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Discussion Starter #1
Hello everyone,

I have a few questions regarding cartridge design. For ease of reading I will just list them. If it matters at all, the rifle would be a Winchester 94.
(1.) What are the pros and cons to wall taper, and what is the max and min ratio.

(2.) How does shoulder profile affect back thrust?

(3.) What is the minimun neck length? does this vary depending on bullet type?

(4.) How does bore diameter affect pressure?

I am planning on building and "improved" in either 25-35, or 30-30, maybe 35/30-30 and wanted to get a better understanding of the physics and engineering behind the "improvment" <!--emo&:)--><img src="http://beartoothbullets.com/iB_html/non-cgi/emoticons/smile.gif" border="0" valign="absmiddle" alt=':)'><!--endemo-->
Thanks Much
Juan
 

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Hello Juan!...I will attempt to answer your questions. Yuo are already on the right track, with the important factors to consider whether you are building a wildcat or selecting one.
1 The wall taper is very important especially in lever guns. The flater the wall taper the less back thrust to the bolt. Parker Ackley proved this. Besides increasing the powder capacity the reduced wall taper reduce case stretch. Two of the worst case designs for bolt thrust and strecth are the .348 Winchester and .280 Ross.
2. Shoulder profile is more important in powder burn and throat erosion than anything else. The flatter the wall taper and sharper the shoulder angle, the less the powder will be "funneled" into the front of the case as pressure rises. Some designers believe that there is a plug of powder blown into the barrel burning and the sides burn in the case. Another advantage of the sharps shoulders is, the angle that white hot powder particles intersect inside of the case, instead of the throat. This redues throar erosion.
3. The neck of the design should be long enough to cover all the lube grooves and base of hard cast bullets! If this is not done, no real accuracy will ever happen. On jacketed bullets the base should always be ahead or at the junction of the neck and shoulder. Ifnot, and is down in the powder, you have reduced powder capacity.
4. With all things being equal...case capacity, case shape, powder type and weight, bullet weight, and pressure..the larger base area of the bullet, since the gas has more area to work on, will be ay a higher velocity. Of course the shorter fatter bullet my not have as good a BC. Both wildcats you mentioned are excellent, but my nod would be to Ackley's .30-30 Improved.With it's reduced bolt thrust aand improved case capacity, it performs far beyond the standard .30-30. With its long neck, it is ideal for cast bullets.
I hope this answered some of your questions...Best Regards, James

(Edited by James Gates at 10:57 pm on Feb. 27, 2001)
 

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Discussion Starter #3
James,

Thank you for the information! It seems my pseudo wildcat project has taken a turn, however a forward one. A wildcat that I had thought of earlier, but put on the back burner was a 35/30-30, or something similar.

Today I picked up an octagon barrel for my 94. I have not yet slugged the bore, but it is stamped 357 max (maximum?) Thge length is 20", and it is nickel steel, so pre-war? At any rate, I suspect it was a 25-35 or 30-30 barrel to begin with. I am guessing it was shortened at both ends, to provided the proper size to be able to cut a chamber for the 357 max. At any rate, it clocks up perfectly on my receiver, and the dove tails, are in great shape. With this comes more questions for you, so here we go again <!--emo&:)--><img src="http://beartoothbullets.com/iB_html/non-cgi/emoticons/smile.gif" border="0" valign="absmiddle" alt=':)'><!--endemo-->

1. Depending on the bore size, which I have not slugged, is it safe to interchange 357 pistol, and 358 rifle bullets, or are the .358 jacket bullets too tight in a .357 bore?

2. Have you ever played with, or read anything regarding a 35/30-30 or similar? I have also read about a 357 bullbery, which seems to be a "ackley improved" style 35/30-30. This is what I am really leaning toward if I can find more info on it.

3. Would you estimate case volume would be in the league of the 35 Remington?

4. Rate if twist min and max?

As before, thank you very much for your insight!

Adios
Juan
 

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Juan...I'm at a loss on the barrel? It sounds like a rebore job to me. I think I would make cast of that chamber to find out just what it is. Some where in the back of my mind I seem to remember that the Mod 92 threads were the same as the Mod 94...I'd have to check that. Some one may have set it up for a 92. Be sure and check that since the rim is much smaller on the .357 Max than the .30-30. There would be a lot of trouble on the cartridge cutoff out of the mag tube on the 94.
As for the .35/.30-30. I have not work with that one so I'll pass to Marshall. I think he has worked with it. I do under stand it's a little hotter than the .35 Remington. Sorry I could not help more!
Best Regards, James
 

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Juan, from your two above posts, I think P.O. Ackley's books 1 and 2, as well as "Cartridges of the World" are appropriate.

But on barrel bore diameter and pressure, I can calculate the stress on the steel in the barrel.
The thin wall hoop stress is directly devirable:
The inside diameter  times the pressure is the force, and the thickness
of two walls are in tension, hence:
Steel stress R = [ID][P]/[[2][wall thickness]]
The stress to break off the barrel like a lizard's tail is:
Steel stess L = [ID][P]/[2][pi][wall thickness]
This is why pressure failed barrels always fail lengthwise and never radially.


