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Posted: 7/8/2013 8:27:46 PM EDT
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I have been hand loading for my 3 AR's and many other friend's guns. I only have this issue with one gun of mine. For this reason, I am certain it is not an ammo issue. I have a case gauge that I use to check the rounds and they come out right in between the high and low measurements. They are NOT too long.
I have recurring stuck case issues with this gun. Most always when clearing an unfired cartridge to show clear. Less often will a fired case fail to extract. I thought the chamber was simply dirty, but it happens even when I have really cleaned it out well, just not as often. I feel that the chamber is very short and the head space is at a minimum. So when a slightly long cartridge is loaded, or the chamber has any dirt in it, the case sticks far easier than other guns. What I don't know or have the means to do is: A) measure the head space B) if it is tight, to re-secure the barrel with a longer head space. Can you help with A or B or do you have any other ideas as to the cause or solution? One solution may be to simply make special runs of ammo for this gun, with case shoulders pushed further back. That seems like a not good solution, but it may work until I can afford some costly gun smith work. Please re-read this part: I only have this issue with one gun of mine. For this reason, I am certain it is not an ammo issue. Thanks! |
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I wouldn't rule out a reloading issue, does it fire factory ammo without a problem? If it does, than you may need to
invest in small base dies that size the brass down more than a regular die. If it doesn't fire factory ammo without problems you should check headspace with a go gauge and a no go gauge. If it fails those test than you know that your issue is the headspace. That would be my approach to this problem. |
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Don't buy a different sizer die until you understand the problem. Properly adjusted standard dies will fix the headspace problem 9999 times out of ten thousand.
You can't readjust the headspace of an AR barrel after the fact (not without drama), it is set by the chamber, the barrel extension, and the bolt. However, what you could do is try a different bolt in your rifle, and if that clears up the problem, double check by putting the bolt from the problem gun into a different rifle. You also don't need to buy a set of adjustable gages from Hornady or Sinclair, although they are nice because they attach to the caliper jaws. Find a bushing with a 5/16th's inner diameter. The length has to be long enough to extend past the case mouth when the bushing is slipped over the case shoulder. Get a few (5 or so) cases fired in the rifle. Place the bushing on a case. Put the bushing plus case between the caliper jaws and take a measurement; this will a comparator measurement. Repeat for each case, record the measurements, and calculate the average. (There's a thread in Reloading with sketches, but I'll have to hunt it up.) The cases sized for that rifle must be sized so they are 0.0015 to 0.002 inches shorter than the comparator measurement. A case that is just 0.0005 to 0.001 inches too long will either cause hard chambering, hard extraction, or both. The Wilson and Lyman fixed drop in case gauges cause the sizer to be set up for 0.008 inches of shoulder set back. I'm not a fan, I prefer an actual measurement and control over the set back. Most of the time when this occurs the cause is lube practice during case sizing. The expander ball of a sizer die will pull the case shoulder out slightly if it drags on the inside of the case neck when withdrawn. The cure is either a little lube inside the case neck, a carbide expander ball, or both. If your cases are gaging okay, then I don't know that this is your problem. I have two handguns chambered for .22 Jet. The chamber in one is so short that I had to remove material from the top of the shell holder in order to get the die down far enough to push the shoulder back so the cases will chamber. If you have more than one #10 or equivalent shell holder, compare the thickness of the top flange, and use the thinner one to size a few cases. Some people turn the bottom of the die, but I'm an advocate of modifying the least costly part. A less likely issue is excess crimp on the bullet. I do not crimp .223 Rem ammunition, it's simply not necessary when the neck tension is correct. Threads that might help; do a search for "gauge" in the Reloading forum: http://www.ar15.com/forums/t_6_42/400691_Full_length_sizing_question.html&light=gauge |
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Quoted:
I have never heard of a chamber cast. How would you go about doing that? First you need cerro-safe, or a similar, low-temp fixturing alloy. You can purchase that from brownells or other gun supply type stores. Stuff a patch or patches in the barrel just past the throat of the chamber. The plug needs to be pretty much watertight, at least for a short while. Melt the alloy in hot water or over a low flame and with the barrel standing upright, pour the alloy into the chamber. Try to be neat, and don't fill up any further than the very end of the chamber. You don't want to let it splash out into the locking lug recess in the barrel extension. Let it solidify and push the casting out with a cleaning rod or wooden dowel. Cerro-safe, for one, has a property where it shrinks slightly immediately after hardening to make removal easy, then swells back to the EXACT chamber dimensions as it comes down to room temperature. You'll wind up with something a bit like this (not my pic) 
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Cerrosafe has to be measured a hour after initial casting. After a long wait, it changes shape and is not usable for chamber measurement.
A casting won't tell us much with precision without some means of taking accurate measurements of the lengths, which gets us back to comparators. |
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I have had the same problem (that is, getting an ufired round out), and traced it back to a headspace problem. The case was too tight, such that when the locking lugs engaged, they did not want to un-engage. In my case, I also had an occasional failure to RTB, as the headspace was tight enough that slight differences in case lip thickness would not allow the lugs to fully turn--it was trying to remove these rounds that I could not get the lugs to un-engage. I found that swapping out the bolt (or BCG was enough to fix the problem.), OF COURSE, checking for excess headspace in the rifle that I swapped the BCG out of. I know check for both excessive and too little headspace. |
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