Twist Rate, Pill Weight and Stability

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Re: Twist Rate, Pill Weight and Stability

Post by marksman » 23 Oct 2018, 7:45 pm

Gaznazdiak wrote:I'm not trying to be argumentative here marksman, I appreciate your input, but if you look closely at the pics the uncrated one has an even, round profile from the outside edge and over into the pin impression, whereas the cratered one is distinctly flattened around the crater.

The pin impression on the uncatered is also far deeper than the other, which looks to my barely tutored eye to have flowed under force into the firing pin hole in the bolt.


I would suggest that your firing pin hole is a bit sloppy causing the cratering
the edges of the primers are both rounded, no pressure
rem 7.5's are a good primer and are supposed to be a thicker cup but they measure 20 thou and the cci's 25 thou
honestly try the cci br4 or 450 mag primers with that load
check out these primers from factory ammo

Image

the hornady has rounded edges on the primer but a very slight crater, but I would consider it mild and safe
the s&b is totally flattened and probably has an enlarged primer pocket, this I would say is on the edge but I must assume it is safe as it is factory
I would never load to this level of flattened primer even though I don't believe in looking at primers for pressure
measure the case head its much more reliable
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Re: Twist Rate, Pill Weight and Stability

Post by Gaznazdiak » 24 Oct 2018, 9:50 am

As nobody was able to offer an explanation that definitively disproved pressure, I did some googling and much more reading.

Every source, without exception said that a common cause is ill fitting firing pin, but every source also said that if factory loads or your minimum loads do not cause cratering and hotter hand loads do, pressure is the only logical culprit.

So erring on the side of prudence and safety, I can only go by the majority of opinion.

Thanks to those who took the time to offer some advice on this problem.
fideles usque ad mortem
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Re: Twist Rate, Pill Weight and Stability

Post by SCJ429 » 24 Oct 2018, 6:30 pm

You can get the bolt firing pin hole bushed if you are concerned about it. Was it a Remington action?
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Re: Twist Rate, Pill Weight and Stability

Post by marksman » 24 Oct 2018, 6:47 pm

its good to see that you will make your own mind up and err on the side of caution Gaz
you did it your way :thumbsup: :drinks:
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Re: Twist Rate, Pill Weight and Stability

Post by marksman » 24 Oct 2018, 6:48 pm

SCJ429 wrote:You can get the bolt firing pin hole bushed if you are concerned about it. Was it a Remington action?


+1 or change to a thicker cup primer :lol:
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Re: Twist Rate, Pill Weight and Stability

Post by Gaznazdiak » 24 Oct 2018, 8:37 pm

Virtually new (less than 800 fired) Howa action.

I'm using CCI BR4 now, it might be worth making a couple of 25gn loads with them to see if they are more robust that the Remingtons.
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