To be correct for thick walls, I have to mention Lame.
When the walls are thin, Lame's Formula gives the same answer, but as
the walls get thicker, Lame's
formula gives an increasingly  greater stress.

I got Lame's formula from "Mechanics of Materials"  by Laurson and Cox,
1938 Wiley and Sons.
The derivation was first done the the French mathematician, Lame, 500
years ago. It is a difficult derivation.
If the barrel is thick, read an two inches further down my post to Lame's formula:



S=P(r2 squared +r1 squared)/(r2 squared - r1 squared)

Where S is the stress in psi of tension

P is the chamber pressure in psi

r1 is radius of the chamber or bore in inches

r2 is radius of the barrel [center to outside] in inches"
 

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Juan,

Before any modifications are done, you should thoroughly consider one question-

What do you want to do with this gun that can't be acheived with an existing cartridge?

Wildcats can be interesting, but if they were really an improvement some arms maker would've adopted them. After all, if they can't sell "new and improved" they're out of business. The only ones that made the cut, so to speak, were the .257 Roberts, 25-06 and .35 Whelen. Two of the three are barely alive today in a commercial sense, regardless of the fact they are excellent and useful rounds.

There really is nothing at all wrong with a standard .30-30 or .35 Remington. In fact with today's bullets, propellants, and stronger brass they are much better cartridges than when introduced.
 

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No reason minimum case taper should reduce case stretch. What reduces case stretch is having a case that fits the chamber snugly in the first place with minimum headspace.

There is no case in the world strong enough to resist the pressures of a modern rifle. If there is any headspace and the front end of the case seizes the chamber the case base will set back regardless of case taper.
 

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Most of the wildcats you are refering to have been done...a long time ago.

The 35-30-30 was done for old 30-30 that were shot out; reream the barrel to 35 keeping the chamber. It is not as powerful as the 35 rem, but close.

25-35 improves are also old as is the 7mm-30-30 (aka 7mm waters). there are also many 30-30 improved or wildcat cases.

Not sure what you want? nor why you want it..but seems an expensive thing to work on when most of these have been done.

You might want to get RCBS ballistic program that includes a cartridge designer section. You can design any case diemension and it calculates the case volume A Powley calculator or Quickload can give you estimated velocities.
 

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I know it's close to Easter, but

Hi Bagtic and Harry,
This thread is from 2001. IMO, so much water has flowed beneath the Winchester bridge, since 2001, that this needs a new O.P.. Face it, Winchester's Model 94 is history. The new Japanese number is probably made on metric machinery, and is too expensive to mess with.

I'd say it's time to start leaving the American Winchesters alone. I'm left handed, and the later cross bolt safeties, and angle ejectors, aren't my cup of tea. I'd say that for all our twentieth century rear locking lever action rifles and carbines, it is now an exercise in "keeping them running". For me, that means buying a couple of boxes of factory ammo a year for each and every one that I have.

Especially for the M-71 in 34Win., if no one buys a yearly box of ammunition, for each one, and shoots it up, then it's a gone gosling. That's my beef with these "collectors" who have a whole rack of Em!


And for a parting shot, to this 11 year old thread, even the late Mr. Johnson, up at Coopers Landing, AK., admitted that it would have been better to simply neck up a 348 Win. case to .458, and leave the rest of it alone. And his 50 AK, started out it's life, as a 50-110 Win. Express. So, except for fitting in the modern 348 Win cartridge casing, it was still a stock action, with a new barrel screwed in, and with some re-enforcing of it's magazine tube.
 

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I only have one original M71....but I never buy ammo. I reload!

Wild West Guns anchorage is making the 450 Alaskan on the 336 marlin frame. I shot one when up there, nice guns....I'd not convert my 348. But the co-pilot is a nice thing.
 

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My wildcat...

Posted just for grins. Have everything but the barrel, which is expected to be delivered around June 1. Rifle is at gunsmith's-- waiting...

 

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Designing a cartridge

For the Win. 94, I am curious if the bolthead and the magazine tube could be opened up slightly to accept the 220 swift case as a higher pressure alternative to the much weaker 30-30 win. This could creat a slighly better platform for a creative wildcat, but even 30-30 necked down to 223 or 204 might be interesting/
 

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Most of the wildcats you are refering to have been done...a long time ago.

The 35-30-30 was done for old 30-30 that were shot out; reream the barrel to 35 keeping the chamber. It is not as powerful as the 35 rem, but close.

.....
Yep, Got to agree With Harry - Looking at the 30/30 and the 35 Rem, your not going to get that 30/30 case up to the capacity of the 35 Rem.

You open to another case to start?
 

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. . .even .30-30 necked down to .223 ... might be interesting.
I've thought of this, too. Imagine such a chambering in a T/C Encore (mine is presently chambered for .223 Rem) to see if it would shoot worth a hoot. If it did, the next step is a bolt-action thang and it's off to the races. 'Bout all you'd have to do is have the reamer, headspace gauges, forming and reloading dies made, form/trim the brass to the same length as the .222 Remington Magnum (1.850 inches) to be cutting the leade on fresh steel, find a really good gunsmith and acquire tons o' patience as you wait for it all to come together. Come to think of it, that's about all you have to do for just about any wildcat...
 

