Stonecreek

That last post of yours pulled it altogether.

My only question mark would be with the 7mm Rem and 7mm Wby having similar capacity and therefore similar velocity potential.

I think your statement is 100% correct. However, I think the average reloader will be able to have the 7mm Wby running at higher velocity than the 7mm Rem and this is due to the freebore.

Pressure spikes are not so noticeable and powder flexibility is greater.

It is the freebore that allows Wby to have factory ammo loaded to higher pressures. This also applies to the average handloader.

Mike

[ 12-12-2002, 14:47: Message edited by: Mike375 ]

Mike,

You're absolutly correct. The Weatherby's freebored chamber has the effect of increasing the volume of the powder burning chamber, much like increasing case capacity by a slight amount. Weatherby factory loads are adjusted for this freebore, and if fired in a non-freebored chamber may produce undesirably high pressures. This freebore allows the Weatherby to have a very slight potential velocity edge over the Remington. That velocity edge may or may not be apparent, depending on the various qualities of an individual barrel and chamber which effect velocity and pressure.

Jon Sundra has hunted and shot more 7mms than most in the world and started with a Weatherby and also shoots the 7mm Rem Mag. They are by all accounts and by his own admission ballistic twins. The 7mm Rem Mag wins because it doesn't take freeboring to boost velocity, therefore it can be seated much closer to the rifling and thereby it achieves more accurracy on a consistant basis over the Weatherby. The 7mm Rem Mag is also less prone to throat erosion and barrel burn because it has no freeboring, which instigates those conditions. Barrel care is easier for the 7mm Rem Mag.

[ 12-13-2002, 02:03: Message edited by: rossi ]

rossi,

I do not agree with you that throat erosing is more of a problem with freebore, infact it is the other way around. This supported in both theory and in my experience practice.

The reason is quite simple. When you work up your load for the 7mm Rem, the bullet will be quite close to the rifling. Thus a small amount of erosion makes for a much bigger percentage change than is the case with the Wby chamber. In addition, in bench style rifles, you find that calibers like the 7mm Rem and other calibers with similar or greater case capacities for the bore size, need the load changes as erosion occurs. In my experience in bench rifles, the 270 Winchester and 300 Winchester are below a theshold and the 7mm Rem is above the theshold where this occurs.

But I do ageee that accuracy is more fussy with the Wby chamber, although much of this is determined by the diameter of the freebore.

I learnt a long time ago that it is not safe either bet against or bet for a Wby chamber in terms of accuracy.

Mike

Mike 375,

I'll just kindly disagree. Throat erosion is more frequent in freebored chambers and the reason throat erosion is more frequent is due to gas cutting. Freeboring allows hot gases to escape and cut and erode the throat before the bullet actually gets to the rifling. Theres no way with that freebore distance that gas and powder are not harder on both throat and barrel of the Weatherby. The reason I say this is that I owned one at a young age and realized with constant shooting the throat and barrel gave way after 1200 rounds. Being young and somewhat inexperienced at the time, I heated it to much, but I also scubbed it religiously at the range. Don't get me wrong 1200 rounds gets you a lot of hunting, but at that time I liked to shoot alot.

This is only my experience and opinion. By the way I have a 7 Rem Mag now and really think back, and the Remington is just easier to maintain in my opinion, and you gain nothing with the Weatherby over it, except more expensive brass or Weatherby facory loads.

Any good gunsmith will confirm that freebore increases the effect of gas erosion. The majority of experienced smiths will also tell you,they've seen more 7mm rem. mag barrels ruined with cleaning rods,then they ever have from shooting.

I've had seven, 300 win mags over the years. With good care they averaged 2500 rds,before the throats started showing real wear and groups started opening up. With the 7mm rem. mag,you're loading less powder then in 300 mag. In most cases,you're lucky if the 7mag is two or three grains over what an 06 or 270 is loaded to. The result is usually around 4800rds before noticeable wear occurs,when using heavy bullets,like you would with the 300win mag. All of which supports the smiths who have seen more barrel damage in 7mags,from poor cleaning.Then from over shooting.