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Lately I've been kicking around some ideas for a pair of wildcats for Marlin Lever Action rifles quite a bit. The idea is to use the .338 Marlin Express as a the basis for a larger cartridge that just surpasses the .348 Winchester and a smaller cartridge that's more focused on the kind of deer hunting that I think is done throughout most of the country.

I'm going to start with the smaller cartridge, which for lack of a better name I've dubbed the .250 Marlin Express. The basic idea is to make a cartridge that fits a handy Marlin lever action that is capable of killing deer out to 4 or 500 yards. I'm basing a lot of my ideas for what loads would look like on both the .250 Savage and the .338 Marlin Express. Loaded with a 200 grain bullet, the .338 Marlin Express uses 47.5 grains of Leverevolution powder to get a velocity around 2500 fps. This results in a pressure of around 46,000 PSI. The .250 Savage uses a 35 grain dose of CFE 223 to push a 100 grain bullet to about 2900 FPS at 44,400 CUP. So that comes out to a 12.5 grain difference using similarly rated powders. In fact the two powders are so similar that they are listed as #105 and #106 on Hodgdon's list of powders by burn rate.

My idea for this cartridge is to use a similar shaped bullet to the one used by the .308 or .338 Marlin Express cartridges that weighs 110 grains, and push it with a 40ish grain charge of either of the powders listed above. Without quickload, my guess is that this would allow for a muzzle velocity that's similar to that of the 100 grain load for the .250 Savage, but with a much higher BC and more weight than is available for the .250 Savage.

Based on this, I've come up with a theoretical ballistics chart (200 yard zero), using the BC for the Nosler 110 grain Accubond (.418) which is as follows:
Range Velocity Energy Trajectory Come Up (MOA) Come Up (MILS) Wind Drift Wind Drift (MOA) Wind Drift (MILS)
0 2900 2054.0 -2.5 0.0 0.0 0 0 0
100 2679 1753.0 1.2 -1.1 -0.3 0 0 0
200 2468 1488.0 0.0 0.0 0.0 0 0 0
300 2267 1256.0 -6.9 2.2 0.6 0 0 0
400 2076 1052.0 -20.6 4.9 1.4 0 0 0
500 1894 876.0 -42.4 8.1 2.4 0 0 0

I think this is a little optimistic given a 48,000 PSI limit personally, but I'd be really interested in hearing what other posters think about this idea for a gummy tipped small bore round.

~
My other idea revolving around the .338 Marlin Express case is to neck it up to .375 for a true Alaskan cartridge. Again, the working title is something simple like .375 Marlin Express.

So based on the aforementioned .338 ME loads, my idea for the .375 is to have 3 loads available that would cover a wide amount of game. For a general purpose load, I think a 250 grain FTX would fit the bill well for one major reason; it has an extremely similar section density (.254) to that of the 200 grain loading used in the .338 ME (which has an SD of .250). To me this makes sense as a conjectural baseline because the two bullets are likely to be of similar lengths, or the .375 could be even shorter than the .338 bullet. Not being a ballistic engineer, this of course is merely conjecture but seems pretty sound based on my research of .338 and .375 bullets with similar SDs.

Anyways, by using a 250 grain bullet with a wider base my hope is to grab onto what I can only describe as the .35 Whelen effect, when similar weighted bullets are fired in cases of similar capacities, usually the wider diameter bullet sees an increase in velocity. Using this as an example, using H4895 an 180 grain bullet out of a Whelen gains about 7% more velocity than a .30-06 with the same bullet weight. Using a similar ratio, we can surmise that the .375 Marlin Express could push that 250 grain FTX bullet to about 2400 FPS with the powders available to handloaders. This gives it a solid 16% increase in energy to 250 grain .338 ME factory loads once available through Remington, and puts it at the top level of energy available to the venerable old .348 Winchester.

Of my other two loads I've thought up for this cartridge, the other one that I think deserves mention is one that uses a 270 grain Woodleigh Weldcore round nose bullet. With a very short bullet length of 1.08" I feel like this bullet could be seated in a very advantageous way even in the short fat .338 ME casing, with a muzzle velocity likely between 2250 and 2350 FPS. Again, this puts it just above common loads for the .348, while the presence of a bullet with the dangerous game pedigree of the Woodleigh Weldcore makes me certain this would be great bear medicine.

