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Discussion Starter #1
Do all the Weatherby cartridges incorporate the same degree steep shoulder?  Are there any drawbacks to the shoulder's nearly perpendicular form?  It would seem there may be some feeding issues, but I've never heard of a Mark V having any sort of feeding problems.  Am just curious and was wondering why only Weatherby uses this if it increases case capacity, even the AI's are more sloped, aren't they around 24 degrees?  Just curious.
 

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alyeska 338, howdy. first i do not own a weatherby, never have. but have heard enough owners say they have problems crushing shoulders while sizing , that i dont want one. some weatherby owners say they just turn the sizing die up 1 full turn and this solves their problem. as far as the A.I. MOST but not all shoulders are 40 degrees. again i don't have one. BUT i certainly have looked at their drawings. they are very interesting in their effeciency. by the way if it does'nt rain all day tomorrow i will get to shoot the 458 wm for the first time. i was still not able to get the factory loads. but all my gear came in that little brown truck. thanks to marshall, i was able to get some load data for 450 gn hardcast with xmp-5744. thanks marshall. if all goes well, i will let you all know how it went. halfbreed
 

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Discussion Starter #3
Thanks halfbreed.  You are probably right on the AI's, I wasn't sure and trying to recall that off the top of my head while at the office.

It's been a long 2 weeks of having a rifle you can't shoot hasn't it?  That would have drove me nuts.  Thought you might have been holding out me.  <!--emo&;)--><img src="http://beartoothbullets.com/iB_html/non-cgi/emoticons/wink.gif" border="0" valign="absmiddle" alt=';)'><!--endemo-->

Let us know how it shoots, several folks have inquired about the CZ, though I think yours is the only 458!!!
 

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I've had considerable experience with the AI cartridges over the years, and have them from .223 AI to .375 H&H AI and a smattering of others in-between.  My experience has shown, with these, like the Weatherby cartridges that best results are obtained when only neck sizing.  Brass life is longer, accuracy is better and you only have to lube the necks this way!

As far as feeding goes, a few of those guns I've rechambered to AI's necessitated working over the feed rails for best feeing reliability, but never had any problems once they were properly adjusted for the nearly straight AI cartridges.

One particular advantage both to the AI's and Wbys is that there is virtually no case stretch as when compared to other "conventional" cartridges.  Brass life is much better in my experience, and incipient case head separations are few and far between.

FWIW

God Bless,

Marshall
 

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Discussion Starter #5
Thanks Marshall and halfbreed.  It's my understanding that the steeper the shoulder the higher the pressure created, all else being equal, because more powder is burned inside the case before the bullet begins it's journey?  Supposedly, the near perpendicular shoulder of the Wby "traps" more gas and increases pressure.  I don't think trap is the word I'm looking for, but hopefully gives the right impression, like a sharp bend in a creek.  I've read in other places that the more sloped shoulders allow gases an easier path to be channeled, but more powder is burned over a longer period of time, relatively speaking.  If it is real, is it a real concern?  Can the interrupted gas flow cause a much larger spike in the pressure curve when when all other parameters are kept equal, or is it splitting hairs?



<!--EDIT|alyeska338|April 20 2002,12:40-->
 

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Alyeska,
   The Weatherby shoulders are not actually in degrees, they are measured by the radius of two circles, one centered on the edge of the cartridge case, one on the neck. I don't know specific numbers for the sizes of the circles but it would have to vary for eack different sized case. I read that the idea was for the rounded shoulder to create a more efficient burning and flow of the gasses and have thus heard the shoulder called a venturi shoulder. It seems that the steepness of the AI shoulders achieves the same goal.     IDShooter
 

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Discussion Starter #7
ID,
Sorry about the edit to the previous post, I was doing that at the same time you were adding your post and did not any way mean to question you...  I just can't type fast enough.  Sorry no offense and did not mean to question you at all.
 

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Alyeska,
   It's interesting to compare the Weatherby shoulder to the AI shoulder. Instinctively I doubt if there is a real difference at all, but I don't know of any published tests comparing them.
    You know, I'm amazed at some of the theories that I would like to see tested but there just doesn't seem to be much real data out there. I know it's economics; the only reason anybody spends a big chunk of money on that type of research is if they can sell something. But wouldn't you love to see a test of two (or more) cartridges, equal in capacity and bore size, but with differing shoulders. Load them to equal pressure in the same dimensioned test barrels and see what they do? Are there differences in velocity? Charge weights required to achieve a given pressure? Consistency? Throat erosion? Case life? The list goes on and on.
      I would also like to see this type of test done on some of the Ackley cartridges, but loaded to the exact same pressures as the parent cartridge in test barrels with equal specifications. I suspect much of the gain from AI cartridges is from loading to higher pressures in the altered guns, but I would love to KNOW.
     Another test I would like to see run - In a given case, say 30-06, which powders caused the most throat erosion provided all were loaded to the same pressure? Slow powders? Fast Powders? Ball powders? Granular powders? Is erosion based on the quantity of powder used or the burn temp? I think it's pretty well established that very high pressures and very large cartridge to bore ratios cause a lot of erosion, but have never seen a published test like the one I describe.
       I know it would cost lots of $ but I would love do those kinds of tests.          ID

Sorry to get off topic. It just occured to me that so much in this hobby is speculation or at best, comparing apples to oranges.
 

