Help with magnetospeed numbers

[Shiyfire]

Playing with my new magnetospeed and ran some test loads from my Remington xcr 223 with varget and 75 hdy. Numbers are SD/ES/ velocity / powder charge.This was 4 shots each.
Which is the best charge to go with if accuracy is about the same with all.

 

[jepp2]

This was 4 shots each

Any less than 5 shots in a string I have little confidence in for ES & SD. I really like 10 shots before I start having much confidence in the numbers.

 

[Shiyfire]

Its not a benchrest rig ,just long range steel targets

 

[chkunz]

I agree with jeep2. With your 4 shots they are all the same. It will take 10 shots to see any difference and multiple ten shot groups to confirm a winner. One good four or five shot group does not tell you much, one bad 5 shot group tells you more.

 

[PatMiles]

Its not a benchrest rig ,just long range steel targets

Yes it's not a benchrest rig, yes you are going to shoot long range steel, so why not try for the best accuracy possible within reason. You bought the gun to shoot, so shoot some 10 strings and see which load gives you the best , consistent ES and SD numbers. You bought a MagnetoSpeed...use it to YOUR advantage.

 

[Delfuego]

Shoot your groups, pick the best, chrono the load and shoot at 500y for vertical. If it still holds, then go have fun. I shot a national match last weekend after developing a 100y load and shooting 4 with the magnetospeed. Don't overthink it

 

[cfreeman]

24.5 with a 75 is a known good load in most .223s. You may go a little higher and find an even better node. Those Remingtons usually have long throats so you should be able to seat them out pretty far. I’ve shot 24.5 a lot at 200, 300, and 600 with good results.

 

[Ned Ludd]

You've reversed up ES and SD, I believe the order should be SD/ES as you have shown it above. Nonetheless, extremes spreads in the mid/upper teens to low 20s are about the best I can usually obtain with heavy bullets in the .223. Your loads at 24.0 and 24.5 are getting pretty close to that. Personally, I find 0.5 gr increments much to large for the small .223 case, so I would recommend another test from let's say something like 23.9 to 24.5 gr in 0.2 gr increments, or even 24.0 through 24.5 in 0.1 gr increments. The idea is to define the optimal window and load to the middle of it, rather than possibly being at one edge or the other as you might be if you simply chose either 24.0 or 24.5 gr.

 

[Davey Boy]

Isn't 24.5 Varget a tad high for the 75 hornady. Quickload puts it at about 17,000psi over the max limit unless I am making a mistake somewhere. Ql puts mv at 2972fps.

 

[SGK]

Stats calculator so you can figure out your confidence level easily:

https://www.autotrickler.com/stats-calculator.html

Target sample is also only as good as it's statistically confidence. 4 shots = rather low confidence that what you see in your Magnetospeed and on paper is truly representative of behaviour. Muzzle velocity one part of the equation...

The Magnetospeed also has a relatively high degree of error blurring confidence levels further.

 

[Delfuego]

The Magnetospeed also has a relatively high degree of error blurring confidence levels further.

I am going to stop this right here. Magnetospeed is accurate and has been tested against every other chrono out there. It works as advertised, period.

 

[Ned Ludd]

I am going to stop this right here. Magnetospeed is accurate and has been tested against every other chrono out there. It works as advertised, period.

^^^This. Used one for years. It is no less accurate than many other commonly-used chronographs. Unlike the LabRadar I'm currently using, the MagnetoSpeed virtually never failed to obtain a reading. It is a very, very good piece of kit. As far as confidence, even a single shot chronograph reading is far better than none at all in terms of predicting drops. The value of running huge numbers of shots per string over a chronograph is highly overrated. Shoot 4 shots, record the Avg/ES/SD, then shoot 6 more or even 16 more and see how little the Avg actually changes. It most likely will not change by more than the SD was to start with, which tells you all you need to know about the statistical relevance of such small data sets.

 

[SGK]

Yes it works as advertised. I have one. But like any measuring tool it comes with inherent measurement error. That’s why I’m thinking about upgrading to one of these https://www.autotrickler.com/twoboxchrono.html

 

[Delfuego]

SGK: I believe you may be overthinking this. The OP is shooting steel with a 223. Myself and all of our friends have used Magnetospeed to confirm velocity data for ELR rifles. The data collected, was verified and used in ELR matches out to 2k yards. It simply works. I do not believe there is any reason to doubt the product. Is it perfect? Nothing is perfect. Can you trust it, Absolutely.

 

[dsculley]

I agree with South Prairie Jim. You only showed us your chrony numbers without the corresponding targets. Impossible to pick the best load based on that. As far as I am concerned, the target is the final arbiter. Load development at 100 yds. Find the node, load and retest. If it still works, take it to the ranges you want to shoot and test again. If it holds together at range, you are done. As Delfuego said, "Don't overthink it!"

Having the chronograph data, especially SD, is nice. Most people don't shoot through the chronograph enough to get statistically significant data to develop loads based on chronograph data. To do so would use up too much barrel life. We use estimates based on small samples.

While I do use a chronograph during load development, it is primarily for watching muzzle velocity increases as a means of monitoring pressure. If the load I develop will hold 0.5 moa vertical or less at the ranges I shoot then i really don't care what my chronograph says about the SD/ES.