Thanks for reading this guys. I'm interested in what people with a little bit more experience with wildcatting think of these ideas, in particular the theoretical ballistic figures I've listed.
 

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I'm sure the 338 ME case has been necked up and down, exactly as you have stated. I'm also sure both calibers you chose would be excellent wildcats.

The problem is the parent brass you chose is already difficult to find and WILL dry up, completely, at some point. The 338 ME is loosely based no the 376 Steyr and cannot be easily made from any other brass.

You would be just as well off to get a series of forming dies and neck down a 45/70 to both .375" and .257". You could also go with the very fine 375 and 257 JDJ cases (based on the 444 Marlin and 225 Winchester, respectively). While brass for the JDJ cases isn't always easy to find, it's likely there will always be seasonal runs of both parent brass, due to the number of factory rifles originally sold and the number of wildcats already using them. I honestly don't think the 338 ME will ever achieve either of those milestones.

See also 25-35 Tomcat (AI) and 375 Express - non-proprietary options for the above. It's ALL been done.

With all of that said, if your pockets are deep, go for it.
 

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I think Broom_Jm makes some good points.
I note that your velocity/drop table is with a pointed Nosler Accubond bullet. You won't be able to use more than 1 cartridge at a time in a tube magazine like the Marlin. Seems to me that any attempt to make a 3-400 yard rifle out of a 336 or 94 is going to be futile because of the need to use flat point bullets in a tube magazine, unless you restrict yourself to Hornady FTX bullets.
 

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There is a reason bolt action rifles are preferred for long range shooting. :)

You can make a sports car out of a dump truck if you have the money to do so, but you wont have a sports car at the end of the money, only something 'different'. "Different" is easy to do. ;)

If you want a 25 caliber lever action find and old Savage 99 in 250-3000.
 
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I think Broom_Jm makes some good points.
I note that your velocity/drop table is with a pointed Nosler Accubond bullet. You won't be able to use more than 1 cartridge at a time in a tube magazine like the Marlin. Seems to me that any attempt to make a 3-400 yard rifle out of a 336 or 94 is going to be futile because of the need to use flat point bullets in a tube magazine, unless you restrict yourself to Hornady FTX bullets.
Yeah the idea was to go with an ftx bullet. You're absolutely right though, with the accubond I would have been restricted to 2 shots.

I'm sure the 338 ME case has been necked up and down, exactly as you have stated. I'm also sure both calibers you chose would be excellent wildcats.

The problem is the parent brass you chose is already difficult to find and WILL dry up, completely, at some point. The 338 ME is loosely based no the 376 Steyr and cannot be easily made from any other brass.

You would be just as well off to get a series of forming dies and neck down a 45/70 to both .375" and .257". You could also go with the very fine 375 and 257 JDJ cases (based on the 444 Marlin and 225 Winchester, respectively). While brass for the JDJ cases isn't always easy to find, it's likely there will always be seasonal runs of both parent brass, due to the number of factory rifles originally sold and the number of wildcats already using them. I honestly don't think the 338 ME will ever achieve either of those milestones.

See also 25-35 Tomcat (AI) and 375 Express - non-proprietary options for the above. It's ALL been done.
My issue with the 25-35 AI is that I don't think it can be as accurate as a 338 ME based cartridge would be. The 308 and 338 ME cartridges use the same shoulder shape and body taper as the 6.5 CM or at least extremely similar to it (they were all designed by Hornady around the same time). There'es a pretty proven advantage to short fat powder columns that I think could be taken advantage of in a lever gun,

The .45-70 point is extremely valid though. In fact the .38-56 AI is what had come up with the basis for the .375 express on. My thought though was that with the smaller rim diameter of the .338 ME you might be able to use a 336 as your starting point instead of the 1895 and save some modification time to the mag tube and barrel bands.
 

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There is NO accuracy advantage in case shape, only disadvantages from a headspacing and feeding point of view.
Capacity equals performance. Headspace, feeding and extraction are the only other parameters to consider....and maybe extra work sorting out the VERY BEST 30-30 brass, which Steve Herrett did for years.
 

