beltjones Posted September 10, 2011 Share Posted September 10, 2011 I was shooting AAA .40 remanufactured ammo at Area 4 last week, and had three pretty bad malfunctions that I think may have cost me the match in L10. I thought I had diagnosed the problem to be me not seating magazines properly, but after today's range session I'm not so sure. I brought along 150 rounds of AAA .40 leftover from the match (all chamber checked - just like the match ammo), 200 rounds of Remington UMC 180gr, and 200 rounds of WWB 165gr. I had three (3) malfunctions with the AAA, and the UMC and WWB ran fine. The malfunctions were all exactly the same today as they were last week: The rounds get hung up going into the chamber, in what some people call a "three point malfunction" where the tip of the bullet is touching the top of the chamber, the casing is touching the top of the ramp, and the rim is touching the bottom of the breachface. The main difference I can see is that the AAA ammo is much less round at the tip than the other rounds. Other info: I have a diligent cleaning process, and I completely de-gunked my extractor before and after Area 4. The recoil spring is a 15 lb ISMI. Has this sort of thing happened to anyone else? I'm a little nervous considering I have 500 rounds of the same ammo waiting for me in Las Vegas... Link to comment Share on other sites More sharing options...
Biloxi23 Posted September 10, 2011 Share Posted September 10, 2011 Yes. Through the end of 2010 and into 2011 my G35 wasdoing exactly that. It was a stock barrel, and would hang up no matter if it was factory ammo, or my reloads. At the time I was using Winchester 180 FMJ truncated cone bullets, loaded to 1.120 to 1.122. I tried changing springs, in the gun, in the mags, wiht Dawson extensions, with stock basepads and any combination thereof. Then a friend gave me some Precision 185 grain, moly coated bullets. They have a round nose type contoyr with the tip flat. I also began loading them out to 1.135. The work fine now and I use an ISMI stainless guide with a 15# ISMI spring. I still haven't figured out exactly why the psitol doen't want to run wth factory ammo. Link to comment Share on other sites More sharing options...
RangerTrace Posted September 10, 2011 Share Posted September 10, 2011 This probably isn't the issue, but one thing you'll see with reloaded ammo is an extractor mark on the case. Some are worse than others. Seems to me, if your gun didn't like the TC bullets, it wouldn't feed any of them. Maybe those few had a deep gouge in the case? Link to comment Share on other sites More sharing options...
Duane Thomas Posted September 10, 2011 Share Posted September 10, 2011 The bullet profile you're using in the AAA ammo is called a truncated cone (TC) because that's what the shape is like: take a cone and cut the top off it. (In this case it would be a jacketed truncated cone - JTC.) This bullet profile is notorious for causing exactly the malfunction you've described. While a lot of people think a cartridge, ideally, "feeds smoothly into the chamber" that's not what actually happens. What actually happens is that as the cartridge leaves the magazine, first the underside of the bullet hits the feed ramp and bounces up off that. then as the cartridge enters the chamber the top of the bullet hits the top of the chamber and bounces down, straightening it out enough that it can slide all the way into the chamber and the action can close around it. What happens with a TC bullet is that when the top of the bullet hits the top of the chamber, flat surface meets flat surface, and instead of bouncing off to complete chambering, it just stops. At that point you wind up with what we call a "45 degree nose up stoppage." The solution is to go to bullets with a more rounded, feed reliable ogive. TC bullets in an auto pistol are just malfunctions waiting to happen. Link to comment Share on other sites More sharing options...
beltjones Posted September 10, 2011 Author Share Posted September 10, 2011 The bullet profile you're using in the AAA ammo is called a truncated cone (TC) because that's what the shape is like: take a cone and cut the top off it. (In this case it would be a jacketed truncated cone - JTC.) This bullet profile is notorious for causing exactly the malfunction you've described. While a lot of people think a cartridge, ideally, "feeds smoothly into the chamber" that's not what actually happens. What actually happens is that as the cartridge leaves the magazine, first the underside of the bullet hits the feed ramp and bounces up off that. then as the cartridge enters the chamber the top of the bullet hits the top of the chamber and bounces down, straightening it out enough that it can slide all the way into the chamber and the action can close around it. What happens with a TC bullet is that when the top of the bullet hits the top of the chamber, flat surface meets flat surface, and instead of bouncing off to complete chambering, it just stops. At that point you wind up with what we call a "45 degree nose up stoppage." The solution is to go to bullets with a more rounded, feed reliable ogive. TC bullets in an auto pistol are just malfunctions waiting to happen. That makes perfect sense. Man I love this place! Link to comment Share on other sites More sharing options...
Duane Thomas Posted September 11, 2011 Share Posted September 11, 2011 We live to serve. Link to comment Share on other sites More sharing options...
RangerTrace Posted September 11, 2011 Share Posted September 11, 2011 (edited) Except that I've shot thousands (10K or so) of those JTC's through my S_I guns without issues.... Both STI and SVI alike...... Edited September 11, 2011 by SV-COP Link to comment Share on other sites More sharing options...
beltjones Posted September 11, 2011 Author Share Posted September 11, 2011 What length? The long stuff or the standard stuff? Link to comment Share on other sites More sharing options...
