing options...
Patrick Sweeney Posted July 17, 2002 Share Posted July 17, 2002 Have you had the chamber checked for headspace? Chambers at or under minimum can present themselves as a failure to extract or eject. I saw this a lot back when I was gun-plumbing for a living. The lucky ones had not opened up the gas port (thinking they were failing to extract from short-stroking) and a simple chamber ream solved the problem. With a chromed M4 barrel, the only way to adjust headspace would be with a selection of bolts to swap while measuring. Link to comment Share on other sites More sharing options...
Julien Boit Posted July 18, 2002 Author Share Posted July 18, 2002 As the rifle passed through a test for approbation, (All the guns have to be checked in the proof house of Saint-Etienne before selling in France) I suppose that the chamber was checked for specs (at least the minimum specs). Plus I know that the shop where i bought the rifle are bench rest specialist, they test all the rifle they sell with gauges. I'll try without the D-Fender and also in applying some spray lube on the cases. I'll also try with an O-ring under the extractor (like the D-fender but a little bigger one), I must find one in my stock (almost 15000 differents O-rings from various dimensions). I also made some measurements on the rim of my cases : diameter .38 thickness .04 Are they undersized ? DVC Julien (Edited by Julien Boit at 5:29 am on July 18, 2002) Link to comment Share on other sites More sharing options...
Julien Boit Posted August 26, 2002 Author Share Posted August 26, 2002 I tried something different this weekend, I shot my M4 with a sound suppressor, It works better than without, except for the point of Impact at long range. I suppose that more gases are coming back and allows better functionning, I'm even sure because everytime I shot, I received some gasses though the charging handle. Have you ever seen that ? I thought about using a longer gas tube such as the Pigtail, what do you think ? DVC Julien Link to comment Share on other sites More sharing options...
BPiatt Posted August 31, 2002 Share Posted August 31, 2002 Hold up on your posishing..... Here's one problem that has been creeping up lately. Winchester white box (imported lots) and some of the steel cased russian ammo has the following. Check your ammo. Depending on your rifle and chamber lead...(distance from chamber to rifling) some of the imported ammo are oversize. The mfg will tell you it's SAMMI spec, and yes the cases are, but there is no SAMMI spec for the OGIVE (contour) of the bullet. If the bullet is jammed into the rifling, pressures go way high and can cause extraction problems. If it's a real short lead, the case may not chamber fully, having the extractor partially engaged. Take a loaded round, mark the bullet with a dark magic marker. Chamber the round and then take it out. Look for rifling marks on the bullet. If there are little square marks on the bullet, it's jamming into the rifling. You can run a "chamber guage" in a gun and it will not show you this problem. Hopefully this is what you have and all you have to do is change ammo. Bruce Piatt Link to comment Share on other sites More sharing options...
BPiatt Posted August 31, 2002 Share Posted August 31, 2002 On the lines of ammo, another issue I didn't mention is the use of the laquered imported ammo. I'd avoid it at all costs. It's a good buy, you can shoot it all day, but when the gun cools, (and you don't clean it good) the laquer turns to glue in the gun. while the gun is hot, it'll run but don't trust it after that. While I don't have documentation on this, all but one of my guns are good quality match barrels. I just don'f feel right putting a stell case into my chamber, theoretically scratching it up. Can anyone confirm this or am I being anal? Bruce Link to comment Share on other sites More sharing options...
kellyn Posted August 31, 2002 Share Posted August 31, 2002 Bruce, I cannot "confirm" it but I'm with you. I would never put a steel case in any of my barrels. Lake City and Winchester are just fine, thank you very much. I have seen gases come through the charging handle. A little gasket goo (ATV I think) and you're good to go. Link to comment Share on other sites More sharing options...
EricW Posted September 1, 2002 Share Posted September 1, 2002 I've heard anectodal reports of the steel cases chewing through extractors on AR's. I try to be pretty practical ("the gun is just a tool") but lacquered steel case ammo just seems like a bad bad idea. AR chambers are a pain enough to clean with out that gook. E Link to comment Share on other sites More sharing options...
Julien Boit Posted September 2, 2002 Author Share Posted September 2, 2002 Thank you guys . Bruce, I'll check it as you mentioned. Thanks DVC Julien Link to comment Share on other sites More sharing options...
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