Effects of Weight Sorting Brass on Precision

[@tucobenedicto1780]

You do some of the best tests on KZbin.

[@WitchDoctorPrecision]

Thanks!

[@unknown_blank_blank_blank]

Man... I was testing this out with a primer pocket plug and a micropipette. I used water I kept as cold as possible, consistently adding ice to keep the weight/temp stable. I filled a case at a time, and would use a credit card to lop off extra water drops, then weigh on the FX120i. Labeled the 20 cases, and reloaded, shot them with groups and velocity, then did it again. Internal volume changed with every firing, but at the time I didn't trim my cases every shot. I don't have a primal rights CPS, or an AMP press, as well as not sorting my bullets, or neck turning at the time. It does start to enter the realm of time spent vs performance gains, and at that point i would strongly begin to argue the benefits for a benchrest railgun shooter with the ability to chamber their own barrels.

[@unknown_blank_blank_blank]

To also add in; I did have a standard deviation of 0.8 over 20 shots for the first string. Subsequent strings slowly grew to a stable average of 3.6 standard deviation after 3 firings. This was done with 6.5 creedmoor cases from peterson, but I did test out with 10 firings of alpha 6 dasher in a much simpler/quicker test. At this point, my assumption is that because the smaller cases aren't drawn out as long, the consistency is easier kept between the wall thickness of the cases, ultimately leading to a lot of 6mm cases being pretty "easy" to load for.

[@tekanger975]

Hats off to you in the way you set your experiments up and minimize confounding within your results. I did a similar test, but without all the rigor you applied, and was unable to show any clearly identifable difference with Lapua 6BR brass necked to 22BR. I do have around 30 experience in applied statistics in industry and quality assurance, so I am impressed with what you are doing and the resources it takes to get meaningful results as you do with regularity. Thanks for this and the many other studies you have presented.

[@joearledge1]

Ever consider doing a few videos on how to use advanced statistics for laymen reloaders and shooters? I think it would be very beneficial to the community to have more people with the ability to more critically analyze their data objectively. Keep up the good work Sir!

[@WitchDoctorPrecision]

Good suggestion. I was thinking of doing a video on procedural methods and stats. I don’t usually thoroughly explain everything I did for a test because the videos would be extremely lengthy if I did but I can do a video on how I usually do things and the stats involved. Thanks!

[@joearledge1]

@@WitchDoctorPrecision Sounds good Sir! I can't wait to see more of your videos! Thanks

[@javiersp01]

You keep doing great Bryan. Thank you !!!!

[@crvnmrhd]

Great test! Certainly makes me want to revisit this practice and try it again. Thanks for the group shape results too. It's interesting how the light and average cases were very similar in some aspects yet shot very different, and then the same thing happened with the average and heavy. One thing I would look for in Norma brass is case wall thickness. I have a batch that we're different by .006 down near the web, so I gave them a rest. The rifle still shoots good with them, but I feel further testing of that variable needs to be done.

[@Jeff_Seely]

As usual, the video content is interesting and always a source from which to learn. Thanks for time and effort in producing the data and this video.

[@jameslynn8400]

I've been wondering if sorting brass was a thing. It seems to be. Thanks Bryan.

[@hugosalceda1973]

You are a fascinating guy for sure!. Very dedicated 👌

[@misterlewgee8874]

Your content is always interesting and thoughtful. I wonder about the data sample size and statical significance. I wonder if the many of the tests would be repeatable. I'm always aware of costs and barrel wear. I have seen a machine or two that measures internal case volume...this being the aspect that weight sorting is usually seen to reflect. Thicker shoulders might leed to different results due to more energy to expand...or longer to expand ...maybe...as an alternative idea to case volume. I bought primer plugs to measure with alcohol...but this was not practical at all. Keep up the good work and interesting experiments. Thanks 👍

[@WitchDoctorPrecision]

Thanks for tuning in. As for the stats piece, sample size is driven by the size of the effect so in this case seven 5-shot groups for all three of the conditions (105 total bullets) was sufficient to detect the effect of precision when comparing light with average.

