Re: 7 wsm vs 7 rsaum that is the ?
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.25AOD,
I dont mean to flame you on your two posts, but you could not be more wrong if you went out of your way to try.
The longer throat is exactly what gives this round its added velocity.
In my opinion the problem with WSM and SAUM is that the SAAMI spec O.A.L. is very short so your bullet is taking up a great deal of powder capacity, with the chambering that fiftydriver did for me the bullet is not taking up any powder capacity because it is in only the neck. the SAAMI spec O.A.L for a 7WSM is 2.860" the O.A.L. for my chambering is 3.230 making a difference of .370" if you add in bullet diameter of .284" ,that is a lot of powder capacity. I will let some mathematical genius figure out how much.
UB
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Area of a cylinder= 3.1416 (pi) x radius squared( .284" divided by 2) X length (.370")
A=3.1416 x (.142 x .142) x .370
A= 3.1416 x .02016 x .370
A= .02343 cubic inches ( not accounting for the boat tail which reduces the area......in other words, a boat tail bullet doesn't displace as much powder capacity as a flat base bullet).....
If bore size, bullet weight and pressure are constant, potential velocity increase varies at one fourth the percentage change of the case capacity.
To precisely figure the potential velocity increase, we would need the capacity of the WSM case with the bullet seated at 2.860" and at 3.23".....
However, we can do some rough calculations and gain some insight......if you divide the base velocity (let's say 3000 fps) by the reported velocity increase (150 fps), you get .05% velocity increase......plug that into the formula and we can determine that, with everything else being equal, you would need to increase the case capacity by 20% to achieve the 150fps increase in velocity......does seating your bullet out an additional .37" results in a 20% increase in case capacity?? If not, then your velocity increase can't be credited solely to the longer OAL.......
