bottleneck cartridges - different form, different performance?

[simonrichter]

A general question concerning bottlenecked ammunition: Is there any correlation between the form of a bottleneck cartridge and its performance? What I mean is when you have a cartridge of one given caliber and internal volume, you could either make it long and slim (like, say, a .22 wmr), or slightly bottlenecked (like a .223) or quite fat on the bottom (like 6mm PPC). A last possible variation would be conical, of course.

Would there be any difference in terms of the internal ballistics and performance or is it merely a matter of sizing / mag feeding etc.?

[Bart B.]

It's pretty well established that shorter, fatter cases for a with sharper shoulder angles and longer necks for a given caliber produce both better accuracy and longer barrel lives.

There are, of course, exceptions, but the above's a pretty good rule of thumb.

[Doyle]

Bart has it right. That is part of the reason for the recent increase in the number of short and super short magnums. Greater velocity with less powder due to a more efficient burn.

[simonrichter]

ah, I see. There has never been one single question not satisfactory answered in this forum!

So they only reason why not going super short and fatty is magazine stacking, I reckon?

[jmr40]

If you get carried away with too short and too fat feeding can become an issue as can mag capacity. Some of the 1st WSM guns had a few issues until manufacturers figured it out. Part of the reason for the WSSM's failing is due to feeding issues.

[Bart B.]

There was a very popular bolt action rifle that when offered in .308 Win., those shorter, fatter cases didn't feed as reliably as the more tapered bodies on the .30-06, .270 Win and .25-06. I don't know if Remington ever fixed that problem with their Model 700's and 40X's.

[reynolds357]

Short and fat is supposed to be more accurate than skinny and long. Brass definitely lasts longer on the fat boys. I remember reading something one of the designers of Safari rifles wrote about 70 or 80 years ago. He said the only reason they put so much taper on the cartridges was to assure that the cases would not stick in the double rifles when fired on extremely hot days. Dont know how true that is, but it sounds logical to me.

[old roper]

There is two types of accuracy one is a factory rifle which most own others are the custom.

If you build a 300WSM for hunting then build a 300mag or 30-06 accuracy be the same. If you look at a match rifle build in 300WSM it's fired single shot most times build on single shot action.

No question some of the WSM use less powder but there very limited in bullet selection due to the magazine length.

Lot of the short cases are great just with one type bullet so there always trade-off's.

[JerryM]

Personally I do not care for the short, fat cartridges. A major reason is the reduced magazine capacity, but I admit I have never used one.

If you are a hunter and not a competition shooter the barrel life should not be a problem. I never worried about barrel life. By the time I would wear the barrel out I would have spent much more for ammo even if handloads.

Jerry

[jimbob86]

If you are a hunter and not a competition shooter the barrel life should not be a problem.

That depends upon whether or not you shoot the rifle you hunt with much.

Of all the rifles I have, the one I shoot most should be the one I hunt with, and vice versa ....

[coldbeer]

So the Weatherby double radius shoulder design is more efficient than that of say a 300 win mag? I always thought Weatherby cartridges were all about case capacity but it looks like Mr. Weatherby did his homework.

[44 AMP]

I remember reading something one of the designers of Safari rifles wrote about 70 or 80 years ago. He said the only reason they put so much taper on the cartridges was to assure that the cases would not stick in the double rifles when fired on extremely hot days.

This is basically true. If you look at all the classic African "stopper" cartridges, they all have fairly long tapered shapes. The designers knew what was needed to work in Sub Saharan Africa. None of them are high pressure rounds. Even when you get to bolt guns, the cartridge design philosophy remained long and slender for some time.

Benchrest shooters showed the way, shorter, fatter powder columns do overall, provide better accuracy. Very important in winning a match. Fairly important when shooting varmits and other precision uses.

Not very critical when the main task is stopping an upset buffalo at 15 yards.
Unless the shorter fatter round doesn't feed or extract well, then at 15yds, it would be hyper critical!

[old roper]

There lot of case in short yardage BR that are not SAAMI spec 6ppc,30Br and others. F-Class open is the 284 Shehane and if you look at the 284 it's long throated and your getting 2900fps appr with 180gr bullets. Also your not going to wallk in and buy ammo for them.

[Kimbercommander]

Some people hate the .300 win mag for some reason or another. I dont know I dont reload. However I can hit a 15" steel plate at 1k with it all day long. I think the manufacturing companies are just trying gimicks to get peoples money from them anymore. Just my two cents. However I am probably wrong.
I had me one of those 243 WSSM's and i hated it i could never find ammo for the stupid thing. So i traded it off for a few SKS's.

[Mobuck]

This subject is the basis of some VERY heated arguments among the wildcatters. In some cases, it's more like a woman's looks-some are attractive in different ways.

[Bart B.]

Regarding case extracting issues with 375 and larger caliber cases from chambers in British dangerous game rifles a century ago, they all had a few ten-thousandth inch or more clearance from the chamber walls and needed little force to pull the fired cases out. That was/is assured by peak pressures being less than 40,000 cup, not case design.

Some magnum Mauser actions were deep enough to extend below the stock half an inch or so to hold more fat cartridges. The steel in the rifles wasn't as strong an hard a modern rifles but made intricate detailed engraving much easier.

[James K]

I am sure all the above is accurate and that the posters are truthful.

But I still think there are a bunch of guys at the gun/cartridge companies who sit around and say things like, "What kind of silly gun/cartridge can we come up with this month to get the gunzines all excited and convince the people out there that they absolutely have to have the new whatever?

Jim

[jimbob86]

But I still think there are a bunch of guys at the gun/cartridge companies who sit around and say things like, "What kind of silly gun/cartridge can we come up with this month to get the gunzines all excited and convince the people out there that they absolutely have to have the new whatever?

Such is the business: they are making tools that oftentimes take lifetimes to wear out .... they must create a need, for if they waited for a genuine, need, they's go broke!