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Thread: Neck Sizing.. tight chambering on 1st reload???

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    Default Neck Sizing.. tight chambering on 1st reload???

    I neck sized once fired brass and ran the unloaded brass through my Rem 700 to make sure it wasn't too tight. They all went through just fine. Now I loaded a round and it seems very tight to chamber. Seems like the brass just below the should is tighter because it got real shiny there after I chambered the round a few times. Is this abnormal? I thought they would be tight, but only after a few re-loads on the brass. Is there anything unsafe about using rounds that are tight in the chamber? Lastly, are there "real world" benefits of neck sizing as opposed to just using full size and backing off the die a bit so it just bumps the shoulder?

    Thanks,
    Mike

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    Member marshall's Avatar
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    I do the second method with my personal rifles, great results. I bump the shoulder back .002 for reliable feeding. Never an issue with cycling the bolt and minimum abuse on the brass. I'm loading for hunting applications not bench rest matches.

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    You're neck sized brass fits the chamber fine without being tight?

    If so and only after seating a bullet does the body of the brass just below the shoulder fit tight. Then I'll say your problem is not the neck sizing but the seating/crimping operation.

    Yes that is abnormal. I think the crimping ridge or just the seating pressure is pushing the neck back into the case just slightly and that forces the shoulder angle to push the upper body/shoulder junction out or expand the body diameter slightly and that makes the tight fit. You may find that only some cases do this.

    Are you using a neck sizer or just partial sizing/neck sizing with the full length die? Either way will work fine but be sure to size to the bottom of the neck with the f/l die.

    Points that may help:

    *Back off the seating die body a turn and screw the seating stem down to get back to your correct seating depth.

    *Trim all cases to the same length.

    *Chamfer the case mouth inside to allow easy seating of the bullet.

    The advantage of neck sizing over f/l sizing is just that we don't set the shoulder back. You can accomplish the same thing with the f/l die by just sizing down to the neck and not touch the shoulder. Or if you have equipment to measure the amount of shoulder set back (bump) then the .002" is the dimension, as Montana has said. Often partial sizing works better because we are sizing the body slightly which insures ease of chambering even after several times fired. The caution here again is to not set the shoulder back . Headspace is .006" and most dies will sized down to the minimum and with a maximum SAAMI chamber the case will then stretch .006" each firing. That isn't good for the brass.
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  4. #4

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    Murphy,
    I used just a neck sizer and I could clearly see that only the neck was sized, the neck sizer didn't touch the shoulder. Also, I did exactly the three things you said, I'm positive the seating die never touched the case to crimp it. The bullet seated very easily too, I didn't need to push at all. Maybe it was just a fluke. I'll load a few more to see if they also have the problem. I just didn't want to load twenty and then realize they were all useless. How many times can you generally neck size brass and still have relatively easy chambering?

    Thanks again,
    Mike

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    Quote Originally Posted by MikeStaten View Post
    Murphy,
    I used just a neck sizer and I could clearly see that only the neck was sized, the neck sizer didn't touch the shoulder. Also, I did exactly the three things you said, I'm positive the seating die never touched the case to crimp it. The bullet seated very easily too, I didn't need to push at all. Maybe it was just a fluke. I'll load a few more to see if they also have the problem. I just didn't want to load twenty and then realize they were all useless. How many times can you generally neck size brass and still have relatively easy chambering?

    Thanks again,
    Mike
    There really isn;t a number. It depends on the pressure of the fired round. This is the biggest factor, pressure. It also depends on the brass, how good or how bad it was from the start. Some brass is just better. It is all about the anneal gradient of the case. If it continues to spring back to original shape (shrink after expanded by firing pressure) after a dozen firings neck sizing is all that is needed. Obviously at some point the brass will work harden, loose its elasticity (is that a word?) and this may occur at the neck, the body or the base at different times. Also the chamber of the rifle will come into consideration. If slightly over sized and allows the case to expand .004" at the body, it likely won't ever spring back enough allow it to rechamber without f/l resizing. Just the luck of the draw with that. Certainly moderate loads make brass last much longer.

    I would say that your neck sizer may not be sizing the upper body (normally the don't) and the chamber dims at that point may be slightly tight. Just as a possibility, this is sort of stacking tollerances. Die on the larger end chamber on the smaller end. I wouldn't worry about it yet, load some more. I think it would be safe to shoot if it is only the upper body that is tight. Measure at that point immediately upon firing to get a good diameter dimension at that upper body then measure your fully loaded rounds. After firing the case will take the shape of the chamber but would normally be larger than a loaded and resized round. We would need to watch if the neck was tight in the neck of the chamber with a bullet seated. You aren't seating 7mm bullets in your 270 are you? Don't laugh, I 've seen it done.
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    Quote Originally Posted by Murphy View Post
    There really isn;t a number. It depends on the pressure of the fired round. This is the biggest factor, pressure. It also depends on the brass, how good or how bad it was from the start. Some brass is just better. It is all about the anneal gradient of the case. If it continues to spring back to original shape (shrink after expanded by firing pressure) after a dozen firings neck sizing is all that is needed. Obviously at some point the brass will work harden, loose its elasticity (is that a word?) and this may occur at the neck, the body or the base at different times. Also the chamber of the rifle will come into consideration. If slightly over sized and allows the case to expand .004" at the body, it likely won't ever spring back enough allow it to rechamber without f/l resizing. Just the luck of the draw with that. Certainly moderate loads make brass last much longer.

    I would say that your neck sizer may not be sizing the upper body (normally the don't) and the chamber dims at that point may be slightly tight. Just as a possibility, this is sort of stacking tollerances. Die on the larger end chamber on the smaller end. I wouldn't worry about it yet, load some more. I think it would be safe to shoot if it is only the upper body that is tight. Measure at that point immediately upon firing to get a good diameter dimension at that upper body then measure your fully loaded rounds. After firing the case will take the shape of the chamber but would normally be larger than a loaded and resized round. We would need to watch if the neck was tight in the neck of the chamber with a bullet seated. You aren't seating 7mm bullets in your 270 are you? Don't laugh, I 've seen it done.
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    Quote Originally Posted by MikeStaten View Post
    Now I loaded a round and it seems very tight to chamber. Seems like the brass just below the should is tighter because it got real shiny there after I chambered the round a few times. Is this abnormal?
    I think MURPHY nailed it. If your seating die is down to far or you set it with a short piece of brass then your long cases will get pushed down and bulge while you seat the bullet. This will make chambering your round difficult.

    I should have read your original post more carefully. It's the "tight to chamber" that points to unequal brass length or partial crimping.

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    I'm going to chamber an unloaded case a few times and see if it fits. Then take measurements just below the shoulder. Then do the same with the same case loaded. I definitely have the seating die adjusted so it doesn't touch the case mouth so I don't think crimping is the issue. Thanks for all the info, should be able to provide some feedback as soon as I load the next case.

    Thanks!

    Mike
    Last edited by MikeStaten; 04-09-2009 at 15:52. Reason: typo

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    Quote Originally Posted by Murphy View Post
    You aren't seating 7mm bullets in your 270 are you? Don't laugh, I 've seen it done.
    Wow Murphy, you've seen it all. A .284 in a .277 hole, that's kinda like parking a Greyhound bus in a dog house...

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