Case weights 7x57

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  • Last Post 03 June 2023
Wilderness posted this 14 May 2023

A friend has a nice Brno 7x57 for which he is beginning reloading - jacketed for now.

His load so far is Speer 160 gn HotCor with 39.5 gns Reloder 17. Speer lists 44 max with WInchester brass.

My friend's brass is nny (PPU). I suspect that the nny brass will be of lesser volume than Winchester, revealed in the first instance by case weight.

The basis of my suspicion on nny is the variation I find in .30-30 brass - less than 130 gns unprimed for Remington, about 140 gns for PPU & Starline, and in between for PMC, Winchester and Federal in that order. With my cast bullet loads I found a velocity difference of 50-100 fps between the extremes.

My request is simple - can someone with some Winchester 7x57 brass please weigh a few (unprimed) and post the numbers. I have asked my friend to send me the weight on the nny, so can compare in a future post.

Yes, I know - just use the chronograph, load to approach the velocity as per the data with all the same components (except brass), and case weight be damned. Unfortunately my friend is 500 miles away and does not have his own chronograph.

Sorry for the non CB topic, but too good an opportunity to tap into information.

Edit:

Thanks Admiral - that establishes the relativity of Remington and Winchester cases.

 

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RicinYakima posted this 15 May 2023

It is a good post. Once he gets tired of paying for jacketed bullets, or wants to shoot more, you can lead him down the rabbit hole to cast bullets!!

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Wilderness posted this 15 May 2023

Thanks Rick - he's already there with .30-30. Mixes in some HP cast bullets with the jacketed, and uses .32-20 cast bullets subsonic (Red Dot powder) for our Lever Action competition.

We also used the light stuff for finishers. On one of our trips away, at the end of the week we used up our leftover finishers on the cane toads (a noxious introduction from Hawaii) around camp. Couldn't do it earlier or we'd have stunk the camp out. Properly hit they went about three feet into the air.

Another night my mate just about evaporated a feral cat with a full power soft hollow point cast .30-30.

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admiral posted this 15 May 2023

I can give you case volumes measured with water:

R-P fired case = 58.5gr.

W-W fired case = 62.5gr.

Fired from my Winchester M70 XTR Featherweight 

 

 

 

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JeffinNZ posted this 15 May 2023

It is a good post. Once he gets tired of paying for jacketed bullets, or wants to shoot more, you can lead him down the rabbit hole to cast bullets!!

Temptation thy name is Ric. :-)

Cheers from New Zealand

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Wilderness posted this 03 June 2023

Well, that question must have been beyond the collective experience, though I did eventually get the information from elsewhere.

The weight of the nny cases, for which data is to be interpolated, is 165 gns unprimed.

The weight I now have for some Winchester cases is 159 gns unprimed. The Speer data was established with Winchester cases.

Using the old .308 “rule” of "one grain less powder per 7-10 gns extra case weight" would suggest reinterpreting the Speer maximum of 44 gns as more like 43 to 43.5 with nny cases, plus the usual proviso of working up the load. Checking the case weights has probably been useful. A chronograph in my friend's hands would be even more useful.

Thanks to all for your interest.

 

 

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