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Reloading Techniques For Reloading


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bullet jam

 
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  #8  
Old 05-11-2006, 03:12 PM
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Re: bullet jam

[ QUOTE ]
HI BART B... so lets say i have 2 thou of jam then i go to 4 thou and then 6 thou and so on

so i take it you are not shoving the bullet in to the lands more like shoving the lands in to the bullet???

so y dose it matter if you have 2 tho or 10 thou of jam [img]/ubbthreads/images/graemlins/confused.gif[/img]


[/ QUOTE ]Colin, all these guys who've responded did such a great job explaining, I'll have to pass any credit that leaks my way on to them.
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  #9  
Old 05-11-2006, 05:54 PM
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Re: bullet jam

What they are talking about is seat your bullets .010" out farther than the jam length. That way you are sure they are in nice contact with the rifling when you close the bolt. The rifling will finish seating the bullet. This is what they are talking about. It would be the same if you set them .050" long. The bolt would just be a lot harder to close because you would be out past the cam action of the bolt. It's not that you are actually pressing the bullet .050" into the rifling. Neck tension will have a very small affect on how tight the bullet is actually jammed into the rifling due to how hard the bullets are.

You're making this much harder than it is. Just set 3 rounds really long. Force the bolt shut on all of them and then measure the overall length. From that average set your seater to seat your bullets .010" longer than your average. Done deal. Now just find the powder charge that gives you the best result. Seating into the rifling like this eliminates a variable. After you find the best powder / charge combo then you can safely back off the rifling in small increments to further fine tune the load.
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  #10  
Old 05-11-2006, 06:29 PM
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Re: bullet jam

[ QUOTE ]
You're making this much harder than it is. Just set 3 rounds really long. Force the bolt shut on all of them and then measure the overall length. From that average set your seater to seat your bullets .010" longer than your average. Done deal.

[/ QUOTE ]

I have to disagree here. Not saying who is right or who is wrong but:

Crushing bullets into the rifling and then adding .010" more is a techniqe that would leave you with an indiscriminant amount of bullet intrusion into the rifling. It would vary quite a bit depending on the neck tension, neck cleanliness and the amount of bullet shank that is in contact with the case neck.

Typically, .010" of jam (or crush fit) means .010" longer than a loaded round that just touches the rifling. A loaded round that is .010" more than a maximum crush fit could be any length at all.
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  #11  
Old 05-11-2006, 10:11 PM
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Re: bullet jam

Apparently you have never tried it. It is very precise. To get the bullet into the rifling by any measurable amount beyond jam length about takes a hammer blow to the back of the bullet. The differences in depth due to neck tension would be negligible at most. Other than my Weatherby's I do this every time I load and I keep records to watch for throat movement. The jam seated rounds usually all measure to within .001 of each other. The biggest variances are due to tip deformities if measured with calipers. When measured to the ogive in my seater they are nuts on.
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Only accurate rifles are interesting.

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  #12  
Old 05-12-2006, 12:51 AM
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Re: bullet jam

so basically what we are looking at when you have founf the OAL of your loaded bullet add 10 thou to this measurment and with the correct neck tension lets say 2 thou this is enough to sft seat.jam the bullet so they are all correctly positioned to the rifleing ??
one more question I have tried this I have 2 thou of neck tension and when I add 10 thou to my OAL the bolt shuts fine with very little pressure but when I extrcat it the OAL has lengthend as i prsume the lands have held the bullet and with minimum neck tension has allowed the bullet to be pulled out slightly,I presume this is OK when you actually shoot each round topu chamber but will it efeect anything if you keep taking the bullet in and out as over here in the UK you are not guaranteed to make a shot
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  #13  
Old 05-12-2006, 02:21 AM
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Re: bullet jam

so how you have explained it,what is the difference between soft seating and bullet jam.or are we talking about the same thing.
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  #14  
Old 05-12-2006, 04:53 AM
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Re: bullet jam

I would agree with VarmintHunter. Neck tension does matter. It also affects thr pressure spike.
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