More Questions

[darrindlh]

Hello,
I know that I have posted a-lot of questions. I have another question , I'm sorry. I just enjoy learning from people who know more than me! So i am going to load my factory Vangaurd 300 weatherby to an over all length of 3.750. Today I measured the lands of my vanguard at 3.994 . That would be .244 free-bore. I know my 300 weatherby normally has free-bore of .361. I plan to load the 215 berger hybrids and I am hoping for a velocity of 2900 fps. Am I going to reach pressure signs sooner? is .244 enough to keep pressures in check? Or am I confused as to why weatherby uses free-bore.

Darrin

 

[cdherman]

.244 free bore is huge by most of our standards. WBY is famous for long free bore -- you get more velocity that way, cause you can load the cartridge hotter and not get as much problems with pressure. When WBY started out, range finders didn't exist. So the fastest shooting gun had the best success at what was long range in those days, say 300 yards. And the loss of accuracy from that long free bore didn't matter over those ranges.

If you are using loads that are designed for a .361 free bore, you *might* get pressure a little earlier at .244. But I doubt it. Published loads are often conservative. You joined in 2009, so you must not be a total nube -- you should be looking for pressure signs as you work up a load.

Figure out what is your max COAL to work in the mag and work up a load. Doubtful that playing with seating depth will matter much with that much with that much free bore. I have read that some WBYs like a crimp -- I tried this with my buddies 340. I tried enough with various bullets and powders that I had several black and blue shoulders and I still could not get that gun under 1 MOA with heavy bullets. But YMMV......

 

[Tiny Tim]

Don't confuse freebore with jump. The distance between where your bullet is in a loaded round and engaging the lands is jump. Freebore is a fixed amount of lands removed by the chamber reamer.

As above. Load it and work up your powder charge and let the rifle tell you what it likes.

 

[darrindlh]

.244 free bore is huge by most of our standards. WBY is famous for long free bore -- you get more velocity that way, cause you can load the cartridge hotter and not get as much problems with pressure. When WBY started out, range finders didn't exist. So the fastest shooting gun had the best success at what was long range in those days, say 300 yards. And the loss of accuracy from that long free bore didn't matter over those ranges.

If you are using loads that are designed for a .361 free bore, you *might* get pressure a little earlier at .244. But I doubt it. Published loads are often conservative. You joined in 2009, so you must not be a total nube -- you should be looking for pressure signs as you work up a load.

Figure out what is your max COAL to work in the mag and work up a load. Doubtful that playing with seating depth will matter much with that much with that much free bore. I have read that some WBYs like a crimp -- I tried this with my buddies 340. I tried enough with various bullets and powders that I had several black and blue shoulders and I still could not get that gun under 1 MOA with heavy bullets. But YMMV......

CDHerman,
You are right, I am not a newbie, and I usually work a pressure test when testing a new powder. This is the first time ive reloaded a weatherby cartridge. I will start with an OCW test watching for pressure.

Thank you both for replying. I am grateful

Darrin

 

[darrindlh]

Don't confuse freebore with jump. The distance between where your bullet is in a loaded round and engaging the lands is jump. Freebore is a fixed amount of lands removed by the chamber reamer.

As above. Load it and work up your powder charge and let the rifle tell you what it likes.

So when I tool my OAL guage I assume I was measuring where the bullet touches the lands. So would Free-bore begin after a space that rifling is taken away? Or am I measuring wrong?

Darrin

 

[Bucklowery]

 

[Rflshootr]

Don't confuse freebore with jump. The distance between where your bullet is in a loaded round and engaging the lands is jump. Freebore is a fixed amount of lands removed by the chamber reamer.

As above. Load it and work up your powder charge and let the rifle tell you what it likes.

So, by your definition, if you calculated exactly where the bullet would touch the lands if the reamer/chamber/throat was at zero free bore, and you seated the bullet exactly to that point, but the chamber actually has .100 of free bore, would that .100 that the bullet moves to engage the rifling be jump or free bore?

 

[Taylorbok]

So, by your definition, if you calculated exactly where the bullet would touch the lands if the reamer was at zero freebore, and you seated the bullet exactly to that point, but the chamber actually has .100 of freebore, would that .100 be jump or freebore?

Your question is confusing you can't have zero FB and .100.
Free bore is the distance of rifling that has been removed by the reamer ahead of the neck.
Jump is the distance your bullet moves before it engages the rifling.

 

[Rflshootr]

Let me rephrase so you'll understand where I am going with this. If you chambered a barrel with a .000 free bore reamer, and then found the length of where a loaded round just touched the rifling and you had that measurement, then you pulled the barrel and throated it for .100 free bore and reinstalled it, the bullet should have to move .100 further out to touch the rifling, correct? If you now fired that round that was seated at the original measurement, is that jump or free bore that the bullet is moving?

 

[Taylorbok]

Let me rephrase so you'll understand where I am going with this. If you chambered a barrel with a .000 free bore reamer, and then found the length of where a loaded round just touched the rifling and you had that measurement, then you pulled the barrel and throated it for .100 free bore and reinstalled it, the bullet should have to move .100 further out to touch the rifling, correct? If you now fired that round that was seated at the original measurement, is that jump or free bore that the bullet is moving?

In that case it'd be both.

 

[Rflshootr]

I beg to differ, but, No, it is not. But that was trying to have a safe answer on your part, I'll grant you.

 

[Taylorbok]

I beg to differ, but, No, it is not. But that was trying to have a safe answer on your part, I'll grant you.

Either you're wrong or I don't understand your question.

If a chamber has ZERO FB and you load a round to touch, then you take that chamber and give it .100" FB you've pushed the lands ahead so that round now has .100 jump

 

[Rflshootr]

OK, let me explain. Free bore is the amount the ogive/body of the bullet can move in a supported diameter of the barrel, usually .0005 larger than bullet diameter, before it engages the lead angle of the rifling and is still engaged in the neck of the case.
Jump on the other hand is when the base of the bullet has left contact with the mouth of the case and is no longer supported by the neck. At that point, the additional amount of forward movement of the bullet until it contacts the lands, is jump.
It's pretty common on Weatherby's and other long throated chambers when shooting mid to lightweight bullets.
Have you never had a rifle that you couldn't reach the lands with the bullet that been selected but if you go to a heavier, longer bullet, you can? It's a sure sign of 1 of 2 things or a combination of both...a long free bore or a worn throat.

 

[Rflshootr]

Either you're wrong or I don't understand your question.

If a chamber has ZERO FB and you load a round to touch, then you take that chamber and give it .100" FB you've pushed the lands ahead so that round now has .100 jump

No. It has .100 free bore. Think about jumping rope or hopping over a creek to keep your feet dry. Do your feet leave contact with the ground? Same as the mouth of the case.

As you probably can tell, I like to try to make people think for themselves, and picture in their minds, about what is actually happening, when bad information is given.