[@misterlewgee8874]

@@WitchDoctorPrecision sample size, vs, size of effect.. thank you...for putting that in perspective.. I'd been thinking of sample size when it came to velocity...with idea that increased sample size gives straight line up velocity increase with powder in crease...thus no velocity node. And was sorta losing faith due to sample sizes being small, thus misleading.... Thanks!

[@yukon4545]

Where did you find the weight difference in the case? Suspect the variance in wall thickness, or the difference in extractor groove depth, length of the flash hole...?

[@WitchDoctorPrecision]

I didn’t check. The Aztec code was lower on the lighter piece which made me think it could have been in the neck and/or shoulder.

[@jasonsimes3333]

I think there would be more variance in group size sorting by case volume vs weight

[@anubis8680]

14:12 *awkwardly covers nerdy-freedom boner* no, n,o please geek out more.... Fanboi eyes glazing over... HAHAHA but seriously though, your ability to go into depth as to how and why things are shooting they way they are is PHENOMENAL. I enjoy a bit of shooting myself and this is the extreme end of that rabbit hole I try to avoid. Should I trim my bras.... meh... headstamp sort whatevs... I don't even neck turn and RARELY anneal!!! But then again I am pretty happy with just 1 moa or better... I am sure you would flip your sh*t at getting a .8 group. So the question is, are you hydraulically and or mechanically locked in to the rest? how much human interaction do you remove from firing? Heart rate steadying and breathing practices... I have found like... an extra cup of coffee while trying to zero can mess me up bad. Depending on magnification and heart rate and tension and firearm weight.... There's so many factors are you shooting in a 100 yard enclosed tunnel? random ass winds you can't call or get a read on... Data is great and your aggregation if wonderful but the X variables... that's why I can only go so far...

[@WitchDoctorPrecision]

The style of shooting is called “free recoil” which means that the rifle is set tightly (not locked into) in a front rest and rear bag. I made a video about the type of shooting style I use if you want more info. This eliminates a lot of human error like what you mention because the only thing I touch when firing is the trigger and this trigger is set at around .1-.2 ounces. As for wind, I will use wind flags if wind is a factor. This enables me to be sure to shoot in the same wind condition. If it is a super windy and/or stormy day, I simply will not shoot. I take great care to rule out as many known variables as possible and it is looking like this method is working if I can statistically detect an effect after shooting seven 5-shot groups for each of the three types of brass.

[@huntmulies39]

great video. Question. did you happen to check the headspace "aka shoulder set back" on each case to make sure the brass thickness isn't effecting the sizing process?

[@WitchDoctorPrecision]

No, not in every one every time. I do “quality checks” where I do check at least a few here and there so that I can detect when the die is not sizing all the way. What I found is that annealing reduces the variability in bump from up to .002” to no more than .0005”. I annealed after every firing in this brass and my quality checks showed no variability greater than .0005”.

[@huntmulies39]

@@WitchDoctorPrecision Thank you

[@johnkennedy6331]

Thanks!

[@WitchDoctorPrecision]

Appreciate the super thanks!

[@johnkennedy6331]

Could you do water case capacity on the same brass and show the comparison of WCC and weight. I have done no testing but I have a personal belief that WCC is what makes the difference and weight is irrelevant. Thank you!

[@WitchDoctorPrecision]

I’ve had more than a few comments about case capacity so I will add it to the list.

[@garnetgaming4368]

Love you Bryan/daddy!

[@WitchDoctorPrecision]

Love you my sugar!

[@johnplummer1619]

What balance did you use for your test

[@WitchDoctorPrecision]

I used the scale on my RCBS Matchmaster.

[@tallyman15]

I you tried Lapua brass?

[@WitchDoctorPrecision]

Yes, not a big fan for the 6PPC. I would use Norma over Lapua in 6PPC all day.

[@JacobTerherst]

@@WitchDoctorPrecision interesting, I’m sure you have an excel spreadsheet to show why, and feel free to share. Keep up the good work.