How much taper from base to shoulder is ideal for a dangerous game cartridge? How "improved" can you make a case and it still feed and extract flawlessly?

Thanks

Holland & Holland did the hard work, so look at the 400 & 465 H&H Magnums. The 404J and 375H&H are fine older examples of well designed cartridges.

he 416 rigby, on the other hand, is also a perfectly designed round, as well as the 308, both of which have a trivial amount of taper.

the lott, which feeds VERY well, as well as the 458 winmag, have about .04 taper (measured from the belt) in a gross view, but in a finite view, it has .023. From the case in front of the belt.

it seems EVERY thing can be made to feed, just depending on how much your smith will do

jeffe

No taper needed. Just proper feeding.

quote:

Originally posted by 500grains:
No taper needed. Just proper feeding.

well said!

I much prefer to use "smooth and enteric coated', since .....

Thanks guys.

I would think the taper would have more to do with extraction. In a dangerous game gun you would want some taper so the case breaks away from the chamber walls quickly and cleanly for reliability. Varmint guns can have straight sided (almost) cases to increase capicity and decrease rear thrust.

Biggest,
taper has something to do with it. but even a straight case in a tapered hole comes right out. I have had ZERO extraction problems, down to .005/inch taper

Why do straight shanked drill bits need clamping chucks and taper shanked drill bits don't? Works for cases in rifle chambers to, or not?

quote:

Originally posted by ScottS:
Why do straight shanked drill bits need clamping chucks and taper shanked drill bits don't? Works for cases in rifle chambers to, or not?

So, what you are talking about in THIS question is actually how the TOOL is held, right?

Which has nothing to do with cases, as the jacobs chunk patent was a tool holding and releasing patent, so one could move away from tapers, as they take forever to realse, compared to chucks.

So, the closest thing in a gun that your straight vs taper on drills comes to is how the casehead is held on bolt.

After all, the twist drill (ou are talking about twist drills, right?) is straight along the twist, ... it's called a reamer or a tapered mill with it's actually tapered.

<sigh>

jeffeosso,

I am not sure if I follow what you are saying. How can you grip a straight shanked drill, end mill, reamer, etc but with a chuck? Morse tapers (and others) rely upon tapered shanks and spindle bores (typically with an additional anti-rotation device) to achieve a lock-up. Ball joints in the front end of your pick-up truck also rely upon taper to taper fits.

So my thought was that if tapers lock and straight walls don't the straighter case may be easier to extract.

Scott,
you don't, unless you a have a milling chuck, EVER mill with a chuck, you use either a tool holder or a collet or a taper on the tool itself.

But, of course, you aren't actually discussing anything, are you? You asked about tapered shank vs straight shank drills.

Morse tapers would never have an "anti-rotation" device, ever ever ever.. a fancy mT has a draw bar,
There COULD be an alignment pin, that is a generally made of key stock, if tehre at all, and NEVER on a morse taper, generally on an R8, but not required



The taper pins in the front end of most cars (we know you are a mechanic, not a machinst) are a cat of another color.. they are not designed to sperate during normal use.

oh welll

jeffeosso,

Didn'r reallize we were talking strictly about torque. Thought we were talking about pull out force. Your mill chuck is a collet, which won't hold an endmill until it has been compressed down. The collet chuck will only grip a staight shank if the straight shank is larger in diameter than the ID of the collet.

It still seems to me that the straight case will have lower extraction force than the tapered case.

BTW, I am not even a mechanic, strictly speaking, since I am not certified.

The information I found was .005 taper per inch of case for reliable extraction.
Take care,
Dave

quote:

Originally posted by ScottS:
Your mill chuck is a collet,.

no, it isn't.

please and learn a little bit about what you are talking about, okay? I recal, as axel, you where a master machinist
http://en.wikipedia.org/wiki/Chuck_%28engineering%29

quote:

It still seems to me that the straight case will have lower extraction force than the tapered case.

no, it's not.

quote:

BTW, I am not even a mechanic, strictly speaking, since I am not certified.

You've stated you are certifed before.

A bmg case has .015 inch taper/ inch length-
A taper pin reamer .011 inch taper per inch-
A 600NE .008 inch taper- Our 12Ga FH case
.005 taper per inch of length.For max loads,
trouble free extraction, with possible heat
caused overloads- .005 is good figure.Ed.

