257 Wby range day - 115 NBT - any feedback?

[Dr. Vette]

I surely understand the limits of my BMC. But considering all loads were shot over the same BMC, in roughly the same conditions, the error should be universal enough to maintain comparability, right? I'm geeking statistics now. Sometimes I think I should have been a math major.

Yes, generally true. However, the angle of the sun changes a lot from 8:30 to 10:30, and that affects the chrony readings. Don't ever try and count on a BMC's readings in direct sunlight - it adds over 100fps to this same rifle in my testing last fall.

 

[SJB358]

I surely understand the limits of my BMC. But considering all loads were shot over the same BMC, in roughly the same conditions, the error should be universal enough to maintain comparability, right? I'm geeking statistics now. Sometimes I think I should have been a math major.

Yes, generally true. However, the angle of the sun changes a lot from 8:30 to 10:30, and that affects the chrony readings. Don't ever try and count on a BMC's readings in direct sunlight - it adds over 100fps to this same rifle in my testing last fall.

I see the same thing. I won't chrony in direct sunlight. Really, I believe one of the Magneto Chrono's is on the my must have list. I hate getting nefarious chrono readings and don't really enjoy setting up chrono's either.

 

[Dr. Vette]

I surely understand the limits of my BMC. But considering all loads were shot over the same BMC, in roughly the same conditions, the error should be universal enough to maintain comparability, right? I'm geeking statistics now. Sometimes I think I should have been a math major.

Yes, generally true. However, the angle of the sun changes a lot from 8:30 to 10:30, and that affects the chrony readings. Don't ever try and count on a BMC's readings in direct sunlight - it adds over 100fps to this same rifle in my testing last fall.

I see the same thing. I won't chrony in direct sunlight. Really, I believe one of the Magneto Chrono's is on the my must have list. I hate getting nefarious chrono readings and don't really enjoy setting up chrono's either.

I got a MagnetoSpeed for Christmas, but many forum posters state that it will affect grouping and load workup. So, the BMC is being used for workup, and I'll use the MagnetoSpeed at the end to verify true speed. That seemed to make the most sense to me.

 

[rodell]

I shoot to find my group, then use my magnetospeed to get the data I need for my ballistic chart. I don't worry too much about fps spread if the load is doing what I want.

It definitely will affect your POI, but not by a lot. Still, it is a variable you don't need to have in the equation.

 

[bobnob]

Dr Vette, just a thought from a self proclaimed amateur, but for my money I would be shooting a handful of 5 shot groups with that 68.0g load and seeing what happens. One ok group of three shots doesn't tell you much. The 68g group looks the best to me and I'd be seeing if it can do that a little more consistently, THEN tinkering with the oal and so on.

I also recommend shooting the groups in collectives of the same charge weight rather than round robin. Its probably my sloppy technique, but I find my groups are a lot tighter when I don't change anything at all between shots. To that end for a 3 shot group I will generally shoot all 3 in under 3 minutes without getting up from the bench and I seem to group them a lot better.

Sorry because I know some of this is basic stuff and you probably don't need reminding. I hope it might have been of some small help.

- Bob

 

[HOGWILD338-378]

I would try RL25 with 68.0 gr and work up to 70 gr, maybe that rifle just does not like that powder bullet combo? I have heard where some UL's were finicky finding loads for them! Maybe try some RL 25 with 120 gr Partition's with A near max charge outta Noslers load book! That rifle just might not like that combo you are using?