bullet length, weight, and stability.

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bruce m
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Re: bullet length, weight, and stability.

Post by bruce m »

at the sandy hook tests, the govt bullet hit the ground point first at extreme max range.
the bullets followed the axis of the trajectory curve perfectly.
not sure of the twist on those old springfields, but think it slower than 18".
the bullet has a reasonably blunt nose profile, possibly aiding stability right to the end of flight.
not only that, those bullets had pretty surprising penetration at max range of both wood and sand.
those who put their money where their thoughts happen to wander are now the crucible of long range bullet design.
it will be interesting to see what rolls out.
a good chance it might resemble the old sharps bullet of later design, or the metford bullet.
time will tell.
keep safe,
bruce.
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Distant Thunder
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Re: bullet length, weight, and stability.

Post by Distant Thunder »

Kurt,

I'm just wondering how far forward you patch that hunting bullet?

DT
Jim Kluskens
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Kurt
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Re: bullet length, weight, and stability.

Post by Kurt »

Jim I wrap them just above the top groove maybe a 1/16" - 3/32".
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craneman
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Re: bullet length, weight, and stability.

Post by craneman »

While I dont have one, a cannelure tool might be a quick and dirty way to experiment with a groove or two on the rear of the shank of a PP bullet to test the stability theory.

Todd
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Distant Thunder
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Re: bullet length, weight, and stability.

Post by Distant Thunder »

Hmmmm, I believe I have such a tool. I suppose that calls for an experiment. I will give that some thought.


DT
Jim Kluskens
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desert deuce
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Re: bullet length, weight, and stability.

Post by desert deuce »

Each shooter must make their own choice, whether to soar on the winds like shreds of paper or to wallow in grease like a big lump!
Now Jim, it is not like you to completely overlook the obvious even in humor. :? An undersize object of course will enter into and pass through an orifice easily with minimum friction, and, as a few if not many know an oversize object requires lubrication to enter into and pass through the same orifice to minimize the effects of the increased friction due to the tighter fit. As always, it depends on what the orifice in question prefers. :wink:
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bpcr shooter
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Re: bullet length, weight, and stability.

Post by bpcr shooter »

craneman wrote:While I dont have one, a cannelure tool might be a quick and dirty way to experiment with a groove or two on the rear of the shank of a PP bullet to test the stability theory.

Todd
I was thinking a tube cutter myself, but yeah that would work great!!!
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Distant Thunder
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Re: bullet length, weight, and stability.

Post by Distant Thunder »

DD,

Are we still taking about bullets here? Or am I just not reading you right!

DT
Jim Kluskens
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Re: bullet length, weight, and stability.

Post by MikeT »

To get at least one groove near the base of the PP bullet; Just over-crimp with the taper crimp die. That should leave a mark on the bullet. :twisted:

Not to get too far from the topic of grooves, bruce m says the highest bc is attained with a longer nosed bullet. Is it possible that
the two diameter bullet presents the "ultimate long nose" effect? First you will have a normal ogive, then a parallel section and last will be the full grove diameter. The bullet could be resembling a "cone" shape 'in-flight', with the point being the smallest cross-section and gradually increasing in diameter until the base of the bullet has the full grove diameter.

DT, will you and beltfed have a proto-type bullet at the Fall Lodi match?

Keep on hav'n fun!
MikeT
Coltsmoke
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Re: bullet length, weight, and stability.

Post by Coltsmoke »

I was about to order a PP mold, now it seems the GG bullet is more stable. PP bullets with grooves and 2 dimensional, Hmmmmm. May be time to wait and let the dust settle a bit after some more testing has been done. :wink:
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bruce m
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Re: bullet length, weight, and stability.

Post by bruce m »

mike t,
recovered dual diameter bullets have paralell shanks.
you would not know that they were ever dual diameter.
the bore diameter front section bumps into the rifling right up to the ogive just like any other bullet.
bullets which patch to bore full length, and fired in a greaser chamber, become dual diameter before they start to move because the part in the case bumps up to whatever is the internal diameter of the obturated case.
this is why making the bullet d.d. in the first place is superior.
there is a more instant gas seal there because the bullet is a near perfect fit in the fired case dimension already, just like patched to bore is in a tight pp chamber.
plus there is less working of the alloy at the base of the bullet.
as far as putting a groove in the base of a smooth shanked bullet, i see issues.
first, it could grab the patch and hang onto it.
second, grooves work better with lube in them.
third, using a cannelure tool or such, there is the possibility of changing other dimensions of the bullet, like length or diameter.
this bumpup of pp bullets also happens to long nosed greasers.
only problem there is that they expose a lot of unlubed lead to the bore unless blowtubing is leaving lube in the bore.
here the first shot in a clean barrel is the most likely to leave lead.
keep safe,
bruce.
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bruce m
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Re: bullet length, weight, and stability.

Post by bruce m »

coltsmoke,
pp bullets are as stable as you need if you match the bullet to the twist.
with greasers there coud be some dynamic stability issues with airflow.
some might be better than others.
there exist micro minigroove designs that have proven to have much less drag than bigger grooves.
they only carry enough lube for wiping.
take a good tip and steer clear of bore riding noses with these.
reason being that there is no such thing as a bore riding nose.
that section will bump into the rifling just as surely as that section of a pp bullet does.
and with minimal lube you don't have the fallback position of blowtubing.
keep safe,
bruce.
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Distant Thunder
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Re: bullet length, weight, and stability.

Post by Distant Thunder »

"recovered dual diameter bullets have paralell shanks.
you would not know that they were ever dual diameter.
the bore diameter front section bumps into the rifling right up to the ogive just like any other bullet.
bullets which patch to bore full length, and fired in a greaser chamber, become dual diameter before they start to move because the part in the case bumps up to whatever is the internal diameter of the obturated case.
this is why making the bullet d.d. in the first place is superior.
there is a more instant gas seal there because the bullet is a near perfect fit in the fired case dimension already, just like patched to bore is in a tight pp chamber.
plus there is less working of the alloy at the base of the bullet."

Well said, bruce!

I am of the opinion that the dual diameter ppb design is the best design for grease groove chambers, especially those with any amount of freebore. When a dual diameter bullet is fitted to a specific chamber it sure shoots well.

DT
Jim Kluskens
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bruce m
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Re: bullet length, weight, and stability.

Post by bruce m »

DT,
rule no 1 for accuracy.
fill any space with bullet.
keep safe,
bruce.
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Kurt
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Re: bullet length, weight, and stability.

Post by Kurt »

MikeT wrote:To get at least one groove near the base of the PP bullet; Just over-crimp with the taper crimp die. That should leave a mark on the bullet. :twisted:

Not to get too far from the topic of grooves, bruce m says the highest bc is attained with a longer nosed bullet. Is it possible that
the two diameter bullet presents the "ultimate long nose" effect? First you will have a normal ogive, then a parallel section and last will be the full grove diameter. The bullet could be resembling a "cone" shape 'in-flight', with the point being the smallest cross-section and gradually increasing in diameter until the base of the bullet has the full grove diameter.

DT, will you and beltfed have a proto-type bullet at the Fall Lodi match?

Keep on hav'n fun!
MikeT

Naw Mike all it would do is cut a nice clean hole through the paper and nothing else :D
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