Fiftydriver
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To be honest, I was really not familiar with this bullet but noticed it the other day and did some looking into it. I understand why we are going with the 140-142 gr class bullets for the larger 6.5mm but I am actually suprised I have not heard more about this bullet.
Sierra is advertising a BC of 0.510 compared to 0.595 for their 142 gr MK. In chamberings like the 6.5mm BR adn up to the 6.5-06 AI, from all the data I can dig up which is not all that much, the lighter 123 gr SMK can be driven from 250 to 300 fps faster then the 142 gr.
Now, in my opinion, a round such as the 6.5x47 Lapua or the 260 Rem is a sub 800 yard chambering. Now, I know it will reach out alot farther then that but at 800 yards, retained energy and velocity is getting pretty low to do anything but punch paper so I personally feel for hunting this is the max limit to this type of chambering.
Just for comparision however, lets look at the 260 Rem loaded with the 123 gr SMK at 3100 fps and the 142 gr loaded to 2850 fps. These are pretty hot numbers and would need long barrels to get it but this is pretty standard for the velocity spread of these bullet weights in this class of chambering from what I can find.
Lets look at drop numbers, not really important but just a way to compare the two, all with 100 yard zero.
123 gr SMK
500 yards...............-39.7"
750 yards...............-114.6"
1000 yards.............-245.7"
142 gr SMK
500 yard.................-46.8"
750 yards...............-132.4"
1000 yards.............-279.4"
Pretty impressive for the little bullet. I know I just said the 260 is not a +800 yard rifle but these numbers are just for comparision or for paper punching.
Now lets look at wind drift with a 10 mph full value wind. The big 142 gr bullet should really stop the lighter bullet. not really.
123 gr SMK
500.........................13.4"
750.........................32.4"
1000.......................62.5"
142 gr SMK
500.........................13.0"
750.........................31.5"
1000.......................60.9"
Within 1.5" drift out to a full 1000 yards.
Now I know that I have always been a proponant of heavy for caliber bullets for long range shooting and that has not changed. Espeically for large capacity chamberings that have the horsepower to drive the heavy bullets to high velocity but for those smaller chamberings, I see no real disadvantage to using the lighter bullets in place of the 142 gr SMK and actually have some advantages.
Namely, less recoil and less rifle torquing.
Now I am not saying the heavier 140 to 142 gr bullets are not completely at home in these smaller cartridges, my only question is why do we not see more use of this 123 gr SMK in the smaller calibers where it seems more at home with much better velocity potential.
It is my opinion that its best to get 3000 fps for a long range chambering if at all possible, this bullet would allow the likes of the 260 Rem, 6.5x 47 Lapua and the like to accomplish this and do so with a bullet with a pretty impressive BC.
Just wondering your thoughts. By the way, I have 1000 of these headed my way to test out. I think it may also be a real screamer in my 6.5mm WSM. We will see.
Sierra is advertising a BC of 0.510 compared to 0.595 for their 142 gr MK. In chamberings like the 6.5mm BR adn up to the 6.5-06 AI, from all the data I can dig up which is not all that much, the lighter 123 gr SMK can be driven from 250 to 300 fps faster then the 142 gr.
Now, in my opinion, a round such as the 6.5x47 Lapua or the 260 Rem is a sub 800 yard chambering. Now, I know it will reach out alot farther then that but at 800 yards, retained energy and velocity is getting pretty low to do anything but punch paper so I personally feel for hunting this is the max limit to this type of chambering.
Just for comparision however, lets look at the 260 Rem loaded with the 123 gr SMK at 3100 fps and the 142 gr loaded to 2850 fps. These are pretty hot numbers and would need long barrels to get it but this is pretty standard for the velocity spread of these bullet weights in this class of chambering from what I can find.
Lets look at drop numbers, not really important but just a way to compare the two, all with 100 yard zero.
123 gr SMK
500 yards...............-39.7"
750 yards...............-114.6"
1000 yards.............-245.7"
142 gr SMK
500 yard.................-46.8"
750 yards...............-132.4"
1000 yards.............-279.4"
Pretty impressive for the little bullet. I know I just said the 260 is not a +800 yard rifle but these numbers are just for comparision or for paper punching.
Now lets look at wind drift with a 10 mph full value wind. The big 142 gr bullet should really stop the lighter bullet. not really.
123 gr SMK
500.........................13.4"
750.........................32.4"
1000.......................62.5"
142 gr SMK
500.........................13.0"
750.........................31.5"
1000.......................60.9"
Within 1.5" drift out to a full 1000 yards.
Now I know that I have always been a proponant of heavy for caliber bullets for long range shooting and that has not changed. Espeically for large capacity chamberings that have the horsepower to drive the heavy bullets to high velocity but for those smaller chamberings, I see no real disadvantage to using the lighter bullets in place of the 142 gr SMK and actually have some advantages.
Namely, less recoil and less rifle torquing.
Now I am not saying the heavier 140 to 142 gr bullets are not completely at home in these smaller cartridges, my only question is why do we not see more use of this 123 gr SMK in the smaller calibers where it seems more at home with much better velocity potential.
It is my opinion that its best to get 3000 fps for a long range chambering if at all possible, this bullet would allow the likes of the 260 Rem, 6.5x 47 Lapua and the like to accomplish this and do so with a bullet with a pretty impressive BC.
Just wondering your thoughts. By the way, I have 1000 of these headed my way to test out. I think it may also be a real screamer in my 6.5mm WSM. We will see.