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N.V. Shooter, Those volumes seem awfully high to me. My 2.6" Boer 8mm Mag. made with the Ruger Basic brass equals the 300 Win Mag, necked up to 8mm, and is right at what you are claiming for one with the neck removed.

And your 30-06 Magnum must be very close to the 300 RCM's volume. Back about 79, Blount experimented with Aluminum Blazer ammo for thirty thirtys. They found many of the "try" model 94's and Marlins, had developed way too much head space, for these brittle cases. I think you need to look at excessive head space, also.

A rimmed brass case can alibi a whole bunch of slop. But your ideas and the Blount Blazers, won't. You also have to have a bullet available for your tubular magazine, before you have a barrel re-cut. The new Miroku model 94's are in 30-30, and 38-55. I don't care for any of these, as I am left handed, and I hate looking down the cut away side rail, and seeing the yellow glint of the brass case head.

So, right now, the only new top ejector, is the larger M-71 in 348 Win.. And the only M-71 which will fit into a Pickup cab's gun rack, is the earlier Browning carbine version. Either the flat nosed bullets don't have the range, or they kick way too much. Now if some ammo company decided to make a gummy pointed, boat tailed bullet, 348 Round, out of a lead free material, it may give the old slumbering 348 some new legs. Until then, this old thumper will remain a lever action 34-06, in striking energy, and trajectory. I did a powley computer scan and got 2850 fps, and 3050 ft.lbs. for a 170 grain homogenous bullet, with the same length as the 200 grain lead ones. But with a gummy tip, and boat tail, it would solve some of the factory ammo's trajectory deficiencies.

Interestingly, I don't see either the thirty thirty, nor the Three Oh' Seven, hanging with it. Of course the BLR, has options which will surpass all of these. But don't get between a lefty and his Winchesters.
 

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I've thought of this, too. Imagine such a chambering in a T/C Encore (mine is presently chambered for .223 Rem) to see if it would shoot worth a hoot. If it did, the next step is a bolt-action thang and it's off to the races. 'Bout all you'd have to do is have the reamer, headspace gauges, forming and reloading dies made, form/trim the brass to the same length as the .222 Remington Magnum (1.850 inches) to be cutting the leade on fresh steel, find a really good gunsmith and acquire tons o' patience as you wait for it all to come together. Come to think of it, that's about all you have to do for just about any wildcat...
This one is close to what you are looking at.
22 Savage High Power
 

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My mildcat is a REALITY!!

I ain't gonna retype all this stuff, or Copy and Paste it. It's a long post over at ammoguide. It's the one from July 15 at 0058 EDT. It's on Page 3 of the "Barrel manufacturer..." thread. I hope you can see what I wrote if you are not members. I am pretty sure you will see X for any number used in the posts if you are not a member. No matter-- I didn't need to use that many. Today's load was 60-61 grains of WC852 and bullet was the 160-grain Hornady FTX. Everything else written there should come through...

AmmoGuide Interactive Forum
 

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Wildcat using .30-30 brass necked to .224

This one is close to what you are looking at.
22 Savage High Power
Looked at it on ammoguide's cartridge diagram thingy. Neck is w-a-a-y too long and shoulder angle is way too steep. I'd shorten the neck to 1.15-1.25X of caliber and put the shoulder angle at 22-24 degrees. This would have the thing lookin' more like a modern cartridge that uses smokeless power instead of some 19th Century thing usin' cordite, black powder or whatever type of stuff they used back then. I know smokeless powders came along about 1895 or so, but many guns were not strong enough to use it. Thus, the low-pressure powders they used before smokeless gained widespread popularity hung on for quite a while. But I could be wrong...
 

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Looked at it on ammoguide's cartridge diagram thingy. Neck is w-a-a-y too long and shoulder angle is way too steep. I'd shorten the neck to 1.15-1.25X of caliber and put the shoulder angle at 22-24 degrees. This would have the thing lookin' more like a modern cartridge that uses smokeless power instead of some 19th Century thing usin' cordite, black powder or whatever type of stuff they used back then. I know smokeless powders came along about 1895 or so, but many guns were not strong enough to use it. Thus, the low-pressure powders they used before smokeless gained widespread popularity hung on for quite a while. But I could be wrong...
Here is some interesting info on the 22 high power loads.
5.6x52R and .22 Savage High-Power

http://www.reloadersnest.com/frontpage.asp?CaliberID=20
 

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NVshooter
the 30-30 necked down has been done with the 25-35 being necked down to 22 it was in fact a commerical cartridge up untill about 1960. Marlin chamber the 336 lever gun in the 219 Zipper. It is the 219 Zipper, which was then also wildcatted into the WASP, and later even a Donaldson WASP.

the 219 had a great reputation for accuracy, and was used in many bench rest competitions. Local gun shows often have a few 2 inch dia barreld rifles in the Zipper (often old Krags done before WW-2).
 
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