Help with stabilizatoin issue. where do I go from here?

[Whiterabbit]

You know, I just found that yesterday while doing some googling. That spinning too fast (or was it too fast a linear speed? I'll try to find the resource again) can introduce instabilities into imperfect bullets from precession.

Slowing the bullet down is definitely on the list of things to try now.

[Whiterabbit]

Hey Hey, here's an interesting tidbit to compare to the Hodgdon website:

Robert Palermo /Penn BulletsJuly 16, 2010, 02:39 PM
The best way to determine is that H110 and ww296 must be at the minimum of 80% case capacity for reliable ignition. That is the threshold mark. figure out what total case capacity is and then see where your load figures in at.

From the high road .org. That's straight from the horses mouth right there, Robert cast the bullets I'm using. I have a date tonight with a scale, caliper set, and a powder trickler!

[Brd_Hntr]

Could you try the load using a similar bullet with a gas check to protect the base of the projectile?

[ejhc11]

Do a search for the Greenhill Formula it'll help you know which bullets work with your twist ratio.

[Sub95]

I am trying to use common sense and see what are the real difference of the two loaded rounds are, not using some stability calculator or anything else. need to break down both rounds and see what else is different other then powder charge and weight of bullet. if you can get the 300 grain bullet to not key hole you should be able to get the 340 grain bullet not to key hole to. doing this step by step as there are other things that can cause your problem.

1, Are they both 100% lead bullets and same style?

2, loaded oal on both? if the 300 grain is closer to the rifling then the 340gr, it could cause a problem.

3, the crown on the muzzle can cause problems, worn barrel, under sized bullet ect all can create a tumbling bullet.

[NotEnufGarage]

Probably a 45 Colt or 45-70 Government. I want to say 45 Colt from the 16" twist rate, but 1700 fps is very fast for a 300-340 grain cast bullet in 45 Colt, even from a 20" rifle barrel.

I think it's S&W .460 Magnum.

OP - please provide the firearm make and model, COAL and any other pertinent information and we might be able to help.

Sidenote - you're shooting lead at 1900 fps? Seems a little high to me, without gas checks. What's the barrel look like after a few round? You might be all fouled up so no rifling action is occuring.

[gunboat]

Sometimes reloading seems to digress from science to art -- try different powders, bullet diameters and perhaps lubes.
my tuppence

[cjskalka]

I am speechless

[Antihero47]

I think it's S&W .460 Magnum.

OP - please provide the firearm make and model, COAL and any other pertinent information and we might be able to help.

Sidenote - you're shooting lead at 1900 fps? Seems a little high to me, without gas checks. What's the barrel look like after a few round? You might be all fouled up so no rifling action is occuring.

This.

[noylj]

Keyholing

Generally, either the bullet is not gripping the rifling or the rifling is shallow/bad (i.e., lead or copper build up). In both cases, an examination of a fired bullet will show if the bullet held the rifling or not.
IF the original good load was a cast lead bullet and it is still shooting fine, that would rule out the gun/barrel.
I would love to run that barrel with my Foul-Out III for a couple of cycles and see what could be pulled from it...

[Fishslayer]

I can give all sorts of details if needed. Can you go into some detail about what the cartridge overall length has to do with bullet stabilization? Also what the difference is between lead, jacketed, and copper that DOES NOT have to do with length.

Cause the internet tells me (and the internet is always right, right??) that even bullet weight is not really critical to stabilization, compared to length. That bullet length is the main dictator of stabilization.

But really, if I start providing all sorts of numbers, presumably it's gonna go into an equation of some sort, right? What's the equation? If it's qualitative stuff, all the numbers don't mean so much, right?

Sounds like ya already know everything. Why are you asking us?

[freonr22]

[sonnyt650]

More fuel for the case capacity fire: there was a recent thread where the velocities were either as expected or some large amount less, wonder if the occasional keyhole is that way. Excess case capacity caused inconsistent powder burn -- would have never guessed that myself.