AR Sponsor
Posted: 3/7/2009 8:16:50 PM EDT
Not that I make a habit of it, but an occasional single load is sometimes necessary. For a semi auto pistol, I know that dropping the slide with a round in the chamber will make the extractor very unhappy. Does the AR15 have a similar sensitivity to this  Thanks!
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It's a rare situation but I did it twice on my first DCM/ CMP match.
Both times I was on the prone, rapid fire stage, I was on my second mag loaded with eight rounds and after about the second or third round I had a FTF. I immediately cleared it and fired very quickly the remaining rounds in my mag then inserted my last round and released the bolt release then fired my last round just a second or two before the cease fire signal. Found out later I had a bad mag. |
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Why is it sometimes necessary? Some AR shooters at a few matches I've attended use handloads that are slightly longer than spec. This supposedly increases accuracy by placing the bullet in contact with the lands in the barrel. There is controversy as to whether this actually works. In any event, the longer round will not fit in a standard magazine and requires that it be loaded directly into the chamber. The bolt must then be closed on a loaded chamber. Was curious as to the effect on the extractor. Thanks to all for the replies. |
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Why is it sometimes necessary? Some AR shooters at a few matches I've attended use handloads that are slightly longer than spec. This supposedly increases accuracy by placing the bullet in contact with the lands in the barrel. There is controversy as to whether this actually works. In any event, the longer round will not fit in a standard magazine and requires that it be loaded directly into the chamber. The bolt must then be closed on a loaded chamber. Was curious as to the effect on the extractor. Thanks to all for the replies. I haven't seen a detrimental effect of this on an extractor. The extractor has to jump over the rim everytime a round is chambered whether it is from the magazine or not. My findings on the accy issue is this: The 80 grain bullets are too long to fit in the magazine regardless of the bullet/lands relationship. Bullet seating length in regards to accuracy is dictated by the type of bullets and the chamber leade/freebore dims. Some bullets will shoot well when jumping a long distance to the lands, others won't. A freebore dia. that is very close to bullet dia.(.2242) will typically give better accuracy than one of a larger dia. The distance the bullet has to travel before it engages the lands is still important, but less critical with a tight freebore. OTH, a tight freebore will typically show more chamber pressure than say a 5.56 NATO chamber. The Wylde chamber is a compromise between the two. Large body, large neck dia., tight freebore dia., with a leade angle and freebore length to handle heavy bullets and because of the tight freebore dia., it will work fairly well with many different bullets as my varmint rifles are Wylde chambered and I shoot 50 V-Max, 50 Sierra spt and a few 60 grain Sierra hp. |
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The round is forced over the extractor on every shot on the AR platform. It does not use a controlled feed. This differs from most pistols where the round slips under the the extractor and not over it. Don't you mean the extractor is forced over the round? The bolt charges the next round from the magazine by pushing it into the chamber. As it reaches battery the extractor, under spring tension, expands to go over the base of the round in preparation for round extraction after firing. |
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When shooting in "High Power" matches, service rifle (meaning M-16 type), you fire both the standing or off-hand and
slow fire prone stages, single shot. Loading one round into the chamber each time. The only time you fire from the loaded mags is during the rapid fire sitting and prone stages. No problems; done all the time. Yes you can have a potential slam-fire, especially when shooting cartridges with softer primers. During the match, competitors are instructed to only close their bolts after the rifle is leveled and pointed at the berm, just in case. Dennis |
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Quoted:
When shooting in "High Power" matches, service rifle (meaning M-16 type), you fire both the standing or off-hand and slow fire prone stages, single shot. Loading one round into the chamber each time. The only time you fire from the loaded mags is during the rapid fire sitting and prone stages. No problems; done all the time. Yes you can have a potential slam-fire, especially when shooting cartridges with softer primers. During the match, competitors are instructed to only close their bolts after the rifle is leveled and pointed at the berm, just in case. Dennis +1. Keep the muzzle pointed in a safe direction and you won't have a problem. |
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I'll pile on:
The normal function of an AR extractor is to pivot so that it can slip over the rim of the cartridge. Sure, it may have to do that slightly faster in the case of dropping the bolt on a loaded chamber, but it's not that much different from normal function. The reason it's dangerous for a 1911 is because the extractor there doesn't have a pivot point; it normally doesn't move at all beyond the tension applied to it when a round slides under it and is chambered. On some pistols with pivot ejectors, it stretches the range of motion for the extractor to have to slide over a chambered round, so it's also a bad idea there - just as it would be with a mauser-type extractor in a bolt-action rifle. However, in the case of the AR, single-loading still allows the extractor to function as designed - so it's a non-issue. I suppose that enough use could result in damage to the extractor from the extra stress of slamming forward at the higher speed associated with dropping the bolt without it being slowed by the round stripped from the chamber in normal operation, but it would take a while. |
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And it's pretty much only 1911's that have issues with single feed in auto pistols. not quite true, I have heard some cases where Glock extractors have chipped from slamming the slide closed on a loaded chamber, and Glock definitely recommends NOT to do this. |
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I'm curious about this also.
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Why is it sometimes necessary? this Slow fire in service Rifle is shot single load. Some handloads (just for these stages) are loaded long with long bullets to get better performance, These loads won't fit in a mag. Slam fires are possible, while blame is often placed on soft primers I have thought sloppy reloading with primers left a bit high might be the most common culprit Dropping the bolt on a AR is proper and actually desirable from a reliability standpoint but a safe range in front of you is the correct place. |
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The round is forced over the extractor on every shot on the AR platform. It does not use a controlled feed. This differs from most pistols where the round slips under the the extractor and not over it. ^This^ The AR15 is a push feed. The extractor should be able to get over the extraction groove just fine. My concern would be the full stroke of the BCG from fully retracted to chamber without the resistance of stripping a round from the magazine. I really have no experience to prove or disprove this, but it seems to me the likelihood of s a slamfire would tend to increase if loading using this method. |
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Quoted:
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Why is it sometimes necessary? Some AR shooters at a few matches I've attended use handloads that are slightly longer than spec. This supposedly increases accuracy by placing the bullet in contact with the lands in the barrel. There is controversy as to whether this actually works. In any event, the longer round will not fit in a standard magazine and requires that it be loaded directly into the chamber. The bolt must then be closed on a loaded chamber. Was curious as to the effect on the extractor. Thanks to all for the replies. If it's done right, the throat is the most concentric part of the bore, and using the rifling helps to better align the bullet before launch. |
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Quoted:
When shooting in "High Power" matches, service rifle (meaning M-16 type), you fire both the standing or off-hand and slow fire prone stages, single shot. Loading one round into the chamber each time. The only time you fire from the loaded mags is during the rapid fire sitting and prone stages. No problems; done all the time. Yes you can have a potential slam-fire, especially when shooting cartridges with softer primers. During the match, competitors are instructed to only close their bolts after the rifle is leveled and pointed at the berm, just in case. Dennis AND this is how we fired every slow-fire stage in the USMC back in the Old Corps  . Never saw a slam-fire (not any that I know about that is).
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