09-02-2017, 08:42 PM
I put a grid overlay onto a copy/paste of the picture into my little graphics program. Now this is 600 wide by 975 tall grid, I'll call them pixels, they're not inches or mm, and I had to make a couple assumptions:
1. Measuring the band-gap (grooves) entails going from the outer edge of a band-cut, across both chamfers to the other outer edge.
2. The two bullets look to have the same linear length from ogive to start of the respective boat tail, so I'm assuming that.
Meaning the difference in bearing surface, if any, would be the delta of the band-gap sums.
For the 120 TTSX, I measured a total of the band-gaps (grooves) of 120 pixels, 40 pixels for each gap.
For the MKZ, I measured 100 pixels, well: 1 at 51 and the 2d at 47 so I rounded up slightly, conservatively.
Meaning to me the MKZ may have a bit more bearing surface. Of course the friction is also a function of the hardness + any lubricity of the two metal surfaces, which could be different in the 1 vs the other.
Both are solids not lead/copper so probably uniform hardness properties radially through a bullet's diameter.
So --- hard to say IME - maybe the MKZ is a bit longer of a bearing surface,
But Rick you had the real things not just a picture, so what I'm seeing could be less precise.
O, one more point - rather a question, since the MKZ gaps are further to the rear of the bullet, does that cause more initial friction for the first few microseconds for bullet travel vs the TTSX bands which allow some yielding "sooner" in bullet flight? I wonder but don't know.
Interesting.
1. Measuring the band-gap (grooves) entails going from the outer edge of a band-cut, across both chamfers to the other outer edge.
2. The two bullets look to have the same linear length from ogive to start of the respective boat tail, so I'm assuming that.
Meaning the difference in bearing surface, if any, would be the delta of the band-gap sums.
For the 120 TTSX, I measured a total of the band-gaps (grooves) of 120 pixels, 40 pixels for each gap.
For the MKZ, I measured 100 pixels, well: 1 at 51 and the 2d at 47 so I rounded up slightly, conservatively.
Meaning to me the MKZ may have a bit more bearing surface. Of course the friction is also a function of the hardness + any lubricity of the two metal surfaces, which could be different in the 1 vs the other.
Both are solids not lead/copper so probably uniform hardness properties radially through a bullet's diameter.
So --- hard to say IME - maybe the MKZ is a bit longer of a bearing surface,
But Rick you had the real things not just a picture, so what I'm seeing could be less precise.
O, one more point - rather a question, since the MKZ gaps are further to the rear of the bullet, does that cause more initial friction for the first few microseconds for bullet travel vs the TTSX bands which allow some yielding "sooner" in bullet flight? I wonder but don't know.
Interesting.