Two Questions

[10Turkeys]

Saw Lances post about the case splitting, and I've ask this one question before, but here goes again. Say typical 30-06, 150gr bullet, 24 inch barrel, 3000fps, either case splits or primer pocket loose, how much velocity loss do you think there will be? Question two same scenario with the 30-06. Say the bullet isn't seated right, say 3 thousands run out, and is seated 15 thousands off the lands, will that bullet straighten out before it exits the barrel, or does it leave crooked. If it leaves crooked, assuming whatever twist the barrel is, having a right hand twist, is the bullet going to land to the right of the target, or however it was loaded into the chamber with the run out?

[300RUM]

The velocity loss due to a case split or loose primer will vary depending on how much gas leaks. Basically, the worse the leak is the more velocity you will loose. I have had a chrono on a .308 with 168's at 2650 when a few case leaks occurred and seen velocity drops of 50 to 200 fps depending on the severity of the leak.

 

I don't see how a bullet could be crooked once it is in the bore. The bullet has a bit of length to it and fits very tightly in the bore. My guess is the issue is where the barrel pointed when the bullet exits. Barrels vibrate like a tuning fork when the gun is fired. Consistency in this vibration leads to accuracy, the barrel is always in the same position when a bullet exits. A bullet that entered the throat out of alignment would have to be forced straight to enter the bore. This could cause a spike in pressure that could vary with the amount of misalignment. That could alter the pressure curve as the round traveled down the barrel. The altered pressure curve could change how the barrel vibrates and change the point of impact. I'm sure some precision rifle manufactures, benchrest shooters, and possibly organizations like the USMC Scout/Sniper program have done research on this. If you dig around on the internet you can probably find some studies on this subject that take an engineering degree to understand. Can't help you there, I don't have one.

[PRDATR]

Saw Lances post about the case splitting, and I've ask this one question before, but here goes again. Say typical 30-06, 150gr bullet, 24 inch barrel, 3000fps, either case splits or primer pocket loose, how much velocity loss do you think there will be? Question two same scenario with the 30-06. Say the bullet isn't seated right, say 3 thousands run out, and is seated 15 thousands off the lands, will that bullet straighten out before it exits the barrel, or does it leave crooked. If it leaves crooked, assuming whatever twist the barrel is, having a right hand twist, is the bullet going to land to the right of the target, or however it was loaded into the chamber with the run out?

 

 

Google Weatherby cartridges and "freebore".

[10Turkeys]

I called Sierra Bullets this am. Question number one was answered with I couldn't tell you, but your definitely going to lose velocity, second answer was your definitely going to have some yaw, where it would impact, couldn't tell you to many variables.

[PRDATR]

Load/Shoot/Determine. Who did you talk to at Sierra?

[10Turkeys]

Normally I ask to talk to Tommy Todd, but I think this guy said his name was Paul.

[300RUM]

I drive for a living and have lots of time to think. I spent a little time keeping myself amused with this thread today. If the bullet is the proper size it can not wobble in the bore because it is tightly contained. However, if the bullet starts out crooked while traveling through the leade and into the bore, and is forced into alignment with the bore, it could be damaged. The bullet may leave the barrel still perfectly round but no longer have its mass evenly distributed around it's center line. That would cause it to start to wobble.

[10Turkeys]

300RUM, I believe your statement to be true, that is assuming the barrel is fairly new, and if the lands were worn at all, they would be even. I have heard both sides of the argument, that the bullet would straighten itself out before if left the barrel, and the other side that no way that a bullet would. Like the guy from Sierra said Alot of varibales. Another thing to think about that there is alot of slop in a typical factory barrel, any slop in the chamber area and the bullet might be off center from the get go.