Thread: Sierra BC

So those that load sierra longer range bullets, do you just average the published Bc for the various speeds for a start then shoot for validation?
or is there a better way?
Problem is of course there isn't many and one needs to find a load and also check impact is true at distance using the minimum number of bullets.

With Shooter I just enter all the values and velocities.
Or if Litz has published a value I use that instead.

And yes to validation.

considered using Applied Ballistics and you can buy the cdm rather than using the box numbers.
What projectile?

@jakewire

Bryan Litz's book: https://ia800105.us.archive.org/21/i...long_range.pdf

Look up the G7 BC in the Appendix, only based on a 3,000 FPS max velocity but I would trust the values as they are actual results and not calculations.

Might be worth noting that some Sierra projectiles have changed design a bit, but this was done in 2015 so quite recent.

Always validate

If your looking to cut corners, save money or projectiles then long range is not for you

I have 2 boxes of 140gr Sierra TMKs and fuck all powder
don't really want to use most of them fucking about if I don't have to
Thanks for the replies
Validation is what I have always done.

YOU having a bad day or something Andrew @7mmsaum

Run a G7 if boat tail. This prevents the need for a decreasing G1.

As mentioned already, a CDM is the best option, or an independent G7.

Lastly, it's worth mentioning the Turing the MV at around Mach 1.25 should occur BEFORE Turing the BC.

Sent from my SM-G991B using Tapatalk

The idea of the post was to ask if people used an average BC from Sierra Data or had another method when starting the validation.
cheers.

I use the multi bc on strelok pro with the 160tmk.....
Taken it out to 1250meters on papa faces and 725 meters on goats

Just average them or take the middle one, doesn't really make that much difference, will certainly get you in the ball park.

Originally Posted by jakewire

I have 2 boxes of 140gr Sierra TMKs and fuck all powder
don't really want to use most of them fucking about if I don't have to
Thanks for the replies
Validation is what I have always done untill the latest bullshit.

YOU having a bad day or something Andrew @7mmsaum

Load development and/or long range testing is not a task you want to undertake with any kind of process restriction

There is potential to end up with an incomplete experience/results, and at the very least a persistent feeling that you never really validated at all distances required (then that animal you really want appears at the distance you didn’t test at) all because of the desire to save components

It’s one of those jobs that deserves your full effort and there’s a learning curve and familiarisation to enjoy as well

Often when load developments are being carried out the shooter is being developed as well, the trigger time is an excellent way to be schooled.

Your initial question has been answered by previous members, i merely pointed out (with minimal tact) that it’s not wise to do an incomplete job

Yeah i run multi bc for the 107smk. To get it tuned to match my drop i have 4 different bc values from 1km onward. Inside 1000 i use the data strelok pro gives me and their g7 but after that i tuned with multi bc. Came out to be way more efficient, it transitions really well for such a little pill