discussion on tumble lube design

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07 December 2004, 14:36

DE Hillyer

discussion on tumble lube design

Hi All! Tumble lube bullets can shoot very well but it seems at a lower velocity than other plain base bullets. And I wonder why?

Does the bullet not carry enough lube???

OR....is there not enough metal at the groove diameter...? The bands look like a flattened circle or an oval. Imagine that the band was cut in half...and a flat section was added. I'm not talking a great amount. Maybe 50% of the total width of the entire individual driving band.

Look at a factory bullet design...such as any of the designs on the Lee site. http://www.leeprecision.com/cgi/catalog/browse.cgi?1102382569.1592=/html/catalog/bullmol2.html
You can see how much wider the base band is. Imagine the other tumble lube bands maybe half this width. More metal out at the groove diameter for more support. Would it help?

Thanks, Dale

07 December 2004, 19:39

Leftoverdj

Are we talking rifle or pistol here? And what type of rifling are we taking about?

08 December 2004, 00:50

trk

Quote:

Hi All! Tumble lube bullets can shoot very well but it seems at a lower velocity than other plain base bullets. And I wonder why?

Theory. I'd like to see empirical evidence.

As we know there are a lot of variables - alloy, hardness, lube, weight/length, rate of twist, fit to throat, size in relationship to grooves/bore, depth/shape of rifling, powder burning rate and leading vs. accuracy.

It may be for a given weight of bullet that the tumble lube is better! It may be that there is no 'significant' difference.

Perhaps a test is in order? Two very similar boolets except for groove style?

Maybe there is a body of research that's already been done!