Cold Weld / Wet Tumbling Test

Graye2

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Oct 25, 2018
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Recently there seems to be one or two new cold weld / wet tumbling threads per week. So I started thinking through how I could give back to the Hide for everything I’ve learned by starting a year long test to prove/disprove theories or at least prove to myself what works best for me. I typically don’t leave reloads sitting around very long so I have no idea what to expect. I’m not looking for a doctorate but I’m interested in the results and rather than just wait and post them at the end I thought it would be beneficial to get input up front.


All brass will be once fired Lapua 6.5 Creedmoor SRP that goes through my typical process:
  • Deprimed
  • Wet tumbled with pins, dawn, lemishine in Franklin Arsenal Tumbler
  • Dried in dehumidifier
  • Anneal with AMP
  • Homemade lanolin lube
  • Neck sized with Redding Competition die on a Zero Press
  • Shoulders bumped .002
  • Mandrel set to .002
  • Trimmed and chamfered
  • Vibratory cleaner in walnut and polish
  • Primed on CPS (I don’t typically touch my Lapua brass - pockets or flashholes but if the general consensus is I should I can)
This is where the test will come in with various processes prior to seating:

1) Do nothing control group (what I do now)

2) Necks dipped in dry graphite group (only do this on new brass to open up necks)

3) Brush inside of necks with bore brush - up and down twice on a drill group (used to do this)

4) Bullets will be dipped in Lyman ultra fine dry neck case lube group

I would load up 15 rounds of each group, 20 of my control group. All powder will be dropped with an AutoTrickler with a known load. I will wait to do this test until I can order an AMP press and digitally record all seating pressures. Any round that “fails” the pressure test will be culled so we know we are starting with consistent neck tension across a group. For me this is going to be a huge benefit...not that I can’t do it with a gauge but consistent pressure in vs by hand is one less variable. Hearing late April for release of the AMP and if I can get one and play with it I’ll start the test in May/June.

I would shoot groups as follows recording SD/ES for each group on a LabRadar.

Now: 5 rounds of each of the 4 groups

6 Months: 5 rounds of each of the 4 groups

12 Months: 5 rounds of each of the 4 groups and I will also take an additional 5 pieces of prepped brass from now, save them in the same box, and load them with no neck treatment (I.e. is it the brass/bullet combo or if the brass oxidizes/corrodes over time without a bullet loaded, or nothing at all)

24 Months: 5 rounds of my control group

All rounds will be stored indoors - temp/humidity controlled.

Any other thoughts on what else I should do/or you would like to see? Given the analysis will take more than a year to perform I want to make sure I think through this and then I’ll share my data along the way.
 
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Gregor.Samsa

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    Sounds like a great way to have direct comparisons vs. anecdotal tidbits from others on the internet. I hope the sample size is enough to be conclusive but this is very cool none the less. thanks for sharing.
     

    Graye2

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    I thought about whether 5 rounds would be conclusive (not statistical) and considered 10 but feel like with a consistent process, brass, CPS, AutoTrickler, and the AMP press data the main variable would be the chemistry of the brass/bullet contact. I’m open to doing 10 each too but just wasn’t sure I’d gain much? I’ll see what other comments come in...waiting for the press release anyway.
     
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    Gregor.Samsa

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    I thought about whether 5 rounds would be conclusive (not statistical) and considered 10 but feel like with a consistent process, brass, CPS, AutoTrickler, and the AMP press data the main variable would be the chemistry of the brass/bullet contact. I’m open to doing 10 each too but just wasn’t sure I’d gain much? I’ll see what other comments come in...waiting for the press release anyway.
    That’s also a fair amount of components to have sitting around for a while to test this. I look forward to the results. Thanks
     

    918v

    It’s not the primer!
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    I don’t think your test will be valid. Your way of lubing brass for sizing is bound to place lube inside the neck. Dry tumbling will not get it out. So to do it right you’ll have to change the process by wet tumbling a second time. Only then will you have bare brass on bullet contact which is what we think causes cold welding.
     

    Graye2

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    I definitely get lube in the case necks so I can run my mandrel through. However I do believe my vibratory walnut and polish method removes it as it does the outside.

    But either way you have a valid point and while I was looking at the test more so from my process perspective I can tweak the groups tested to accommodate those that wet tumble to remove lube also:

    1) vibratory walnut/polish control group
    2) vibratory walnut/polish and necks dipped in dry graphite group
    3) vibratory walnut/polish and brush inside of necks with bore brush - up and down twice on a drill group
    4) wet tumble dawn/lemishine control group
    5) wet tumble dawn/lemishine and necks dipped in dry graphite group
    6) wet tumble dawn/lemishine and brush inside of necks with bore brush - up and down twice on a drill group

    I’ll eliminate the Lyman test group and stick to 5 rounds each or 110 cases in total. (I’ll save 5 of each method for loading at 12 months as originally posted and 5 each for 24 months.)
     
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    Painless300

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    Would be very interested in your test data. Thanks for sacrificing your time, brass, powder, bullets and primers. All are precious at this point and time!
     

    phlegethon

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    5 rounds for each will not be statistically adequate unless you have something like an SD of 2 in one group and 30 in another.

    edit: I ran some numbers. To have an 80% chance of having a significant result, assuming the SD in one group was double that in the other, you’d need 70 samples in each group.

    To have that same 80% power with a sample size of 5 per group, the SD in one group would have to be twenty five times more than that in the other.
     
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    reubenski

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    5 rounds for each will not be statistically adequate unless you have something like an SD of 2 in one group and 30 in another.

    edit: I ran some numbers. To have an 80% chance of having a significant result, assuming the SD in one group was double that in the other, you’d need 70 samples in each group.

    To have that same 80% power with a sample size of 5 per group, the SD in one group would have to be twenty five times more than that in the other.
    None of us know jack shit about statistics so quit trying to confuse us.

    "...I ran the numbers..." Uh huh, know who else says shit like that?

    giphy (3).gif
     

    Graye2

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    Any update here? I would like to know if this is a real thing. Thanks
    Apologies but it took so long for the AMP press to come out and for me to get mine that I kinda forgot about this “test” and moved on. Thanks for reminding me…I’ll add it back on to my to do list.
     

    Feniks Technologies

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    Any update here? I would like to know if this is a real thing. Thanks

    I saw you asked Litz during the podcast. Did he answer? I didn’t listen to the whole thing.

    I’m currently working on testing this. As we are selling ammo, it’s pretty important since 90% of our ammo will be clean virgin brass.