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Post by gunmutt on Jan 26, 2016 16:02:47 GMT -8
How far should one bump the shoulder back? I have been having some issues with the cartridge feeding all the way and the bolt locks up. I measured a fired case using a 9mm brass to get a measurement off. I figure the .01 back would get me but is that too much
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Post by GLSHOOTER on Jan 26, 2016 17:07:41 GMT -8
How far should one bump the shoulder back? I have been having some issues with the cartridge feeding all the way and the bolt locks up. I measured a fired case using a 9mm brass to get a measurement off. I figure the .01 back would get me but is that too much 0.003 to 0.004 is ideal. Greg
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Post by gunmutt on Jan 26, 2016 18:03:38 GMT -8
Is there a maximum to bumping a shoulder back.
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Post by gunmutt on Jan 26, 2016 18:24:39 GMT -8
I am still having issues of stuck unfired rounds from time to time. If it's not the headspace of the brass could it be that my mags are scarring up the brass causing them to jam up? I am using asc and aa mags
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Post by GLSHOOTER on Jan 26, 2016 18:35:03 GMT -8
I am still having issues of stuck unfired rounds from time to time. If it's not the headspace of the brass could it be that my mags are scarring up the brass causing them to jam up? I am using asc and aa mags 90% of the time with that issue you aren't bumping the shoulders enough. The 0.003 should fix it. You asked about MAX bump. Not over 0.006 for me. I know some will run 0.008 but those are for rounds that positively absolutely MUST work. If you intend to shoot the high bump stuff like that load it maybe 3 times and throw it in the scrap bin. That's a lot of repetitive case stretch. Greg
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Post by gunmutt on Jan 26, 2016 18:44:04 GMT -8
Measuring 10 fired cases I found a spread on +/- .004. I set all cases back to the same spec with the max right at .008. I will load all rounds with light to medium loads. During my ladder test I will run single shot not through the mag and collect velocity. I will clean the chamber after about every 10 rounds or so to ensure that when they form they have the same space to open up. After this run I will check the fired cases to see if they have the same measurement using a hornady gauge that I just ordered. This batch of lapua brass has only been fired once. The next round I will reduce the amount of bump to check if the cases stick. It seems my problem might not be a headspace issue but that the mags I am using are really eating up the sides of the cases.
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Post by campguy308 on Jan 26, 2016 19:11:46 GMT -8
I am curious what kind of dies you are using. I don't have much knowledge on how much or little to bump the shoulder back. I just set my die so that the shellholder touches the die, and then maybe just a tad more. Do I need to set the die in less deep to decrease the amount of shoulder bump, or how does that work?
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Post by GLSHOOTER on Jan 26, 2016 20:07:01 GMT -8
Measuring 10 fired cases I found a spread on +/- .004. I set all cases back to the same spec with the max right at .008. I will load all rounds with light to medium loads. During my ladder test I will run single shot not through the mag and collect velocity. I will clean the chamber after about every 10 rounds or so to ensure that when they form they have the same space to open up. After this run I will check the fired cases to see if they have the same measurement using a hornady gauge that I just ordered. This batch of lapua brass has only been fired once. The next round I will reduce the amount of bump to check if the cases stick. It seems my problem might not be a headspace issue but that the mags I am using are really eating up the sides of the cases. You can smooth the lips out a bit and reach in and break the sharp edges on the back of the extension lugs. Greg
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Post by GLSHOOTER on Jan 26, 2016 20:13:12 GMT -8
I am curious what kind of dies you are using. I don't have much knowledge on how much or little to bump the shoulder back. I just set my die so that the shellholder touches the die, and then maybe just a tad more. Do I need to set the die in less deep to decrease the amount of shoulder bump, or how does that work? Doing the uptight trick on the shellholder often results in moving shoulders back too much and overworking the brass. The mentioned 3 ir 4 thousandths is what you want normally. To decrease bump back the die out. Go to www.ar15armory.com Go to the reloading area and find the sticky near the top. It is the Poor Man's Headspace Gauge. I wrote it. Follow the directions and you can set your dies up and not have to buy the Hornady set up. It'll cost you maybe $0.10. If you have ANY questions post them up and everyone can learn here. Greg
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Post by campguy308 on Jan 27, 2016 17:35:40 GMT -8
Thanks GLShooter, I will check it out. I usually neck size all my bolt rifle brass with the Lee Collet neck die until they get too tight in the chamber, then I'll full length size. Since I started loading for my 264 AR I have just been FL sizing according to the instructions with the Lee die. I will try to play with the die adjustment.
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