*updated JULY27* Chrono results round 2! Observations on caldwell chronograph in varying lighting *updated*

[Hoody2shoes]

I ran my 12.5 criterion through a labradar about a week and a half ago and got an average of around 2625fps with mk262's. Temp was around 88° and about 35% humidity, around noon with steady amounts of full sun. I proceeded to put the new average into strelok and tested out the estimated holds at 400, which proved to be dead on.

That number still seemed high so I ordered a caldwell just to confirm. I've never used a caldwell before so I played with it at varying heights and shot angles to see what affect it had on the velocity readings. The first strings were unsuppressed


6/14 72° mk262 55% humidity, 1630-1830, distance about 12'

Low height varying angles, no sunshade, no clouds
2645 slight down
2634 level
2653 slight down
2596 slight up
2675 very down
Avg 2640

Low height, varying angles, no sunshde, no clouds
2590 slight up
2612 level
2579 up
2646 slight down
2613 level
Avg 2608

Mid height, consistent angle, varying sun, no sunshade
2590 clouds creating shade during shot
2611 same clouds, consistent light
2586 slight up, same clouds
2613 level same clouds
2630 level, no clouds
Avg 2606

Mid height, level angle, varying light, no sunshade
2633 no clouds
2611 slight clouds
2577 cloudy
2640 no clouds
No data
Avg 2615


Suppressor
Mid height, no clouds
2647 level
2634 slight up
2641 level
2669 slight down
Avg 2647

2601 up
2640 level
2652 level
2654 level
2637 level
Avg 2636

Unsuppressed
Mid height, Changing lighting conditions, no sunshade
2595 level with clouds setting in
2647 level with clouds leaving
2658 level with full sun, clouds leaving
2640 level with full sun (fired quickly)
2601 level with clouds setting in
Avg 2628

High height, varying lightening, all level, no sunshade
2579 heavy cloud setting in
2634 no clouds
2632 no clouds
2626 no clouds
2618 light clouds
Avg 2615

Mid height, rapidly changing clouds, level shots, no sunshade
2617 clouds leaving
2596 clouds setting
2586 clouds consistent
2622 clouds leaving
2623 full sun
Avg 2608

High height, slight up angle, rapidly changing clouds, no sunshade
2606 clouds leaving
2580 consistent lighting
2572 clouds setting in
2580 consistent lighting
2613 clouds leaving into full sun
Avg 2590

High height, consistent sun, upward angles, no sunshade
2605 slight up
2575 up
2585 up
2607 slight up
2595 slight up
Avg 2593

High height, consistent clouds, level shots, sunshade
2590
2592
2589
2583
2649 clouds leaving
Avg 2600

Mid height, level shots, consistent clouds, no sunshade
2596
2605
2600
2604
No data
Avg 2601

Mid height, level shots, changing clouds, sunshade
2609 consistent
2577 clouds enter
2641 full sun
2610 slight clouds
2630 full sun
Avg 2613

Mid height, level shots, mostly consistent sun, no sunshade
2614 full sun
2629 full sun
2615 full sun
2608 slight cloud
2649 clouds leaving into full sun
Avg 2623

Notes on the caldwell:
-shot angle greatly affects velocity readings
-height of chronograph played no role in velocity readings
-the sunshade showed no difference in reading in full sun, but read lower in cloudy conditions
-Lower light levels read as lower velocities in all setups
-during changing conditions, there was more variation in readings. When getting darker, the first shot would read lower, and the next shot with the same conditions would read higher. Conversely, when it got brighter the shot would read High, with the next shot "settling in" at a lower reading. If given time to adjust to light level, there was much less variation

After this was over I went to the KD range and hit the 240y 8" gong using my strelok holds, with the velocity set at 2625. Still dead on.

 

[ARShooter91]

You shoot all that mk262 into the dirt for this testing?

 

[Hoody2shoes]

@ARShooter91
I did! I have a good supply of it...

Today only totalled 100 rounds anyway

 

[hlee]

Orrrrr, after 100 rounds fired across the chronograph, you have a much better estimate of your true SD and ES…

 

[Hoody2shoes]

@hlee I'm not sure whom/what that is directed at.

 

[BCP]

Mk262 went 2800+ out of a 20" that I had so 2500-2600 out of a short barrel would make sense. You try taking one apart to see how much powder is in it? People used to say TAC powder, then it was 8208, now it might be one of the 2000MR type powders.

 

[Hoody2shoes]

@BCP I have not taken one apart, and if I did I wouldn't even know what to look for. I know nothing about reloading/powders though I do understand the principles of how different powders behave.

 

[Hoody2shoes]

I averaged my leveled shots in good, consistent lighting conditions and got 2624

 

[BCP]

@BCP I have not taken one apart, and if I did I wouldn't even know what to look for. I know nothing about reloading/powders though I do understand the principles of how different powders behave.

Its probably a ball powder, St Marks was making a bunch of high energy stuff (superformance type stuff) like 2000MR and I think CFE223 which gives great velocities compared to other powders (one of their powder testers used to post on here). For a long time people would try to take mk262 apart to duplicate it but unless you can crimp your primers it's hard to get the same velocities without popping a primer here and there. The most reasonable one I came up with was 2.245" 77nosler LC brass 24.3 TAC for about 2700-2750 in my 18".

 

[Hoody2shoes]

11.5" core
Sup arms piston kit
88⁰
Humid af
Mk262's right around 2550

This is also fast for an 11.5

 

[Hoody2shoes]

Today's results
77⁰ 70% humidity
Windy with rapidly changing cloud/lighting conditions. Tons of errors. Had to use my judgement a bit today.

12.5 core
Mk262 2626 no can, 2642 with can

Black hills 69tmk 2703 no can, 2712 with can

 

[Baron23]

Ah....friend, I'm easily confused. If this is true,

put the new average into strelok and tested out the estimated holds at 400, which proved to be dead on.

Then WTF are you thinking that the

number still seemed high

There is no better validation than the target.

 

[Hoody2shoes]

Ah....friend, I'm easily confused. If this is true,

Then WTF are you thinking that the

There is no better validation than the target.

You're right. It was more of out of disbelief than anything.

 

[Happiness Is A Warm Gun]

Thanks for taking the time to pass on this info. I always like seeing the actual data for stuff like this.

 

[Hoody2shoes]

Friends rifle

11.5 core
Sup arms piston kit
90⁰
Humid AF

He wanted to test federal fusion MSR

Avg vel 2651
Avg group 1.81

Yet another load that is reporting velocities much higher than normal