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Author Topic: Neck Tension  (Read 872 times)

260RemsAlot

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Neck Tension
« on: March 25, 2018, 06:32:53 AM »

Hi everyone,

Just got finished fireforming loads in my .260 rem and I'm ready to resize using my Redding bushing die. I may have prematurely purchased my bushing at .288 because I went back and measured my loaded rounds and they came out to .288.

So my question is... would this technically be zero neck tension? And would the ammo be safe to shoot? Thanks to any help because this would save me about 20 bucks from midway and I wouldn't have to wait for the new bushing to come.
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Conaso

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Re: Neck Tension
« Reply #1 on: March 26, 2018, 06:44:25 AM »

Far from being an expert, but no one was answering your question... let me try.

I wonder if you measured correctly or used the correct bullet.  The .260 Rem uses a .264 diameter bullet.
 Assuming a case-neck thickness of .014, and you didn't "turn" your necks excessively, multiply it by 2, e.g., .264+(.014*2) = .292"  Now subtracting your .288, that is probably the max neck tension - .004.  Max, but O.K. for an auto but too much for a bolt-action (.002").  Compressed bullets?

.288-.264 = .024, .024/2 = .012" case necks?  Acceptable, but I believe thin, unless you have a custom chamber.

I hope I made some sense.  Let the pros weigh in.

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260RemsAlot

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Re: Neck Tension
« Reply #2 on: March 26, 2018, 12:34:22 PM »

Hey there! Thanks for the reply much appreciated. Ya this is my first time experimenting with neck turning and neck tension, so I have a little more learning to do. I may have to check my numbers again. But yes, neck turning and custom chamber. I am using Winchester .243 cases and neck turned down to about .013". No compressed loads, either.

Without getting too complicated, my initial measurement for bushing size was done using 140 matchburner's, but this latest measurement was with 140 rdf's. So maybe that is having an effect? Not really sure how this happened, so that's what makes me think my numbers could be off. Otherwise, I may just try them out if safety isn't a concern because worst case scenario my neck tension is .002", right?

Thanks again for the help.
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260RemsAlot

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Re: Neck Tension
« Reply #3 on: April 07, 2018, 10:40:57 AM »

Just to follow up my first post... I went ahead and tried sizing my brass with the .288 bushing. When I went to seat the bullet, I noticed there was very little resistance. I then tried to push the bullet down into the case and was able to so pretty easily. I decided not to shoot the rounds and I am going to order a .286 bushing from midway.

I think either because I used a different bullet or a different seating depth is the reason the measurement changed. I figure with a .286 bushing I should be fine for a wide range of outside neck diameters.
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ericbc7

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Re: Neck Tension
« Reply #4 on: April 18, 2018, 12:21:27 AM »

You will probably want to get a few more bushing and at least one smaller.  If you are tuning your neck tension you will certainly want to anneal your brass.  The more particular you are the more often you will need to anneal.
Good luck!
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