Resizing slugs

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bigHUN

bigHUN

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Jan 16, 2020
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I am a big fan of resizing pellets, and planning to make one setup for slugs as well for next incoming season.
I have couple liners in .22 and .25, I slugged each of them, and I measured with micrometer and documented in microns (not inches).
Now my tricky question comes to serious experts in the field :) :

Why would I re-size the slugs larger 0.0005-0.001 microns then a "Groove" (any of my calibers) ? if that creates an extra possible variable with friction inside rifling ?
Why not half micron to one micron smaller then the Groove?
The rifling Land is already there to manage the twist rate, and that amount of friction already not equals to Zero.

I was looking several times into MOE bushings, but hold my purchase back because they fabricate in inches - I am finding their ID sizes very rough (incrementals in thausands of inches) to my liking.
I will eventually buy couple bushings in .22 and .25 a little smaller ID - and rework = hone and polish the ID to my needs.
Most likely I will end up with couple sizes - undersized, just to test this my theory.
Slugs shall be undersized, the small blow buy is still smaller energy waste then a friction to the groove? No matter how much you can polish your liners/barrels.
And btw there is a choke anyway in every possible FX liner.
 
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I size my high power airgun slugs to .001” under the groove diameter. That’s still .005” or .006” greater than the bore diameter . So plenty of engagement with the lands. And that displaced lead has to go somewhere. Hopefully into the .0005” groove spaces to seal the area. And I prefer slugs with driving bands. A bore rider with a narrow driving band gives a decent seal with less friction.
 
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With a standard sizing setup, it's almost a guarantee that you will degrade accuracy potential because the slug will mot go through the sizer square every time. It's no different than a chamber that isn't perfectly concentric or one that simply uses a taper to load the slug. Start it out a little crooked and it will remain that way. I made slug sizing dies that have the first section as a parallel chamber that fits the slug very closely before the sizing portion. Even so, they still don't give me the same score averages as untouched slugs.

Most will probably not realize or care about the difference, but it's there.

Mike
 
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thomasair said:
With a standard sizing setup, it's almost a guarantee that you will degrade accuracy potential because the slug will mot go through the sizer square every time....
Mike
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Yes, I have that in my mind. Theoretically that shall be easy to correct, but I would need couple samples to investigate. I know it is a trial and error. A little conical lead in shall help.
I know swaging slugs from wire is a best way to go, I did my calculations and cannot justify the expense. At my place (Toronto and area) I don't have anybody to compete with airguns 50-100 BR. Unfortunately me shooting airguns alone in N.America's one of the largest gun club.
 
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You guys talking inches and thousands just to confuse me? ;)
The difference between .217 and .218 is huge... it's like a schoolbus. :)
25 microns.
(A side note only, When I started my engineering careers in a high precision company we were making a shaft slide freely in a hole with 5 micron gap. That was called DIN standard.)
OK, joke aside.
I will make some drawings for my local cnc shop and order couple bushings. I think I still have a 6-7 mm honing tool somewhere in my toolbox, but I will also check on ali.
 
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Ezana4CE said:
Are y’all using the same type of lube that PB reloaders use when sizing slugs?
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I do things a bit different, using the same silicone oil that I shoot the slugs with as sizing lube. I throw the new slugs into a tin with silicone oil on the foam and size them wetted and they size through the die easily. I don't want to introduce the thicker powder burner type of lube into my bore; the light silicone oil is pretty consistent no matter the temperature/weather.
 
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Ezana4CE said:
@Airgun-hobbyist Thanks. I was reading about a lubricant that’s like bees wax that hand loaders use. It starts with an “a,” but I forget the name. I recall reading that lubing before sizing prevents the sizing die from getting leaded up. I really don’t know much about any of this.
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I've never had a leading issue using the silicon oil, and I do mostly big bore sizing that sometimes needs a lot of squeezing down to size. When reading about sizing bullets on the powder burner forums, they are doing multiple things, ultimately pushing them into brass, so it's a different animal when lube is involved.
 
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