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Posted: 5/1/2016 1:16:21 PM EDT
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I have a bolt action 6mm that I reloaded for years ago and then not so much for a long time. Started again and I noticed that around 1 out of every 4 or 5 rounds is difficult to extract. The bolt opens about 3/4 of the way and then sticks a bit. I can still extract the case, but I'd like to figure out what is going on and why some stick.
I don't usually notice any issue with chambering. I took it to a smith and he said maybe the chamber just needed to be polished. He has the gun now and hopefully it will help. What I'm wondering is if this might be related to how I'm sizing the brass. I'm not sure how we might have set up the die when we initially started loading years ago. I didn't change anything. I'm pretty sure we never measured headspace but maybe I just don't recall. How can I tell if I'm full length or just neck sizing? I would think difficulty chambering might be more a sizing issue than extraction but not entirely sure. Thoughts? Thanks. |
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Quoted:
What you are experiencing is usually a sign that your load is too hot. If the reloads feeds and extract when unfired without sticking, you need to lower the powder charge. Thanks for the feedback. If too hot is the problem, wouldn't it tend to be seen on nearly all rounds? I only see it about 20-25% of them. Also, all these loads are closer to minimum. For example, the min/max for H414 and 75gr is 42/47. I loaded 44 gr. There are not other signs of over pressure. Primers look fine and no case deformation. |
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Quoted:
Thanks for the feedback. If too hot is the problem, wouldn't it tend to be seen on nearly all rounds? I only see it about 20-25% of them. Also, all these loads are closer to minimum. For example, the min/max for H414 and 75gr is 42/47. I loaded 44 gr. There are not other signs of over pressure. Primers look fine and no case deformation. Quoted:
Quoted:
What you are experiencing is usually a sign that your load is too hot. If the reloads feeds and extract when unfired without sticking, you need to lower the powder charge. Thanks for the feedback. If too hot is the problem, wouldn't it tend to be seen on nearly all rounds? I only see it about 20-25% of them. Also, all these loads are closer to minimum. For example, the min/max for H414 and 75gr is 42/47. I loaded 44 gr. There are not other signs of over pressure. Primers look fine and no case deformation. It can be your sizing and case prep process. Does this brass have a history? How many times has it been cycled? What can you say about your size process in terms of shoulder datum bump? Do you use the expander? What lube do you use? Have you checked the shoulder datum on your sticky ones and then also the ones that didn't stick? I would be reluctant to let a smith remove material from the chamber unless I were sure. When I first started out, I was just learning to neck size and encountered some rounds that were difficult to close or open the bolt. The brass shoulder datum has some spring back when the brass is fresh. After some cycles, it doesn't spring back as much and there is some dispersion in this process. Some cases start having issues first, eventually the whole batch would show this issue. The whole batch doesn't get stiff on the same cycle, so that tends to fit your percentage description so far. A shoulder datum measurement would help you out in general. Also, take a look at the extractor and see if it looks rough. |
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Quoted:
It can be your sizing and case prep process. Does this brass have a history? How many times has it been cycled? What can you say about your size process in terms of shoulder datum bump? Do you use the expander? What lube do you use? Have you checked the shoulder datum on your sticky ones and then also the ones that didn't stick? I would be reluctant to let a smith remove material from the chamber unless I were sure. When I first started out, I was just learning to neck size and encountered some rounds that were difficult to close or open the bolt. The brass shoulder datum has some spring back when the brass is fresh. After some cycles, it doesn't spring back as much and there is some dispersion in this process. Some cases start have issues first, eventually the whole batch would show this issue. A shoulder datum measurement would help you out in general. Also, take a look at the extractor and see if it looks rough. Brass has 4-6 loadings. Not sure exactly as we never tracked this before. Some brass is new from once fired and has been loaded only once (well twice but that ammo hasn't be fired yet). I did not pay attention to which cases stuck, but once I get the gun back and test some more rounds I will. Your comment about older brass not "springing back" as well could be the issue here. I'll need to try and compare the older brass to the newer brass to see if there is any pattern. I'm also looking into annealing the brass and that might help renew it. I did test this on a handful of cases including some that did stick so once I have a chance to test them I might know more. Is there an easy way to measure the shoulder datum? Or do I need some specific tool like I've seen online? |
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Probably not the cause but something to check. Bolt lubrication and cleaning could be part of the problem? Good article on cleaning and lubrication of the bolt lugs, cocking and extraction cams. Just something that can cause difficulty with bolt lift.
http://www.accurateshooter.com/technical-articles/bolt-maintenance-methods-materials/ |
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Quoted:
Probably not the cause but something to check. Bolt lubrication and cleaning could be part of the problem? Good article on cleaning and lubrication of the bolt lugs, cocking and extraction cams. Just something that can cause difficulty with bolt lift. http://www.accurateshooter.com/technical-articles/bolt-maintenance-methods-materials/ Quoted:
Probably not the cause but something to check. Bolt lubrication and cleaning could be part of the problem? Good article on cleaning and lubrication of the bolt lugs, cocking and extraction cams. Just something that can cause difficulty with bolt lift. http://www.accurateshooter.com/technical-articles/bolt-maintenance-methods-materials/ Thanks. I'll give that a try. Quoted:
Have you tried checking case length after full-length sizing your cases? If you don't have an accurate idea of how many times cases were fired, some of the older cases could have stretched a bit, and that definitely could affect extraction. I do measure cases and trim the long ones after sizing. |
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What action did they build it on? Some actions have more cam power than others. The Remington 788 and 78 will often do what you describe especially when tight chambered.
Try adjusting your size die for maximum effect. You may also want to polish the chamber. It could have very lightly rusted over time. Actually more often it's dried oil or some other preservatives. This is very common with military surplus rifles that were in storage. A patch wrapped around a shotgun brush and toothpaste works good. I turn it with a cordless drill. Motor |
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Interarms Mark X is a nice 98' Mauser based action.
Since your family member built the rifle it is possible that he made the chamber to minimum spec. You may have to set up your size die to size to maximum effect. My 6mm Rem has a "tight chamber" I need to full length size with solid cam over for it. But once sized I can neck only size for a few reloadings before needing full length sized again. Motor |
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