On Tue, 05 Mar 2013 10:21:57 -0500, Joe Gwinn
wrote:

In article , John B.
wrote:

On Mon, 04 Mar 2013 11:48:11 -0800, Gunner
wrote:

On Mon, 4 Mar 2013 10:12:53 -0800 (PST), "
wrote:

On Mar 4, 9:47*am, Ed Huntress wrote:


I think he's overly worried about taper. He shouldn't have any
measurable taper over that short stroke. If he does, he has bigger
problems with that lathe.

--
Ed Huntress

I also think he is overly concerned about taper. I think that taper
is a non issue. If the die has a lot of taper, will it make any
difference? The lead will be the size of the smallest section of the
die.


Dan

Taper does indeed make a huge difference in the application. Most
bullets are aprox .001 bigger than bore diameter. Squeezing it into
the bore means it becomes squeezed by the rifling and it tends to
spread in the grooves and be impressed by the lands.

Marlin Microgroove rifling is much shallower..but there are many many
more lands and grooves so they dont protrude as much. If the bullet is
too small, or the bore bigger than "normal"..it tends to not engrave
and spin the bullet properly..but simply be shoved enmass through the
barrel, peeling off bits of lead until it is small enough to be pushed
out the end of the barrel with less than proper spin to keep it
stablized.

"Normal" lands and grooves can be found on barrels that are also
oversize. So while the lands and grooves are sharp and proud..they may
not be big enough in that fat bore..to suitibly grab and control the
bullet and it too..starts cutting off bits and pieces unit its bore
diameter and is pushed out the barrel..with less spin than normal..and
with significant damage. Lead is much much softer than copper/nickle
alloys...so they tend to be far more fragile. Think of it as putting
a spike in a bank to hold your boat. If its sand...its a long walk
home. If its solid dirt..it will hold your boat until you return.

I shoot a lot of military bolt action rifles from many countries. Some
of them have "normal" barrels with oversized bores. So making the
bullets bigger is pretty much required when shooting lead bullets.
When they are much bigger..they dont work as well for the reasons
above. In those cases with a tapered bullet..you may get the front
engraved..but the back is simply skipping along behind the engraved
section. This may or may not shoot very well. If the bullet is small
at the front and big at the ass end..it may very well be turned
slightly sideways as it goes down the barrel and be very very
unbalanced after leaving the barrel.

When you are dealing with spins of 150,000 rpm -200,000 rpm..having an
unbalanced soft bullet is not condusive to good accuracy, let alone
having the bullet break up in flight....shrug

Now if the taper was small at the bottom of the die and big at the
top..we may or may not have a good bullet flight. If its small at the
mouth of the die and big at the ass end..its going to rip itself up as
its being sized, then slightly compressed, expanded at the bottom of
the die, and then ripped yet again as its being pushed back out of the
die. We are talking only a thousanth or so..yes indeed..but a good
bullet is now badly damaged at those RPM ranges and wierd ****
happens.

Gunner

Assuming that you are using the sizer die as designed - pushing the
bullet all the way through it - the sized bullet will be the diameter
of the smallest portion of the die.

Two diameter bullets were not exactly uncommon - paper patched bullets
for example are bore diameter (over the lands) while the paper "patch"
is groove diameter. Most artillery rounds are also bore diameter (over
the lands) with a copper driving ring of groove diameter.

One thing that occurs to me is the Minie Ball design, even though this
isn't a muzzleloader. A hollow tail could be forced into the rifling
grooves by gas pressure, so things need not be so precise.

http://en.wikipedia.org/wiki/Mini%C3%A9_ball

Joe Gwinn

The hollow base wadcutter works the same way. However....hollow based
bullets are very speed/pressure limited. If they are fired with too
much pressure behind it..as they exit the bore..the remaining gas
pressure behind it will blow out the hollow base into a balloon shape
which generally will destroy the bullet immediatly or in flight due to
uneven swelling and the sudden imbalance.


The methodology of the left has always been:

1. Lie
2. Repeat the lie as many times as possible
3. Have as many people repeat the lie as often as possible
4. Eventually, the uninformed believe the lie
5. The lie will then be made into some form oflaw
6. Then everyone must conform to the lie