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Discussion Starter · #1 ·
I am having custom 6.5mm bullets made that are 1.360" long and weigh 173gr. The bullets will have a #6 Spitzer design. Will my 1:8" twist stabilize it at a velocity my 6.5x55 is capable of?

Thanks, Dinny
 

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Discussion Starter · #4 ·
Re: What Twist?

I agree about the math.

Thanks, Dinny
 

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Discussion Starter · #5 ·
Re: What Twist?

Berger's book has 140gr 6.5 bullets that are longer and they recommend 1:8" twist or faster. I wonder which is more important, the length or the weight?

Thanks, Dinny
 

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Discussion Starter · #6 ·
Re: What Twist?

Uncle Steve has a calculator chart that seems to think 1:7" is best.

http://stevespages.com/twist_230_to_308.html
http://stevespages.com/page8e.htm

While Berger's online calculator seems to think 1:8" is best.

And JBM says I have a 2.051 stability value* with my 1:8" twist and a velocity of 2300fps.
*The Miller stability value. It should be between 1.3 and 2.0 to ensure stabilty (the military uses 1.5).

:-\ :-\

I think I will just shoot some and see how they do.

Thanks, Dinny
 

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Re: What Twist?

Dinny said:
Berger's book has 140gr 6.5 bullets that are longer and they recommend 1:8" twist or faster. I wonder which is more important, the length or the weight?
Length and speed are the primary determining factors for the spin needed to stabilize.
 

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Discussion Starter · #8 ·
Re: What Twist?

With that answered, I have a few more questions. Where do I find 175gr bullet data for the 6.5x55? Should I just start with low end 160gr data?

Thanks, Dinny
 

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Re: What Twist?

I`m guessing you mean 6.5 Swed, but anyway my my Sierra manual has data or you can get it at the powder manufactures web page for the powder your going to load. You can look it up on line or down load the whole manual. Here are some www.hodgon.com www.accuratepowder.com www.ramshot.com . You can down load IMR and Win. powders at Hogdon powders. I just down loaded all of them and keep them in a 3 ring binder. It is the length of the bullet vs. the diameter that matters. If you have a lead bullet and a solid copper bullet of the same weight and cal. the copper will be longer and need a faster twist.
 

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Discussion Starter · #10 ·
Re: What Twist?

How about using 175gr bullet data from the 7x57 for 6.5x55 175gr bullets? I would start at the low end and work my way up if any of you think that's a safe bet.

Thanks, Dinny
 

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NO DO NOT EVEN TRY THAT. You going from a larger case and a larger bore to a smaller case and and a smaller bore pressure would go through the roof, along with some gun parts. Did you check web pages I put on my last post????
 

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Discussion Starter · #12 ·
Yes I did. Accurate and Ramshot data are one in the same and no more help than the Hodgdon data for this application. Case capacities are different but similar. I'm not sure pressure would skyrocket. I'll keeping looking for more data, eventually something useful will surface.

http://www.ballisticstudies.com/Knowledgebase/6.5x57.html

Thanks, Dinny
 

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Discussion Starter · #14 ·

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160 grain is the heaviest any of my
data books are listing. i figured to
find something out of all these i have :(
 

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Discussion Starter · #17 ·
I went with three powders for testing and I survived. Thanks to Tim I found decent loads that even shot well. No signs of over pressure were to be seen.

All shooting was done at 50yds.

Here are pictures of the bullets. MV was around 2500 fps and all bullets were shot into a box filled with phone books that have been soaking up water for a few months. They were swollen and packed in there really hard.

This picture shows all three bullets next to one that has not been fired. They all started out at 175 grains.



This is a view of the base of the bullet and the jacket that folded around behind it.



The view from top.



This shows what it looks like after I peeled the jacket back with pliers.



Same bullet, different view.



After I broke off the jacket petals, the remaining bullet base weighed 64gr.



With the jacket petals it weighs 97.3gr.



Here's the 129gr Hornady SST from the same rifle. It should be flying around 2700fps. It out-penetrated the 175gr PSP bullets by about 3". I lost the 125gr Nosler Partition that I recovered from the box, but it penetrated the farthest and look nicely expanded much like this SST.




The bullets all penetrated 18"-20". Do you think they would perform any differently on deer shoulder bones or rib shots?

Thanks, Dinny
 

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i didn't see your yardage posted,
but i'd imagine it has enough soup
to poke a hole in the pump station
and put the brakes on mr. or mrs. deer.
good luck
 

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Discussion Starter · #19 ·
I added the range, which was 50yds.

Thanks, Dinny
 
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