Varminterror
New member
Random thoughts here, since there's already so much valuable information being shared...
First off, the difference between the two won't matter enough to say one is favorable over the other. Way too many subjective attributes come into play here that the difference on paper won't really matter. Guys will make the same statements about a .300wm or wsm or wby over a .308 win or .30-06, but we all know you can kill whatever you want at a [beeep] long poke with the "lil" .308win...
Now on with the show...
If we're talking extreme long range, where the difference in windage and drop will actually be substantial between these two, then you're not really talking about 75-87grn pills usually. At that point you're already going to be looking at heavier, higher BC pills to get the most out of your case. Talking about comparing 75-87grn 6mm and quarter bore loads at 800yrds, in my humble opinion, is kinda like talking about whether a 4cylinder or a 6banger would do better in the Daytona 500. Neither are really a great choice. Considering that, my mindset is you should be looking at heavier bullets.
Directly comparing a .25WSSM and a .243WSSM, the .25WSSM wins, so it's not fair to say that you'll REALLY be comparing the same MV with the same bullet weight.
You actually do have more powder capacity in the .25WSSM, especially when considering magazine restrictions. For the same bullet weight, a heavy for cal 6mm will be longer than a 25, which gives it a better BC, but means it has to be seated deeper to fit in your mag. For 75-87grn pills, probably not an issue, especially if you're talking bolt gun, not AR platform, but if you're honestly talking long range shooting, see note above about shooting heavier pills, in which case COAL becomes more relevant. THEN consider you're losing a bit of capacity in the 6mm WSSM over the 25WSSM for the smaller neck/shoulder, and you start seeing better performance out the 25WSSM simply from higher case capacity. With a lighter-for-cal bullet, you can seat the longer 6mm bullets a little longer out and try to make up some case capacity, but from what I've seen of the two so far, the 25WSSM holds more powder in most loads.
Equally, comparing the .25-06 and the .243, you have a lot more room under the '06 than the .243, which can be pretty meaningful.
Also, since both are loaded to roughly the same pressure, you'll end up getting more power out of a quarter bore than you would out of a 6mm barrel, that's simple physics. At the same pressure, the larger bore will always win.
Sure, if you say that both cases put a 75grn pill at the same MV, then the smaller bore will have the better BC, giving it a bit less drop and drift downrange. Is that drop difference meaningful? Eh, hard telling, my opinion is probably not. BUT, again, that's assuming you really get the same MV with the same bullet weight out of both cases, but again, I don't think it's fair to say that. The Quarter WSSM will be faster for the same bullet weight than the 6mm WSSM. Basically same rules apply for the .25-06 and .243win.
First off, the difference between the two won't matter enough to say one is favorable over the other. Way too many subjective attributes come into play here that the difference on paper won't really matter. Guys will make the same statements about a .300wm or wsm or wby over a .308 win or .30-06, but we all know you can kill whatever you want at a [beeep] long poke with the "lil" .308win...
Now on with the show...
If we're talking extreme long range, where the difference in windage and drop will actually be substantial between these two, then you're not really talking about 75-87grn pills usually. At that point you're already going to be looking at heavier, higher BC pills to get the most out of your case. Talking about comparing 75-87grn 6mm and quarter bore loads at 800yrds, in my humble opinion, is kinda like talking about whether a 4cylinder or a 6banger would do better in the Daytona 500. Neither are really a great choice. Considering that, my mindset is you should be looking at heavier bullets.
Directly comparing a .25WSSM and a .243WSSM, the .25WSSM wins, so it's not fair to say that you'll REALLY be comparing the same MV with the same bullet weight.
You actually do have more powder capacity in the .25WSSM, especially when considering magazine restrictions. For the same bullet weight, a heavy for cal 6mm will be longer than a 25, which gives it a better BC, but means it has to be seated deeper to fit in your mag. For 75-87grn pills, probably not an issue, especially if you're talking bolt gun, not AR platform, but if you're honestly talking long range shooting, see note above about shooting heavier pills, in which case COAL becomes more relevant. THEN consider you're losing a bit of capacity in the 6mm WSSM over the 25WSSM for the smaller neck/shoulder, and you start seeing better performance out the 25WSSM simply from higher case capacity. With a lighter-for-cal bullet, you can seat the longer 6mm bullets a little longer out and try to make up some case capacity, but from what I've seen of the two so far, the 25WSSM holds more powder in most loads.
Equally, comparing the .25-06 and the .243, you have a lot more room under the '06 than the .243, which can be pretty meaningful.
Also, since both are loaded to roughly the same pressure, you'll end up getting more power out of a quarter bore than you would out of a 6mm barrel, that's simple physics. At the same pressure, the larger bore will always win.
Sure, if you say that both cases put a 75grn pill at the same MV, then the smaller bore will have the better BC, giving it a bit less drop and drift downrange. Is that drop difference meaningful? Eh, hard telling, my opinion is probably not. BUT, again, that's assuming you really get the same MV with the same bullet weight out of both cases, but again, I don't think it's fair to say that. The Quarter WSSM will be faster for the same bullet weight than the 6mm WSSM. Basically same rules apply for the .25-06 and .243win.
