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.
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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.
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.