Weatherby Rifle freebore question

Mudduck

Mudduck

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My understanding is that Weatherby rifles chambered for Weatherby specific cartridges have extra freebore to reduce pressure and increase velocity. I assume this would be the same for both their Mark V and Vanguard rifles?

Do the Mark V & Vanguards also have more freebore for non Weatherby calibers compared to other rifle manufacturers? Or do they ream to industry standards? If there are industry standards

So, if I was to take a Remington and a Weatherby Mark V both with same twist rate and both chambered for 300 Weatherby my assumption would be the Weatherby rifle would have more muzzle velocity because they increase the amount of freebore

Is this correct?
 
From what I know a weatherby chamber is desighned with the extra freebore just like 556 NATO so a remington should be reamed with freebore but stranger things have happend
 
Saami specs are what all factory rifles are supposed to be chambered to regardless of maker.
Exclusions would be wildcat custom chambers of which there are no real industry standards to follow.

RC
 
Jamming a bullet into the lands will not always put pressures up, going the other way, sticking the bullet further in the case will reduce volume and most certainly put up pressures. Most factory guns have a huge jump to the rifling which will not improve accuracy. There is more to it than this but these are the basics. Accurate guns need to be able to touch the lands without the bullet falling out of the case. You may not care about this in a hunting gun, whatever the game, fear of function issues with less skilled operators may be the more important issue.
 
RockChucker said:
Saami specs are what all factory rifles are supposed to be chambered to regardless of maker.
Exclusions would be wildcat custom chambers of which there are no real industry standards to follow.

RC
Click to expand...

Sako's in weat cals don't have weat freebores
 
Weatherby stopped the long free bore when production was changed from JP Sauer in Germany to production in Japan (about 1970). They altered the factory ammo at that time as well.

The standard throat today gets the same velocities that the long free bored ones used to get, and it is achieved with less powder. I think the free bore thing was done just so Weatherby could show loads with more powder than other cartridges.

Weatherby cartridges achieve high velocities because they are large capacity cases...

Excessively long throats simply reduce pressure and velocity and shorten barrel life.
 
Where you have to be careful is there are reamers out there for WBY calibers with much less freebore . Reason is some guys feel that freebore hurts the accuracy . One of my shooting buddies had his 30-378 barrel set back , rechambered without freebore

One of the 257 Wby my friend build has no freebore . Needless to say loads for my 257 Mk V is over pressured in his . I have some souvenir brass from his rifle where the primer pocket is so loose you can't seat primer...it just falls out !

Those loads show no pressure signs in my factory WBY

I could be wrong but the Wby factory guns ( certainly the Acrametal / Saco made Wby ) have the longer freebore ( about .350 throat )

My factory Accumark 30-378 has such a long lead that I'm not even close to touching the lands ( seem to recall measured at over .200 )
 
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The term free bore has many meanings for many people.

I consider free bore is where the rifling is removed for 1/2 to 3/4 of an inch... a bullet seated in the case won't come close to the rifling.

A throat length of .350 in a 30 caliber is very close to a standard throat... and not considered free bore.
 
As well, Weatherby has changed the freebore over the years. One of the earliest Wby rifles I have (in 375 Wby) has about 3/4" of freebore. My German built Mk V in 300 Wby has about 1/2". A Win 70 I own in 270 Wby has about 3/8". A custom 340 is closer to 1/2". Just need to measure what you have I guess . - dan
 
Mudduck said:
So, if I was to take a Remington and a Weatherby Mark V both with same twist rate and both chambered for 300 Weatherby my assumption would be the Weatherby rifle would have more muzzle velocity because they increase the amount of freebore

Is this correct?
Click to expand...

If you used a load worked up in the Remington to max. levels, and fired it in the Weatherby with more freebore, you would most likely have less velocity. The freebore allowed Weatherby to load with increased powder weights/velocity while maintaining safe pressures .
 
9.3mauser said:
If you used a load worked up in the Remington to max. levels, and fired it in the Weatherby with more freebore, you would most likely have less velocity. The freebore allowed Weatherby to load with increased powder weights/velocity while maintaining safe pressures .
Click to expand...

The free bore required more powder to be used to achieve the same velocity that a shorter throat gets with less powder. I think that is why Weatherby stopped chambering with the excessively long throats. Shorter throat = longer barrel life and accuracy.
 
The free bore also varies from cartridge to cartridge


What is the throat length (free bore) on your Weatherby® rifles chambered for Weatherby® magnum calibers?
Cartridge Throat length (free bore)
.224 Weatherby Magnum .162
.240 Weatherby Magnum .169
.257 Weatherby Magnum .378
.270 Weatherby Magnum .378
7MM Weatherby Magnum .378
.300 Weatherby Magnum .361
.340 Weatherby Magnum .373
.375 Weatherby Magnum .373
.378 Weatherby Magnum .756
.416 Weatherby Magnum .239
.460 Weatherby Magnum .756
.30-378 Weatherby Magnum .361
.338-378 Weatherby Magnum .361
 
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