I use the Wilson seater/arbor press setup and although slow it is consistent. You will still see issues if your neck tension is not consistent, just like with other setups.
Use lowest SD or lowest MOA?
- Thread starter Forrest Mc
- Start date
I use the Wilson seater/arbor press setup and although slow it is consistent. You will still see issues if your neck tension is not consistent, just like with other setups.
800, 900 ,1000
coldboreshot
Silver $$ Contributor
Whoa, just finished reading this entire thread...once again, "borescopes and chronographs should come with psychological disclaimers".
Attachments
CharlieNC
Gold $$ Contributor
SD(target) = SD(velocity) * Harmonic Compensation(at range).
The SD of the shots on the target, and of muzzle velocity are directly measureable. Using a little math and ballistic calculator, the results from a ladder test can be utilized to quantify the harmonic cycle. Attempting to develop a load for velocity SD does not assure the harmonics and consequently target performance are in proper alignment, ultimately the target prevails as the foremost factor.
The SD of the shots on the target, and of muzzle velocity are directly measureable. Using a little math and ballistic calculator, the results from a ladder test can be utilized to quantify the harmonic cycle. Attempting to develop a load for velocity SD does not assure the harmonics and consequently target performance are in proper alignment, ultimately the target prevails as the foremost factor.
Because they are trying to load development at a short distance in order to reduce/eliminate atmospheric variables (wind) but have a load which ought to perform at longer distances?
Of course, if you could eliminate atmospheric conditions and develop loads in a tunnel you could follow Alex and just go for the smallest group at the longest distance you are going to shoot. If you (rightly in my view) dismiss the notion of convergence, absent human error the groups will always be smaller at shorter distances. But not many people have access to really long tunnels.
The other way is to say that a bullet's trajectory is defined the moment it has left the barrel. Ignoring atmospheric influences from round to round which we want to do, each bullet's path is set by its velocity and barrel harmonics at exit. The group produced by a series of rounds at 100 yards can be extrapolated to 200 and beyond. (Of course we hope also for low ES in bullet to bullet drag variance.) If it isn't good at 100 it isn't going to be any better at 200 and beyond.
So load development at shorter distances focuses on achieving the best possible mix of velocity ES/SD and POI ES/SD. One without the other isn't any good and trade-offs are necessary. No one is saying pursue low vel SD/ES in blind ignorance of POI ES/SD. But to look only at short range POI ES/SD without even knowing vel SD/ES is ignoring the fact that an optimal mix of both is required for longer distances. All else being equal, two groups at a 100 with equal POI ES/SD (same group size) but with different vel ES/SD aren't going to look the same at 200 and beyond. A tighter group at 100 with much worse vel SD/ES than another may well be a worse group at longer distances. It requires a good chrono which doesn't introduce significant measurement error.
In essence the debate is whether you believe convergence is possible. If not, develop at shorter distances to reduce atmospheric variables and work towards the best possible mix of both vel and POI ES/SD.
The rubber meets the road the moment the bullet exits the barrel. You aren't chasing after it and giving it a nudge every now and then.
Last edited:
Sixgun
The Millbastard
http://forum.accurateshooter.com/attachments/15540698965884781032252514911870-jpg.1098470/ This is your 800, 900, 1000 yard target?
The last few months I have had the opportunity to tune my hunting rifles at 1k on paper at Deep Creek. Didn’t have my chrono when finalizing load. After it shot small (3”) 3 shot group, then I set up my Labradar and checked it out. ES was 18-20 FPS and had very little vertical for a bipod and rear squeeze bag. The 338 edge shot a 1.25” 3 shot group and had an Es of 18. If I tune a rifle good, I can’t shoot the group small enough that the Es gives me a ton of vertical.
Attachments
If your shooting under 300 yards ES and SD don't mean much. Go for group size, that's what they measure for SR comp. I can shoot groups under .300" with a ES of 35 on my 6BR Varmint rifle.
Oh, Lord no! The red targets are 104 yds. I had referred later to having shot a F-Class match which was 800, 900, 1000. That is what I thought you were asking about.
Yes, I was load developing at 100 yards, the only range available, to work up a load to take to my first long range (800-1000 yards) F-Class match. I think it was beneficial that the load I settled on was in the 3.8 SD range.
Dusty Stevens
Shiner
What distance does it matter on? Ive shot them all and never had to show chronograph numbers
I would have to buy another chronograph as I gave mine away years ago. I do not measure FPS and only shoot one load and then make corrections with a tuner. What am I missing? Always thought the Lab Radar looked like a nice tool.
Ben
You haven’t talked to or verified with enough top level, record holders then!
It may not matter in benchrest because there is less rifle contact but in F Class you can see it.
Dusty Stevens
Shiner
Im sure not going to argue that because my customers that hold records in f class are sponsored and on teams and im not at liberty to say but quite a few f class records stand by target results over chronograph results
We all use target results but chronograph sure helps get it there.
Not at liberty to say what, who your record holding customers are? Why not?
I happen to be a multiple record holding F Class shooter. I have sponsors and a team
Upgrades & Donations
This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.