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There is NO accuracy advantage in case shape, only disadvantages from a headspacing and feeding point of view.
Capacity equals performance. Headspace, feeding and extraction are the only other parameters to consider....and maybe extra work sorting out the VERY BEST 30-30 brass, which Steve Herrett did for years.
I find this a bit odd, since everyone since P.O. Ackley has said that short fat powder columns produce more efficient burn rates and takes out the variables that can lead to innacuracy. I understand that any rifle cartridge, using well designed loads and good components can achieve more than decent levels of accuracy, but I've always thought it was pretty securely noted that short fat cases produce less variable results.
 

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They say it, but can they prove it? Two different things.

The bench rest crowd is pretty adamant about what works (for good reason). But the difference between first, and way down in the also-rans, might be a few thousandths in the aggregate. Important for them? Yes. Deer hunters? Not so much.

An interesting experiment would be to take a barrel, and chamber it to something with a long skinny case in that bore size. Shoot for groups off of a machine rest or the like, then start rechambering it in cartridges that are progressively shorter and fatter, but the same case capacity. Shoot for groups again, repeat till you run out of money ;)

If you don't use the same barrel, then it isn't a direct comparison. I realize that you can get enough data points from different rifles to start to sort it out, but it takes a LOT of data to really get confidence in the answers. A sample size of two rifles? Forget it. Flip a coin.....
 

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Granted---A column of 40 grains of powder in a straight walled case is NOT as effecient as a .243.
You said "Accuracy". Case shape is about number 88 on the 100 most important things needed for accuracy.
If three cartridges are the same bore diameter, same capacity and fit the same action, there will be no difference in 'inherent accuracy' between them. They might be case life problems, extraction problems (too straight) or feeding problems but 'inherent accuracy' is not dependent on case shape otherwise.
 
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Oh by the way, my dad chambered a Marlin 336 in .250 Savage. Why? Because he wanted to ;)

Staying away from max load, it works great, and has accounted for several deer. Does it have any great advantage over a Savage 99? Not really, except you can put a 1-10" barrel on it, whereas the 99s seem to be in the neighborhood of 15" or so inch twist. They were allegedly 14" twists, but mine was slower than that, as other writers have mentioned in the gun press (Barsness, I think).

Anyway.... it can be done, if you want to go that route. Up to you. Max case capacity, as mentioned, would be with a .45-70 or maybe a .450 Marlin parent case.
 

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An interesting experiment would be to take a barrel, and chamber it to something with a long skinny case in that bore size. Shoot for groups off of a machine rest or the like, then start rechambering it in cartridges that are progressively shorter and fatter, but the same case capacity. Shoot for groups again, repeat till you run out of money.
That was done 50 years ago!! Warren Page was the shooter in some of the experiments. There is a definite relationship between the shape and size of the primer flash and the length and diameter of the powder column, but the shape of the case has effect on brass but not accuracy.

Some cases have a reputation for being very easy to load for, like the .270 and anything built on a 7x57 case and some are known to be very particular over what powders they'll burn correctly. The .284 Winchester comes to mind.

Think of 'accuracy potential' as a big pile of bricks of different sizes. The big ones on the bottom (Straight, Solid and Square) gives an MOA with most barrels. As the bricks are stacked higher, it gets more complicated and to put little bitty bricks (caliber shape) on the bottom and then build up is counter-intuitive to one that builds rifles.
 

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repeat till you run out of money
Wildcatters and BR shooters are most often gunsmith/machinist.
 
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I think it has been overdo for a small bore lever action cartridge. The bigger bores are fun, I like my 338MX and 356 win for deer hunting. But my son has been shooting whitetails just fine with his 260 Rem. Ballistic tipped bullets make big nasty holes in game. So a 25 caliber levergun with newer style bullets sounds great to me.

Pressure is what you need to get velocity. A 338MX case has way more capacity than needed to acheive your results. To have 250 savage results in a tube mag levergun would be great. A 100 grain ballistic tip will kill deer and a 1 in 10 inch twist works great. Start going much heavier you will need a tighter twist to get good accuracy. I know the 250 savage and the 25-35 AI have the same case capacity. But the 25-35 AI doesn't feed in a lever action very well with it's straight wall and sharp shoulder. We do know that the Wincheste 307 and 356 case shape does feed in Marlin actions. So I would suggest looking at a 307 case necked down to 25 caliber. Do you calculations using the 25 Souper and see what results you get at the pressures you are trying to achieve. If the case is too long to accept the length bullets you want then push back the shoulder, maybe the same length as the 250 savage, but keep the same body taper and shoulder angle as the 307 and you will know it will feed. Plus brass is not hard to find.