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Discussion Starter #9
ID,
Yessir, I would love to see those tests.  Actually the reason for my initiation of this thread is I'm trying to pick a wildcat for the 1895 Winchester.  Pressure seems like it might be of concern.  The 411 Hawk, the 400 Brown-Whelen, and 2 or 3 other 400 Whelen Improved's all have different shoulders and, from the data I can gather, significantly different ballistics.  All using the same case, different shoulders and somewhat differing capacities.  My concern is that a steeper shoulder (which seem to have the better ballistics by a significant margin) create much higher pressures that help to achieve the extra velocity.  If that pressure spike is above what is max operating pressure for the 95 (it is a new rifle, not an original), I'm afraid I may have a new boat anchor.  I know the various Whelen Improveds work well in bolt actions (even non controlled feeding actions) so I'm not too concerned about the headspacing, but I am concerned about the pressures.  If it is negligble, I would go with something like the 40 degree AI shoulder or even a Wby shoulder, however if those pressures are 10,000 units higher, I don't think I want to do that.  Any ideas?

Looking at the cartridge, there's not much of a shoulder to start with, so I don't think it would have the same effect as an overbore type cartridge.  When Col. Whelen first designed the 400, there were terrible headspace issues because he kept the '06 shoulder angle.  Since then several have overcome the headspace issue successfully by incorporating steeper shoulders.  However the only data I can find for a non bolt gun is Z-hat's 411 Hawk in the 1895.  The Hawk has about 10-15% less velocity than the others and the others having shorter barrels. If I could better a 26" barreled Hawk performance from a 22" barreled other '06 wildcat, I think that is a significant improvement.  4" inches of barrel in the alder thickets is something I would like to leave at home.  However, there just isn't more than an article or two about any of them and we all know how "optimistic" some of the first tests of a new cartridge can be, I'm really really confused.
 

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alyeska338,

An easy way of conceptualizing the role of the shoulders on the '06 based .40 and .41 cartridges is to simply think of the shoulder as a forward positioned belt. These shoulder are so small that I can not see them having any influence beyond headspacing. The velocity differences are probably more a factor of the targeted pressure for each round, and the body taper of the various versions than any difference in these tiny shouders.

Since you brought the Weatherbys into this I will add to the confusion by noting that you could make a straight cased .416 for your '95 by using the .240. This round would have nearly the same dimensions as my .416 TAS except for length. Headspacing on the belt allows the increased bullet diameter to.416 for a larger selection of bullets. Let's call this "The Alyeska Stalker".

Fireplug
 

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Alyeska,
     I would be willing to bet that the other rounds you're reading about acheive higher velocities than the Z-Hat round only through being loaded to higher pressures. I can't prove it, but I believe it until it's proven otherwise. I just don't think such small variations on the shoulder angle, especially on such a small shoulder to begin with, would greatly affect ballistics. This is 100% pure speculation and opinion on my part. Man I wish someone would run those tests!!   ID
 

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Along with other important facts that I have collected over time (such as the main journal measurements of a 1984 volvo 2.3), I thought the BR guys had gone thru a lot of shoulder angles in the 40s and 50s (AIs heyday)?  

The results seemed to be that various shoulder angles, all else equal, created minor, if immeasurable, improvements to accuracy.  Other design parameters seem to have more effect and contribution to accuracy and performance and shoulder angle seems to be driven by (rather than deciding) the other factors (feeding, base diameter, volume, OAL, headspacing, etc.)

As proprietary cartridges, reloading probably isn't a concern for Weatherby or his target customers.  Most of the guys that bought Roy's guns bought them so that they wouldn't have to think about that piece of equipment.  That may be changing with the new Weatherby, but the origins are still visible.

Regards,

Charlie
 

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Discussion Starter #13
ID,
That is my suspicion also.  I didn't really notice any difference in powder flavors, but the BW's had a healthier charge (none were compressed).  I'll run some IMR charges on the Powley Computer and try to come up with some pressures.  Sure wish Kronfeld had some testing done on his.  With the 1895 not having any loading cavaets against the Hornady Light Magnum in the 270 and '06, I'm wondering if it's an issue or not.

Fireplug, you are right that is worth looking into, Thanks...

Charlie,
Yeah, I think a lot of folks have played around with the 40's.  I've seen the 411 Hawk, the 400 BW, and 3 different shoulders for the 400 Whelen Improved.
By the way, this is all your fault, you know that don't you?  <!--emo&;)--><img src="http://beartoothbullets.com/iB_html/non-cgi/emoticons/wink.gif" border="0" valign="absmiddle" alt=';)'><!--endemo-->
 

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Ideas are cheap.  Making it work is the tricky part.

Wondering about an extended .41 mag case - like Marlin/Rem did with the .44 mag-to-.444 Marlin... There's not much diff (.02) between the .44 and .41 though to make it worth the bother(?) for a 200yd any-deer levergun.

Regards,

Charlie
 

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Charlie,
You aren't talking me into anymore messes!!!  <!--emo&;)--><img src="http://beartoothbullets.com/iB_html/non-cgi/emoticons/wink.gif" border="0" valign="absmiddle" alt=';)'><!--endemo-->  I've got my hands full with this suggestion you gave me.
 
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