Much obliged. Thank you very much.

Fred Zeglin recommends 0.0075" body taper per inch, more than enough, and that is more than the .404 Jeffery has (.0065" of taper per inch of case body). The .404 Jeffery more than makes up for straight case body with long sloping shoulder (about 8.5 degrees) and long neck.

The .416 Rigby has a lot of body taper (.021" per inch of body) and a sharp shoulder (45 degrees), about as opposite to the .404 Jeffery as can be.

I agree that .005" is the bare minimum allowable taper per inch for any cartridge.

jeffeosso,

If you aren't using a collet chuck on you mill, what are you using a Jacobs? BTW, I never said I was certified, just the opposite. There was another poster here at AR that kept insisting I get my certification (and many believe I am certifiable ). How do the tapered studs on ball joints work if not by taper lock?

the 550 express, 550 mag, 416 ar, 456 ar, and 470 ar use ~ .005/inch, and have no problems.

Tapered ball joint shafts hold due to
the nut being tight holding into taper,
and when nut removed due to taper they can be
pushed or hammered apart due to taper.
And once it moves a small amount it
becomes free on the full shaft length.Not like straight shaft where you have to force it
whole length, and that same principal applies
in a tapered brass case with one added
enhancement- the case springs back a little,
well it's suppose to anyway, and extracter
is able to remove case. Once case moves a minite amount, due to taper it is free its full length. Just like ball joint shaft.They put
steep taper on 50cal because they wanted this
action to move fast and easy in machine guns
with no hesitation.Ed.

quote:

Originally posted by jeffeosso:

quote:

Originally posted by 500grains:
No taper needed. Just proper feeding.

well said!

I agree it was well said, and as it applies to feeding is true. However to say the taper of a case has no effect on feeding is patently wrong. The long tapered case is easier to make feed. Cases like the 416 Rigby can be made to feed properly by a good builder, but it is easier in a CRF action because the round in held in line with the bore of the barrel. with a PF action, it is harder to make feed properly, because the sharp shoulder, the cartridge lying in the loading port un-attended while being pushed forward.

contrary to what some say, taper has far more to do with extraction of a case than feeding. This is especially true in rifles like double rifles, or break top single shots, where extraction camming is less than in a bolt rifle.

A case in point here is the Ackley Improved rounds like the 30-30 AI, when compared to the factory 30-30 Win. The increase in velocity of the AI version was not the only benefit of this design. The experiments to see if the old mod 94 could work OK with the 30-30 AI, which produced chamber pressures/ and velocity equal to the 308 Win. The locking lugs where removed
from the 94, and fired with the AI, and the rifle remained closed. The 30-30 Win opened it every time. The reason this happened is because the straight sides case, to the shoulder, in the AI, gripped the walls of the chamber, enough to negate ther reverse thrust of the case. The tapered case in the 30-30 win, did not.

This gripping of the case walls to the chamber walls in adverse conditions, it the reason the long taper was designed into the 375 H&H case at a time when cordite was causeing extraction problems in hot climates. Today this same effect happens in rainy/humid climates, with un-plated cases, causeing the case to glue it's self to the chamber walls. The taper lets the the case free odf the chamber walls with only .001" od rearward movement, or less, but the surface area of a straight sided case has far more gripping area to break free, and must move farther rearward.

Taper does matter, be assured of that! Maybe not a problem all the time but more so than some think!

My experience is about the same as the few others here who have actual first hand knowledge of the effects of case taper. .005/inch results in both slick feeding and easy extraction. On a few wildcats I've gone .001 and it still worked fine in a bolt gun of course! I believe that at the moment of firing a case with a large amount of taper will stick/grip to the chamber walls quite strongly minimizing head thrust which is probably a very good thing in double rifles. Of course the brass then springs back about .003 making for easy extraction. The one exception is of course the hated soft Bertram brass which sticks like hell and does not contract well. In a bolt gun, I don't think it matters much. THEY CAN AND DO TOLERATE much higher levels of bolt thrust than a double will. The reason the 12gaFH and .600OK have minimal taper was to achieve max case capacity. Both feed and extract flawlessly with working pressures of 65 Kpsi.