MUZZLE VELOCITY VS. GRAINS OF POWDER

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Last Post 12 July 2018

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joeb33050 posted this 04 July 2018

The relationship is linear.

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joeb33050 posted this 04 July 2018

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joeb33050 posted this 04 July 2018

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joeb33050 posted this 04 July 2018

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Ross Smith posted this 05 July 2018

Joe: If a powder such as black powder were used where an overcharge in a "strong" firearm would be difficult to achieve, wouldn't a point of diminishing returns be found? In muzzleloaders, ever increasing powder charges usually end up blowing unburnt powder on the ground and barrel length can become the limiting factor.. I respect the point that we could go to extremes and just blow things up. I'm not wanting to overcharge anything.

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JeffinNZ posted this 05 July 2018

Remarkably linear Joe. Nice.

With BP the over charge ends up igniting beyond the muzzle blinding and deafening the operator.

Cheers from New Zealand

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joeb33050 posted this 05 July 2018

I suspect that the relationship becomes non-linear beyond both 5.5 and 8.5 grains, but don't know.. I've seen no signs of pressure at 8.5 gr. All cases have a light coat/smear of oil, else case headspace increases-sometimes-some cases.

From this data I think I can write the relationships between MV and barrel length, (The M12 Old bbl. is 26" long, the Stevens bbl. is 22" long.); and between MV and ctg. size-223 vs. 22-250.

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Ross Smith posted this 05 July 2018

Thanks Joe.

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TRKakaCatWhisperer posted this 06 July 2018

As further study, I'd like to see the relationship between powder weight, velocity, pressure, AND accuracy.

I've seen a fellow doing it in the development of loads for the 50 Beowolf. (yes, that was a few years ago)

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joeb33050 posted this 07 July 2018

As further study, I'd like to see the relationship between powder weight, velocity, pressure, AND accuracy.

I've seen a fellow doing it in the development of loads for the 50 Beowolf. (yes, that was a few years ago)

There are many data pieces needed; help is needed. Man(or woman), gun, loads and chronograph needed. Simple 50 shot tests. Interested?

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TRKakaCatWhisperer posted this 08 July 2018

It takes more - a method of determining pressure. There was one old chrono that did it as well as measuring velocity. Don't know of what's out there now that would do it. It would be interesting to see the relationship between pressure, accuracy, velocity, and alloy.

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beagle6 posted this 12 July 2018

According to Vihtavuori Powder Company, a change of 10% in powder charge will change velocity 8% and pressure 20%.

A change in bullet weight of +10% will drop MV by 4% and raise pressure by 8%.

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joeb33050 posted this 12 July 2018

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joeb33050 posted this 12 July 2018

Here is the data for 2 bbls, 3 bullet weights, 22-250, Titegroup..

Top left value, .853, is (INCREASE IN MV, % / INCREASE IN POWDER CHARGE, %).

Increase the charge 1%, MV increases .853 X 1% = .853%, 10% charge increase gets an 8.53% change in MV.

The bottom row and right hand column are averages.

The average for the whole is .686.

The 223 22-=250 bbl is 16.5" long, Shilen = 26" long. The ratio clearly varies with bbl. length. Ratio also varies with powder charge and bullet weight.

The published 8% looks high.

joe b.