Hi Tim & All!
Well, I think something causes TL designs to be limited in velocity. I'm not really complaining because i like plinkers. But still, I want to know why. I need to make some out of lino or heattreated WW. That would help some.

But back to your info, Tim. Thank you for your time. But I am still wondering...Say the groove diameter of the barrel is .357 and the bullet diameter of the tumble lube bands is .358. So each side of the slug's band is 'compressed' .0005. Those bands can't be very wide at that depth...a little more than the 0.010 you quote. For the massive forces involved inside the barrel, this seems on the frail side to me. But I'm not an engineer and don't play one on TV! ( I hope I did the measurements right)

a few more crazy thoughts...

could the bands be damaged in:

reloading

jumping from cartridge to chamber to bore ( think pressure/temperature/impact)

simply wearing away in the bore

I really don't think the bullets are unbalanced... ( not like this writer anyway! ) as designed. How they are when they leave the muzzle at 1500+ fps is another matter.

I have the Lee 158 TL .38 bullet. At less than 1000 fps, it is as accurate as I can hold in my Winy 94. Get that up to 1300 ( >357 mag) and accuracy drastically degrades....some of the bullets wobble or nearly tumble. The standard lee .357 bullet with the one big grease groove ( and the same alloy)does that with ease and accuracy... hmmm...

If it is damaged bands (& I don't know!) ...is it the weight unbalance or the air drag unbalance... OR both that causes this. One might feed the other in a symbotic relationship....The more you get of one...the more you get of the other...and then the more you get of the first and so on...

I remember the old 173 Govt match bullets were unstable up close but went to 'sleep' out at 600 yds and flew straighter from then on. This was something gyroscopic I think. That may be where they went subsonic too....hmm...can't remember.


Anyway, Thanks to all who have answered. Dale