RangerTrace Posted September 11, 2011 Share Posted September 11, 2011 I never bought any of the 1.180 stuff, only factory length... Link to comment Share on other sites More sharing options...
beltjones Posted September 11, 2011 Author Share Posted September 11, 2011 If only I had won Nic Neel's raffle gun... all my problems would be solved! Link to comment Share on other sites More sharing options...
DougCarden Posted September 11, 2011 Share Posted September 11, 2011 Dumb question: Do you have problems running the ammo with stock springs for the gun, or do you have the same malfunctions with the stock heavier spring and the lighter ones? Something to look at.... DougC Link to comment Share on other sites More sharing options...
Duane Thomas Posted September 11, 2011 Share Posted September 11, 2011 Except that I've shot thousands (10K or so) of those JTC's through my S_I guns without issues.... Both STI and SVI alike...... This is not a no-exceptions rule. There are some guns that will feed TCs just fine. But if the OP's gun is having that particular malfunction with that particular bullet profile, obviously his gun is not one of them. Link to comment Share on other sites More sharing options...
beltjones Posted September 11, 2011 Author Share Posted September 11, 2011 Dumb question: Do you have problems running the ammo with stock springs for the gun, or do you have the same malfunctions with the stock heavier spring and the lighter ones? Something to look at.... DougC During the match I thought that might be the case, and after I trashed a stage for the second time due to a malfunction I swapped in a stock recoil spring. I thought the problem was fixed until I had another malfunction on the first stage the following day. It seems to happen regardless of springs, magazines, and everything else I can think of. The only variable that seems to be consistent is the ammo. Link to comment Share on other sites More sharing options...
RangerTrace Posted September 11, 2011 Share Posted September 11, 2011 The bullet profile you're using in the AAA ammo is called a truncated cone (TC) because that's what the shape is like: take a cone and cut the top off it. (In this case it would be a jacketed truncated cone - JTC.) This bullet profile is notorious for causing exactly the malfunction you've described. While a lot of people think a cartridge, ideally, "feeds smoothly into the chamber" that's not what actually happens. What actually happens is that as the cartridge leaves the magazine, first the underside of the bullet hits the feed ramp and bounces up off that. then as the cartridge enters the chamber the top of the bullet hits the top of the chamber and bounces down, straightening it out enough that it can slide all the way into the chamber and the action can close around it. What happens with a TC bullet is that when the top of the bullet hits the top of the chamber, flat surface meets flat surface, and instead of bouncing off to complete chambering, it just stops. At that point you wind up with what we call a "45 degree nose up stoppage." The solution is to go to bullets with a more rounded, feed reliable ogive. TC bullets in an auto pistol are just malfunctions waiting to happen. This was the only part I was referring to... Link to comment Share on other sites More sharing options...
twodownzero Posted September 11, 2011 Share Posted September 11, 2011 The solution is to go to bullets with a more rounded, feed reliable ogive. TC bullets in an auto pistol are just malfunctions waiting to happen. But .40 was designed for TC bullets, so for better or worse, that's what is mostly available out there. Link to comment Share on other sites More sharing options...
Biloxi23 Posted September 11, 2011 Share Posted September 11, 2011 Duane is exactly right. I have owned 6 .40 Glocks. Two would eat anything you fed it, and the other four were picky as a rich girl. I have owned a bunch of Glocks in other calibers also, and the forties are the only ones that seem to have the 45 degree failure to feed. My G24 feeds the 185 Precisions at whatever COAL I decide to use, but the jacketed TC's will FTF at the worst possible moments. Link to comment Share on other sites More sharing options...
Duane Thomas Posted September 11, 2011 Share Posted September 11, 2011 But .40 was designed for TC bullets, so for better or worse, that's what is mostly available out there. Well, I wouldn't say it was "designed for TC bullets," that's overstating a bit, but yes, if memory serves, the initial loads for ,40 S&W did, and many loads even today do, feature TC profile bullets. That was a bad decision back then, and the fact that most .40 bullets have a TC profile today is a bad thing, too. Link to comment Share on other sites More sharing options...
gg35 Posted September 12, 2011 Share Posted September 12, 2011 I have shot appr. 6000 rds through glock 35 gen 4 and 1500 through glock 23 gen 4. 90% of these were Montana Gold 165 TC. I load to 1.130 length and 140 Power Factor. If I drop any lower on the PF I get a short cycle that ejects the fired case and leaves the next round jammed at the top or sticking straight up in the ejection port. It appears that the slide comes back just enough to eject the fired case, but does not quite get behind the case and kind of rakes it out of the magazine leaving it jammed up. Link to comment Share on other sites More sharing options...
Flexmoney Posted September 12, 2011 Share Posted September 12, 2011 When was the last time you replaced the mag springs? What base pads and springs are you running? Link to comment Share on other sites More sharing options...
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