Range Report Need help interpreting my first Chrono results

[PaC1776]

.308 Win 175gr SMK, Varget, CCI 200, Win brass, Savage 10FCP-SR.

I don't particularly see a flat spot in this batch.
Started to see a minor ejector mark at the 44.5-45gr load. Primers looked fine.

41gr
Min 2435 1- 2435
Max 2458 2- 2457
Avg 2449 3- 2458
SD 10.7 4- 2446
ES 23 5- missing

41.5
Min 2461 1- 2487
Max 2487 2-2462
Avg 2470 3- 2471
SD 10.3 4- 2470
ES 26 5- 2461

42gr
Min 2497 1- 2521
Max 2521 2- 2497
Avg 2505 3- 2501
SD 9.6 4-2509
ES 24 5-2500

42.5
Min 2516 1- 2527
Max 2533 2- 2516
Avg 2526 3- 2533
SD 6.6 4- 2524
ES 17 5- 2531

43gr
Min 2551 1- 2556
Max 2558 2- 2555
Avg 2555 3-2551
SD 2.8 4- 2558
ES 7 5-2558

43.5gr
Min 2579 1- 2596
Max 2596 2- 2579
Avg 2586 3-2579
SD 7.8 4- 2585
ES 17 5- 2593

44gr
Min 2610 1- 2617
Max 2632 2- 2632
Avg 2617 3- 2615
SD 8.4 4- 2614
ES 22 5- 2610

44.5gr
Min 2635 1- 2643
Max 2661 2- 2661
Avg 2646 3- 2635
SD 9.4 4- 2645
ES 26 5- 2646

45gr
Min 2674 1- 2684
Max 2702 2- 2674
Avg 2683 3- 2677
SD 11.0 4- 2702
ES 28 5- 2680​

 

[Holliday]

I get similar results. Not getting The whole “flat-spot” thing. Perhaps smaller increments?

 

[Jefe's Dope]

I'm as new as you or newer but I'm assuming this is what you're looking for.

43.5gr
Min 2579 1- 2596
Max 2596 2- 2579
Avg 2586 3-2579
SD 7.8 4- 2585
ES 17 5- 2593

SD/Standard Deviation of 7.8 FPS and an ES/Extreme Spreed of only 17 seems pretty ideal. Again, I'm a noob and could be misunderstanding.

 

[Holliday]

I'm as new as you or newer but I'm assuming this is what you're looking for.

43.5gr
Min 2579 1- 2596
Max 2596 2- 2579
Avg 2586 3-2579
SD 7.8 4- 2585
ES 17 5- 2593

SD/Standard Deviation of 7.8 FPS and an ES/Extreme Spreed of only 17 seems pretty ideal. Again, I'm a noob and could be misunderstanding.

That “flat-spot” refers to a series of loads, where velocity jumps less than in other areas. A lot of people swear by that method because purportedly you maintain accuracy with temperature shifts up and down. That is if you choose the middle of the flat spot.

 

[3-0-hate]

I'm as new as you or newer but I'm assuming this is what you're looking for.

43.5gr
Min 2579 1- 2596
Max 2596 2- 2579
Avg 2586 3-2579
SD 7.8 4- 2585
ES 17 5- 2593

SD/Standard Deviation of 7.8 FPS and an ES/Extreme Spreed of only 17 seems pretty ideal. Again, I'm a noob and could be misunderstanding.

His load of 43 has better ES and SD. ~30 less FPS though.

43gr
Min 2551 1- 2556
Max 2558 2- 2555
Avg 2555 3-2551
SD 2.8 4- 2558
ES 7 5-2558

Either would work. I would be looking at the target downrange and see how each of these loads print. If the faster load gives groups just as good as the slower load, I would stick with the faster one personally. All depends on the application. If hes shooting NRA Hi-Power with an M1a, I would have no issue with the slower load.

 

[tnichols]

Agreed ^^^ The 43 load is in the ballpark. I’d work just a touch either side of that and call it good. Without knowing temp and barrel length, it’s the best choice with the data given.

 

[PaC1776]

Agreed ^^^ The 43 load is in the ballpark. I’d work just a touch either side of that and call it good. Without knowing temp and barrel length, it’s the best choice with the data given.

76F and 20" barrel

 

[Jefe's Dope]

His load of 43 has better ES and SD. ~30 less FPS though.

43gr
Min 2551 1- 2556
Max 2558 2- 2555
Avg 2555 3-2551
SD 2.8 4- 2558
ES 7 5-2558

Either would work. I would be looking at the target downrange and see how each of these loads print. If the faster load gives groups just as good as the slower load, I would stick with the faster one personally. All depends on the application. If hes shooting NRA Hi-Power with an M1a, I would have no issue with the slower load.

Doh! I don't know how I missed that. Much better than 43.5.

 

[tnichols]

76F and 20" barrel

That’s certainly in the ballpark for barrel length and maybe a tiny bit on the slow side, but, low SD’s are your friend at distance.

 

[DrainTheSwamp2017]

https://www.snipershide.com/shooting/threads/magneto-speed-and-accuracy.6869554/#post-6901351

Check this thread out.
Lot of good info. I just did my first ocw using magnetospeed and had a lot of help interpreting my results. I did the work and they told me where to investigate and posted my results.
I’ve found it helps to graph everything thing out in a line graph and list sd/es/averages, little easier to analyze that way.
Someone smarter than me can help pretty easily after that. Took me 57 rounds to find my sweet spot.

 

[CharlieNC]

Did the target give you the desired flat spot? I believe in barrel harmonics, positive compensation, which yield this. I would never use the chrono over the target to make a load choice.

 

[ultrarunner7]

.2 or .3 grain increments man. You'll see it

 

[Mikemo]

Yup, your increments are too big. Use 0.2g

 

[DrainTheSwamp2017]

I like .5 gr increments to find max charge, desired velocity, and sometimes a flat spot(not so steap velocity jump) after you find those I d break it down into smaller increments as well, and shoot a 3-5 shot string for each charge

 

[Jimgal62]

76F and 20" barrel

My AXMC 308 WIN, 20” , 1:10 Twist, likes 42.3 grains with a MV of 2700 FPS.

 

[PaC1776]

My AXMC 308 WIN, 20” , 1:10 Twist, likes 42.3 grains with a MV of 2700 FPS.

42.3 of what?

I'm only getting about 2500fps with varget.