The other day I watched Hornady podcast #218, about head spacing, etc. I highly recommend it. You can find it on YouTube.

One comment really caught my attention, because I've looked into it before. Jeff Siewert* said that lubrication on the case can double the force on the bolt face. This is mostly a "wear and tear" issue for the gun, but could be a safety issue too. I was taught long ago that the case had to be CLEAN: no dirt, no oil.

I see that the folks doing wet tumbling often use car wax, or similar products, to get cases shiny. I've been wondering how that affects the the way the brass case interacts with the chamber. In my mind it would have to reduce the friction between them. What do you think?

* Jeff Siewert is a ballistics engineer with 45+ years of experience. He's worked on everything from .177 air rifle pellets to 8" howitzers. He teaches classes on projectile design and ballistics to the US military and a slew of ammunition makers. Amazon just handed me his book "Ammunition, Demystified" about 30 minutes ago.

Here's another study on the same subject:
pubs.aip.org/aip/adv/a...t-of-seven

Good info, thanks

Yep,same here. When in the Army we were trained to keep our ammo clean and not to oil the outside of the round/case. Also, to ensure we always run a patch through the chamber and bore to remove any residual oil etc before shooting.

I use a dry tumbler to clean my cases, and I don’t use any sort of polish or additive to the mix. I don’t use any however put into the tumbler five or six pieces of paper hand towel, about 2” wide, that I’ve sprayed with water to help keep the tumbler media a bit cleaner. Apart from that, my cases are clean and without any additives.

I've just skimmed through Siewert's book so far but the part about lubed cases and bolt thrust is on page 100.

Very interesting. I also dont add anything else to my cases other than just tumbling them with a recommended cleaner (I add very little cleaner from time to time, but less than a cap full.

I have some cases to tumble one of these days. I might mark a few bases with a small punch and take some before / after measurements.

Honestly though now that I think about it, case thickness changing volume is probably a greater concern than OAL affecting bolt pressure.

Interesting topic though!

-DallanC

always whipe loaded rounds afterwards..sort of final step... not much needed,either roll down leg with cloth on it,or quick rub over as put into packet... since using frog lube of imperial wax or vasoline..there isnt a huge amount on cases after loading anyway...definately isnt if I clean them with scotchbrite cloth during trimming to length stage. too easy when already in drill to give them a whirl while holding cloth against them.... super shiney in no time other than very base.

I also use Imperial Wax for resizing and there is next to nothing left on the case after sizing, and what is left comes off in the cleaning/polishing process in the tumbler.

Imperial wax is amazing. I simply dab my finger onto the wax in the tin, and that is enough to size four or five cases. I also ‘scrape’ my finger over the case mouth and that is enough for the sizing plug to do those cases. I like Gelan’s idea of using graphite to lube the necks, but not using the wax…it would most likely create graphite ‘mud’ in the case mouth.

the cases look like been annealed if using graphite powder to dip necks..I find when I use it that every 3rd or 4th case is enough...the residue must sit inside dies and transpher to next few cases.

I have no idea as to how many years I have used Nu-Finish in my tumbler media and have had no problems what so ever. I load in groups and store a percentage for years. The Nu-Finish prevents case oxidation of rounds in long term storage.

Bushmaster wrote:

I have no idea as to how many years I have used Nu-Finish in my tumbler media and have had no problems what so ever. I load in groups and store a percentage for years. The Nu-Finish prevents case oxidation of rounds in long term storage.

How much Nu-Finish do you put in with your tumbler media mate? Does it reduce the life of the tumbler media?

Two cap fulls every once in a while. No...It does not seem to effect the life of the media and all

Hi Vince. How's the house hold? Boss just traded in her Saturn for a 2016 Dodge Ram four wheel drive with all the bells and whistles.

Bushmaster wrote:

Two cap fulls every once in a while. No...It does not seem to effect the life of the media and all Hi Vince. How's the house hold? Boss just traded in her Saturn for a 2016 Dodge Ram four wheel drive with all the bells and whistles.

Household is very hectic here at the moment mate. We have my 98 yr old MIL living with us and she is having terrible problems with arthritic hips and legs. I have been ‘sleeping’ in a recliner chair for the past week and a half with a pager waiting to be called, getting up every hour to help her out of bed, then back into bed after going to the loo. I’m knackered, my entire daily routine has been turned upside down and screwed up and tied in knots. Then of course I have things to do during the day…a “honey do” list. Apart from that, we are surviving.

So which truck do you get to take out now mate? Is the new Ram a diesel or a big petrol V8? My youngest daughter wanted a Ram, but they are hellish expensive out here, so she opted for a diesel Isuzu SUV.

Ram 1500 with the 350 ci (5.7) gas Hemi. Not my truck. I still have the Chevy Silverado.

Bushmaster wrote:

Ram 1500 with the 350 ci (5.7) gas Hemi. Not my truck. I still have the Chevy Silverado.

They are a damn fine unit mate…Deb will be happy, except for the fuel consumption

The "Beast" gets 21.9 MPG. Solid Black. No chrome.