I think a 375 caliber on 338mX would also be fun. I have thought of this before, but my experience with the 338MX and 356 Win. is that it hammers whitetail and I don't need a bigger hammer. But it still would be cool to have one. So start with the 25 caliber wildcat and I would like to hear the results.
 

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A true 1-10" barrel will easily stabilize 117gr. - 120gr. bullets. I've known people with .25 cal cartridges that couldn't shoot bullets that heavy, but none of them actually measured the twist rate in their guns. There's no telling what it could have been.

I have a .250 Savage on a mauser action with a 1-10" twist, a .257 Roberts on a 10 3/8" twist, and a .257 Weatherby with a 1-10.1" twist. All will stabilize bullets in that range, and yield deer-killing accuracy as far out as I have any desire to shoot one.

Agreed, easiest way to get a neat .25 cal wildcat on a Marlin lever gun would be to neck down the .307 Win to .25 cal, and put a barrel that is at least as fast as 1-10" on it. That would be an updated version of the .250 Savage and ought to kill deer like poison ;)

In my opinion/experience .....
 

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Agreed, easiest way to get a neat .25 cal wildcat on a Marlin lever gun would be to neck down the .307 Win to .25 cal, and put a barrel that is at least as fast as 1-10" on it. That would be an updated version of the .250 Savage and ought to kill deer like poison ;)

In my opinion/experience .....
Do you think the .307 or the .308 ME would be better? The .308 has a shorter case length (1.91) and should accomodate a higher BC bullet like an FTX better than the .307 case (2.015") within the 2.55" OAL required on a 94 or 336.
 

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Do you think the .307 or the .308 ME would be better? The .308 has a shorter case length (1.91) and should accomodate a higher BC bullet like an FTX better than the .307 case (2.015") within the 2.55" OAL required on a 94 or 336.
The 308 Marlin Express is a 307 Winchester case with the shoulder moved back and the rim diameter reduced. It has less capacity.

With all due respect, chasing long-range accuracy from a lever-action rifle is a bit of a fool's errand. You've got numerous options already available, in the form of Savage and Browning actions chambered in relatively modern rounds using pointed bullets. The problem is the lock-up of a lever-action rifle just isn't favorable for delivering the sub-MOA accuracy one would ideally have if you're going to shoot them at ranges well beyond 300 yards.

Forget about the idea of the lever-action and go with a strong single-shot or bolt action. You'll have lots of great options that will be a lot easier (and less expensive) to achieve. Enjoy lever-action rifles for what they are and don't ask them to become long-range tack drivers.
 

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Kevin, from what I am reading you are not looking for a tack driver but a round that will kill a deer at 400- 500 yards. Leverguns are funny things, some I have shoot Ok , plenty good for deer. Then I do have a few that shoot MOA and have no problem hitting steel at 400 yards. So I don't see a problem building a small bore levergun cartridge to do what you are asking. Building and testing is the fun part. If that is your passion go for it. Read McPhearson's book on Accurizing the Factory Rifle and he has tips for leverguns.

I think necking down the 308 MX would get you what you are looking for. When Marlin came out with the 308MX I was hopeing the next thing they did was to neck it down to 25 cal.
 

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.25" cal wildcat

Kevin H. -

Howdy !

A .35Rem necked-down to .25" caliber would have case capacity > a .250 Savage,
and < a .250Savage AI.

The new Hornady .25" cal 110gr ELD-X deserves a look... especially if looking to maximize energy retention.

A comparatively long(er ) barrel would help boost achievable Mv.

It might make sense to go w/ a slower powder than what might typically be used, and keep load density towards the higher side. A less temp sensitive such as H4350, IMR4451 or even perhaps
IMR4955 would be great to have, should Mv look good to you.

I happen to have a case forming die set that takes .35 Rem down to ( amongst other things )
a .25" caliber version...... along w/ an easy-to-form 26* shoulder angle.


With regards,
.357Mag
 
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