Spike Camp

7mm Weatherby

7mm Weatherby
« on: September 09, 2011, 07:04:09 AM »
It seems like we talk a lot about the .257, .300, .270, 30-378 & 338-378 Weatherby cartridges, but don't mention the 7mm much. What's the deal? Is it because it is so close to the 7mm Rem, that we go with the less expensive option? Or is it because there are better options in the Weatherby lineup. I think it was dubyam that mentioned that the 270 shoots bullets of the same weight faster than the 7. A general understanding of rifles and physics tells me that doesn't make sense. Do cases not get more efficient as the mouth gets wider? I would like to see some real data from guys who know how to reload and own a chronograph. I ignore factory numbers most of the time. I would say a handful of rifles in each of the calibers would give a reasonable sampling. I know some of you guys out there have experience and, for sure, an opinion.
Isaac

Re: 7mm Weatherby
« Reply #1 on: September 09, 2011, 07:10:36 AM »
In reading my post a second time it occured to me that I was implying a few things that I certainly did not mean to. I am not trying to call duby out, nor am I saying that he is wrong about the 270 being faster than the 7mm. It may indeed be the case. I was also not trying to say that he doesn't know how to reload and has not already compared the 2 cartridges over a chrony. Just asking a few questions based on a comment that I thought was made by him. Just want to clarify!
Isaac

Re: 7mm Weatherby
« Reply #2 on: September 09, 2011, 07:33:25 AM »
At one time I had a Mark V Stainless in 270 Weatherby Mag and also one in 7MM Weatherby Mag. I still have the 7MM. The 270 is gone. The performance of the two was very close but IMO the 7MM is more versatile. I don't really miss the 270 that much. ;D

Re: 7mm Weatherby
« Reply #3 on: September 09, 2011, 08:13:49 AM »
Actually, W said, "the 270Wby...will deliver 130gr bullets faster than the 7mmWby will deliver the equal-weight-for-caliber 140gr bullets by about 100fps."  I'm not surprised that a comparable case shoots a lighter bullet faster than a heavier one.

BTW, since the 7RM and the 7Wby cases are comparable, I wonder if the 7RM can be safely loaded to match the 7Wby.


Re: 7mm Weatherby
« Reply #4 on: September 09, 2011, 08:15:43 AM »
To clarify the case/mouth comment. I was trying to state that the 7 should be more efficient than the 270, i.e the 30-06 is more efficient than the 25-06 or 300 Win more efficient than the 264 Win.
Isaac

Re: 7mm Weatherby
« Reply #5 on: September 09, 2011, 08:21:34 AM »
You don't buy a Weatherby Magnum because it's efficient. You buy it for performance and SPEED! 8)

Chip

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Re: 7mm Weatherby
« Reply #6 on: September 09, 2011, 09:11:10 AM »
There isn't a dimes worth of difference between the two when fired out of equal length barrels.  However there probably is a nickles worth of difference that gives
the edge ever so slightly to the Weatherby in terms of velocity. The freebore and the fact that a lot of Weatherby's have 26 inch barrels helps to push it ahead. The freebore is what makes the difference by allowing for hotter loads.  I shoot a 7 Rem Mag out of a 26 inch barrel attached to an Accumark and I think I have the best of both worlds really.   I don't see how a guy could go wrong with any 7mm myself.  I never met one i didn't like.

Re: 7mm Weatherby
« Reply #7 on: September 09, 2011, 09:58:17 AM »
I've read about "freebore"; however, I gotta say, that concept baffles me.  As releated to accuracy (which Wby touts), most of the accuracy stuff I've read talks about seating close to the lands.  As related to velocity (which Wby touts),  I've read plenty of places that the way to increase velocity on a straight-wall case is with a heavy crimp.   

I don't know about this "freebore" concept -- is is just more marketing hooey?

Re: 7mm Weatherby
« Reply #8 on: September 09, 2011, 10:44:24 AM »
aka: I don't think it's just marketing hype. Take a look at the 7mm Rem and 7mm WBY. The last time I looked, I think one of my reloading manuals actually stated that the Rem has a hair more case capacity than the Weatherby. Now it may be that the WBY can use more of that case capacity because of it's longer neck, or it could be that it has some room to accelerate before hitting the rifling. Weatheby's have an excellent reputation for accuracy as well.
Isaac

Chip

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Re: 7mm Weatherby
« Reply #9 on: September 09, 2011, 12:00:37 PM »
A heavy crimp on a straight wall case is going to be determined more by the powder you are using than anything else.  If you load up H110 in your 44 mag with a 240 or 300 gr bullet you are going to need a heavy crimp for a couple of reasons.
One is that if you don't put a heavy crimp on it and that bullet gets to the forcing cone before it should it can act like a bore obstruction and really bad things will be happening in short order. The second is it keeps those bullets in place under that heavy recoil. I don't think it's going to get you any big velocity increases with light target loads of say W-231 with 205gr semi wadcutter.  Freebore as I understand it changes the pressure curve and allows for a little hotter load.  As for accuracy I have seen some pretty tiny little groups posted in here coming out of freebored chambers.It doesn't seem to be hurting it very much.

