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Posted: 4/4/2008 3:03:27 AM EDT
| Last month I purchased a “parts” rifle with a RRA lower and other seeming quality components. I have only made it out to the range once, but was able to put several hundreds rounds downrange and establish a decent zero. I shot primarily 55gr and 62gr fmj ammo. I bought these rounds from “The Brass Kings” out of Michigan at a local gun show. The weapon and ammo functioned flawlessly and I was very pleased with both. However, the other day I took delivery of a 1000 rd box of XM193 ammo stamped “Lake City” with the NATO symbol. I uploaded some magazines and chambered a round of the new ammo. When I attempted to expel this round the charging handle would not pull back. I’m not sure how hard I can pull without damaging anything, so I didn’t try too hard to force things. I eventually pushed through the rear pin and opened up the receiver and physically pushed back the entire bolt assembly to free the round. Without going into unnecessary detail this was all done why keeping the barrel pointed in a safe direction, etc. This happened with a couple of rounds. What is the problem? Insufficient lubrication? Bad ammo? Bad gun? Bad operator? Thanks for any input. |
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You did not inadvertently "jam" a 5.56mm round into a 223 chambered rifle did you? (as you mentioned it's a parts is part rifle of an unknown builder) Note: LC is quality surplus rounds but are clearly 5.56 spec ammo - YOU have reviewed the Ammo Faq tacked atop the Ammunition forum haven't you? Particularly question #2.....  mike eta - here I retrieved the #2, but you should still print this item out and review the "whole" FAQ: Q. What is the difference between 5.56×45mm and .223 Remington ammo? In the 1950's, the US military adopted the metric system of measurement and uses metric measurements to describe ammo. However, the US commercial ammo market typically used the English "caliber" measurements when describing ammo. "Caliber" is a shorthand way of saying "hundredths (or thousandths) of an inch." For example, a fifty caliber projectile is approximately fifty one-hundredths (.50) of an inch and a 357 caliber projectile is approximately three-hundred and fifty-seven thousandths (.357) of an inch. Dimensionally, 5.56 and .223 ammo are identical, though military 5.56 ammo is typically loaded to higher pressures and velocities than commercial ammo and may, in guns with extremely tight "match" .223 chambers, be unsafe to fire. The chambers for .223 and 5.56 weapons are not the same either. Though the AR15 design provides an extremely strong action, high pressure signs on the brass and primers, extraction failures and cycling problems may be seen when firing hot 5.56 ammo in .223-chambered rifles. Military M16s and AR15s from Colt, Bushmaster, FN, DPMS, and some others, have the M16-spec chamber and should have no trouble firing hot 5.56 ammunition. Military M16s have slightly more headspace and have a longer throat area, compared to the SAAMI .223 chamber spec, which was originally designed for bolt-action rifles. Commercial SAAMI-specification .223 chambers have a much shorter throat or leade and less freebore than the military chamber. Shooting 5.56 Mil-Spec ammo in a SAAMI-specification chamber can increase pressure dramatically, up to an additional 15,000 psi or more. The military chamber is often referred to as a "5.56 NATO" chamber, as that is what is usually stamped on military barrels. Some commercial AR manufacturers use the tighter ".223" (i.e., SAAMI-spec and often labeled ".223" or ".223 Remington") chamber, which provides for increased accuracy but, in self-loading rifles, less cycling reliability, especially with hot-loaded military ammo. A few AR manufacturers use an in-between chamber spec, such as the Wylde chamber. Many mis-mark their barrels too, which further complicates things. You can generally tell what sort of chamber you are dealing with by the markings, if any, on the barrel, but always check with the manufacturer to be sure. Typical Colt Mil-Spec-type markings: C MP 5.56 NATO 1/7 Typical Bushmaster markings: B MP 5.56 NATO 1/9 HBAR DPMS marks their barrels ".223", though they actually have 5.56 chambers. Olympic Arms marks their barrels with "556", with some additionally marked "SS" or "SUM." This marking is used on all barrels, even older barrels that used .223 chambers and current target models that also use .223 chambers. Non-target barrels made since 2001 should have 5.56 chambers. Armalite typically doesn't mark their barrels. A2 and A4 models had .223 chambers until mid-2001, and have used 5.56 chambers since. The (t) models use .223 match chambers. Rock River Arms uses the Wylde chamber specs on most rifles, and does not mark their barrels. Most other AR manufacturers' barrels are unmarked, and chamber dimensions are unknown. ETA #2 - fwiw. should you get your rifle hung up like this again here's two ways to get it unstuck 1. FIRST off remove the magazine and remember you have a loaded round in the chamber so always keep the rifle pointed in a safe direction. 2. From a kneeling position with rifle pointed upward and downrange, left hand on the front HG with your right hand on the charging handle in the normal manner (depressing the release and careful to remember to keep your head away from the muzzle) - with stock 1-2 foot off the ground, using your left hand (right still w/ pressure on the CH) strike the rifle "butt" first down onto the ground (watch that muzzle!) If at first you don't succeed try again, striking the ground harder (2-3 times may be necessary) 3. this will normally dislodge the errant round IF it does not Then do this (and you'll need a wooden handled ball-peen hammer (I always carry one in my range bag & nope it don't need to be a 2lb one here - med will do fine) 1. With mag removed have a friend hold the rifle vertically - buttstock resting on the shooting bench. 2. Take the ball peen hammer and as your friend is pinching the CH release (and pressing downward) on the left side of the rifle and hloding the rifle vertically - YOU (w/ left hand) place the wooden end of the ball peen hammer vertically onto the oppsite ear of the CH and once you have the handle centered STRIKE the rounded head of the ball peen with the palm of your right - as note above if one strike don't do it the hit her harder - (again watch that muzzle!!! as the rifle has a round in the chamber) careful to keep the handle centered and hold the hammer as close to rifle as possible so that the "force" here is straight downward along the axis of the rifle.... This has never fail to dislodge an errant "stuck" round in the chamber for me and should work for you... And nope, I have never damaged a rifle using the second method here and THIS is the method I prefer ; as only in a combat or emergency situation have I imparted the "first" method above to you (mainly 'cus I ain't partial to "bashing" my AR around - but there are times when it's what's called for)
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| my wife's 7.62x39 upper did this. The forward assist had some sharp edges and was sticking a bit. Somehow--don't know how--when the bolt slammed forward, the f/a would stick out a hair and engage the bolt. A shot of CLP and working it for a minute cleared it right up. |
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my old RRA upper used to do this sometimes. It was something I learned to live with. To get it unjammed I would have a friend pull the Charging handle while I used a brass punch and hammer to lightly tap downward on the side of the BCG until you dislodge the BCG enough to just pull it all the way out with the CH. Worked every time and it was taught to me by a gunsmith... I think it's the chamber of the barrel IMO. I think this because after I replaced the barrel on the gun that did it, the problem went away. But I also replaced the upper reciever  Good Luck |
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