Range Report New MagnetoSpeed v3 SD question

[M113A3]

Hi all,

Just getting started with bolt guns and decided to pick up a v3 and test the factory rounds I zeroed the rifle with. I plan on reloading for this rifle and wanted to have a target starting point for load development.

My question is it typical to see the SD drop as the barrel warms up?

Thanks!

I shot 4 strings of 5 rounds with the following results.

Series1 Shots:5
Min 2391 Max 2418
Avg 2404
S-D 12.1
ES 27
Shot Speed 2417 ft/s 2391 ft/s 2397 ft/s 2418 ft/s 2401 ft/s

Series2 Shots:5
Min2385 Max2401
Avg2395
S-D 7.8
ES 16
ShotSpeed 2400 ft/s 2385 ft/s 2401 ft/s 2388 ft/s 2401 ft/s

Series3 Shots:5
Min 2405 Max 2415
Avg2410
S-D 4
ES 10
ShotSpeed 2405 ft/s 2412 ft/s 2415 ft/s 2413 ft/s 2408 ft/s

Series4 Shots:5
Min 2395 Max 2403
Avg2400
S-D 3.3
ES 8
ShotSpeed 2395 ft/s 2403 ft/s 2401 ft/s 2403 ft/s 2401 ft/s


Rem 700 with a 16.5 inch barrel 1:10 twist
Federal GMM 175 grain SMK

 

[Wildcat455]

If you started with a CLEAN barrel, maybe you've found a round count for consistency with the fouling in your barrel and that ammo?
Probably be easier for you to poke around with it and see if you can figure out what's going on. Pretty sure most of us would be just guessing. I think there is Insufficient data at this point.

 

[Subwrx300]

I ran all the numbers you posted as if they were in a single String to check SD over the larger sample (all 20 rounds in sample). This graph shows all shots and averages for total string:

While it does seem that the SD is reducing, if you look at the averages, it shows that if you were to have used shots, say, 9-13, you would have seen a much higher SD and the average velocity for any given 5 shots its pretty variable but stays within the SD for the sample. The overall SD from start to finish is 9.16; if you ignore the first 10 shots, you get an SD of 6.31. Yes its possible that your SD may stay in the 3-4 range but I'd guess it was simply luck of the draw that it continued to get smaller. 5 shot sample strings are (statistically speaking only) very small with high uncertainty.

 

[M113A3]

Thanks guys - real new to this and was just testing the v3. When I start load development what would be consider a large enough sample size to obtain useful date for a given load development?

 

[padom]

5 shot string numbers are just an indicator. You really need to shoot 20-25 to get a real world SD

 

[Lonestar1027]

Without stressing about confidence intervals, sample size, DOE, etc.. I typically use 10-15 shots and base my SD off of those values.

Might be a good read for your decision process:
https://www.autotrickler.com/blog/thinking-statistically

 

[M113A3]

Thanks for the link I will check that out. I wanted to mention that the four strips I listed were actually sequential. The reason for the separate strings was that I saved the data after each 5 round mag. Additionally the barrel was clean and the first shot of the string #1 was the cold bore shot. <<< this almost sounds like I know what the hell I am talking about

 

[Subwrx300]

Thanks for the link I will check that out. I wanted to mention that the four strips I listed were actually sequential. The reason for the separate strings was that I saved the data after each 5 round mag. Additionally the barrel was clean and the first shot of the string #1 was the cold bore shot. <<< this almost sounds like I know what the hell I am talking about

Good to know. I think the last 15 shots would be more indicative of your potential load/barrel. Welcome to the often confusing and addicting world of Long range shooting!

 

[M113A3]

Thanks man... As I get set up to start loading some rounds i am sure I will be back with lots of questions.