zonie

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Re: 7mm Weatherby
« Reply #10 on: September 09, 2011, 12:31:07 PM »
Isaac: テつ I know what you are getting at, and I agree with you in the broader sense, テつ  but there are other considerations to look at. テつ Efficient may not be the best word to use. テつ Maybe a better way would be to say a 30-06 will shoot a 150 gr bullet faster than a 270 winchester using the same bullet and that would be true in this example, and it's probably going to use more powder or different types more suitable for the increased dia. テつ  テつ I probably wouldn't use the 264 vs 300 win mag, テつ the 300 win is a longer case with more volume テつ it's really not a fair comparison. テつ  Even if the cases were almost identical using the same parent brass, neck lengths, shoulder length, taper, etc, テつ  Anytime you open a bottle neck cartridge up to a larger dia, テつ given mid range bullets weights the larger dia will almost always shoot faster. テつ I'm not talking comparing テつ a 243 case vs a 358 win that's a bad example, テつ but cases that are somewhat closer together in dia. テつ  テつ I didn't use powders as an example because some cartridges can have テつ wide acceptable charge weight テつ variations when comparing. テつ  テつ 

Heavy crimps do in fact change and can increase ツ velocities in certain circumstances. ツ About the only time you need a heavy crimp is on heavy bullet revolver loads to keep the bullet from backing out or heavy large bore calibers using very heavy bullets. ツ Military uses them but they are multi-purpose rounds to be used in bolt actions to machine guns. The only time I crimp is on ツ 223's, 30-30's with cannelures, ツ heavy revolver loads and the 458 win mag. ツ 

Most of the time the 7mm rem mag from the factory is downloaded under what it's actually capable of. ツ The freebore on Weatherby rifles is to allow running pretty much full throttle and still keeping within acceptable pressures. ツ  Factory WBY uses powder blends ツ not available to us for this reason so they can keep the velocities just a little above. ツ It does work and not hype. ツ 

I would say overall your best accuracy is close to the lands, ツ BUT not in all cases. ツ The factories don't do it for liability issues and variations in how the rifle's chamber is actually cut. ツ  It definately increases pressures when you jam into the rifling. ツ Barnes recommends .050 off the lands as a starting point. ツ Berger recommends 0, .040, .080 and .120 off the lands to find a sweet spot. ツ Every rifle bullet combo shoots different so the idea of a very specific seating depth is kind of hit and miss. ツ This is something when handloading you just need to test and find out just how far it needs to be, and that's bullet specific, once you change bullets all bets are off. ツ There are a certain few calibers where seating depths are so well tested the 308 for example using 168's it's almost hard to beat, ツ it's possible but awfully hard. ツ 

eford

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Re: 7mm Weatherby
« Reply #11 on: September 09, 2011, 12:47:53 PM »
When it comes $$ for ammo, the 7mm Rem Mag beats the 7mm Wby Mag. Guys who occassionally hunt might only buy three boxes of ammo a year are more likely to get the lower priced stuff, and we know Weatherby factory ammo is not cheap even though you get good stuff.
In my opinion, the 7mm Wby is between two great ones, the 270 Wby and the 300 Wby. It's sort of the strange cousin, even though it is an "old Weatherby" chambering when compared to the 340 or the 416.  Any thing a 300 Wby can take can also be taken with a 7mm Wby. It all comes down to shot placement.
I will admit if I had to choose only one Wby chambered rifle it wouln't be the 7mm Wby, but if you gave me one I sure wouldn't turn it down. Oddly enough, there is a 7mm Rem Mag Accumark with a built-in muzzle break in a store for only $750, but I'm taking a pass on it since I have others that can do the job. Timing is everything.
My son uses a 7mm Rem Mag Vanguard Sporter and he shoots it as well as anyone else can. I'll be surprised if he gets anything larger for a while, but the 7mm sure does a great job on white tails, and so does the ordinary 270 Win. Someday, I'll probably end up with a decent 7mm mag, and it is nice to have a lot of choices out there.
« Last Edit: September 09, 2011, 01:02:31 PM by eford »
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Re: 7mm Weatherby
« Reply #12 on: September 09, 2011, 01:22:47 PM »
The 7mmwbymag in my humble opinion is the best all round wby caliber for NA game except for giant brown bears, and even then its enough but not the best choice. It flattens everything from moose to mice. Some would argue the 300wby but it packs quite a bit more recoil. It is such a good caliber Remington more or less copied it some years after it came out taking advantage of Wby's proprietary standing. Imitation is flattery. Is it better than the Rem? Not really but it sure is a sexy looking cartridge. Mine has hunted for two generations and in all those years never has a second shot been needed.

I know this isn't a scientific explanation, just a passionate one. 270Wby would be my second choice for all round NA caliber.

James
exhale and squeeze

Re: 7mm Weatherby
« Reply #13 on: September 09, 2011, 02:28:25 PM »
Of course I have to weight in on this thread, since the 7mm is my favorite caliber for larger game. Its a very, very cabable caliber for almost anything in N. America, but more pleasant to shoot as far as recoil than a 300. it,s so close to a 270 Wthby mag there really isnt any difference, even the rem mag is close enough to both in reality you wouldnt know any difference out in the field. For as much as I like to shoot I have Rem mags, I would like a 7mm wthby mag for my collection, in a really nice wood gun ( Lazermark, Euromark, Deluxe hmm...).
Troy

Re: 7mm Weatherby
« Reply #14 on: September 09, 2011, 02:39:22 PM »
Unless I am reading the charts wrong the 7MM Weatherby is head and shoulders above the 7 MM Remi as far as ballistics, James sorry but from moose to mice it has to be the 257 ;)
Terry
Ontario,Canada........yours to discover