How do you measure your free bore...how can it have anything to do with how long you can seat a bullet?
From what I have read about weatherby chambers it is more of a pressure release method? :confused::confused:
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How do you measure your free bore...how can it have anything to do with how long you can seat a bullet?
From what I have read about weatherby chambers it is more of a pressure release method? :confused::confused:
Measuring it, I don't know specifically. But how it effects seating depth... Freebore is the amount of space between the end of the chamber and where the lands of the rifling begins... The longer the freebore, the further out you can seat the bullet... because it's not engaging the rifling until it reaches the lands.
Roy weatherby was a big proponent of jump. To seat bullets long in a weatherby chamber defeats their entire purposeQuote:
Originally Posted by noname
Most if not all the Weatherby calibers are large. Large calibers like a jump to the lands. Small calibers can and will work well with the bullets jammed into the lands.
Example: 6 BR set to a jump to the lands will show pressure at a certain point.
That same bullet and same powder charge, jammed into the lands, won't show pressure at that same point and you can go higher in charge before you start seeing pressure.
ALL of my chambers are cut with ZERO freebore. I start off with lighter (shorter) bullets and go heavier (longer) as the throat wears.YMMV.
Freebore can be a fickle *****.....zero freebore works well on some calibers, but disastrous in others. Weatherby used long freebore to reduce pressure spikes in his overbore magnums. The length of freebore is not as important as the diameter of freebore. I know a barrel maker that intentionally put 16" of freebore on a 6 PPC barrel. Much to our surprise, it shot just as well as one with .060" freebore.
To get a good idea of what your freebore length is, lightly seat a flat base bullet upside down and then chamber it to push the bullet in until it stops. The length between the neck and the end of the bullet is the freebore length.
Sharpshooter is absolutely right! But my question is: Are you really trying to determine your Freebore? Or are you trying to determine distance to the lands with a specific bullet? Different bullets will meet the lands at different base to ogive lengths. Even if they are in the same weight class.
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All of my rifles have custom barrels with the freebore diameter so close to bullet diameter it's difficult to chamber a cartridge if there is any foreign material in the freebore area like a thread from a patch. The reamer is ground so the freebore is only .0002 greater than the standard bullet diameter for that caliber.Quote:
Originally Posted by sharpshooter
This allows me to seat bullets long enough to keep the boat-tail out of the powder space yet still have some jump. So far, every rifle I've had chambered that way shoots sub .25 MOA with a variety of bullets (as long as I get the load worked up correctly).
well,thats clears things up pretty much..I knew that know it all at the range
didn't know what in hell he was talking about..He tried to say that was how
to determend bullet jumb or whatever he was trying to say..LMAO
Ok, we have to split this in two parts.
Freebore: That is the distance from where the bullet is seated in the case, to the lands.
There is a huge difference between a gun with shorter than spec bore.
Once you find out where your bullet hits the lands, then you can pull it back .005/.010/.015 etc and that is YOUR FREEBORE.
You can have that freebore on a short bore barrel if you hold the bullet back (and your powder allows it to be seated deeper)
The end of the bullet is NOT the data point, its where the OGVIE of the bullet touches the lands.
Thanks for clearing that up RC. I was getting lost. What is jumb? Is it similar to jamb? or jam? Where is the peanut butter? http://www.gunslot.com/files/gunslot...ages/54067.jpg