I love the application of what I have started calling the General Purpose cartridge. It started with the .357 Magnum setup I have with my Marlin 1894 CST, the Taurus 605 Defender and the Remington HTP 158 grain SJHP load. The revolver for defense that meets the FBI testing in ballistic gel with a rifle that can take a deer at 100 yards and do it all from 1 box of ammo.
It has a very practical nature to it but I just can't shake the fact that modern, semi-auto firearms are the norm. I almost never actually carry the Taurus but I do carry my SIG P365XL. I would like to try to duplicate the same capabilities but in modern platforms. A general purpose cartridge for both semi-auto rifle and carry pistol that can take a whitetail from at least 100 yards from the rifle and small enough pistol for concealed carry. All from one box of ammo. The Marlin rifle and Taurus pistol do that but I want it in semi-auto. I will add one more requirement; the guns use the same magazines. Looks like it'll be a Glock. I just need to figure out what cartridge and load to use.
While technically, .357 Mag can be used from a semi-auto, there are very few guns like that. The Coonan .357 is proof that it works but no one makes a semi-auto rifle. I don't care about the Desert Eagle in .357 mag. In this instance, we need to build or select our cartridge for the application. I don't want something proprietary, unless it's .357 Mag Rimless. And no, .357 SIG just is not the same even if Federal's 125 grain HST is impressive.
Below, I go over the direction I would take if I ever get to make this work, however, there are new technologies that are becoming available that have been around a while. After SHOT Show 2025 and specifically Federal's new 7mm Backcountry has come out, I suspect my idea could be rolled up into a brand new cartridge that I will conceptualize below.
Current Options:
I'm open to options such as .45 ACP or .357 SIG but I suspect that a .40 cal will be the best choice. As I do research, 10mm Auto should have the case capacity, pressure rating and commercial support to make this work. There might also be an option for .40 S&W. To make the 10mm work, I will need to test the different loads or find any data available on the internet to see if I can extrapolate. The rifle velocities are the hardest to find.
So far a combination of data from BBTI on the Hornady 200 grain XTP and YouTube videos shows that the 200 grain XTP can do the job. A 16 inch barrel should net around 1260 FPS per BBTI which results in a velocity of 1075 fps around 100 yards. The question that needs answered is if the 200 grain XTP open reliably and penetrate deep enough at a velocity of 1050 fps. Another problem is that Hornady stopped making the 200 grain XTP some time ago. They do still make the 180 grain so that's the most likely starting point.
There are several manufacturers such as Underwood that use the 180 grain XTP and it might be possible to find a factory load that does what I am looking for.
Handloading could achieve this pretty handily. I found a spreadsheet of testing done with 10mm loads using Accurate #9 and 180 grain XTPs. It also has 16 inch barrel data in it. The lowest possible load listed was 12.2 grains of #9. From a rifle, this person says they got 1339 fps from their rifle. This is actually higher than our hypothetical need of 1250. That could give us some wiggle room on the bottom end. That would get us 1088 at 100 yards for the rifle.
Pistol data has been easier to find. The mid 13 grain charges of #9 from full size pistols appear to be 1200 and similar. I would bet those would be very snappy in a little Glock 29. Mid 13 grains would be around 1470 per the spreadsheet. That's more than we need so we could back that down. Comparing the anecdotal data to the Hodgdon Reloading Data Center shows #9 from a 5 inch test barrel is 12.2 gr at 1093 fps and 13.5 gr moving at 1242 fps. That seems to line up nicely.
I won't necessarily run Accurate #9 but it's more of a demonstrator what velocities we can achieve with 10mm and 180 grain XTPs. It also gives us reference levels.
At this point, we need to find a factory load that does as good or better than the 12.2 grain #9 load from a Glock Model 29. I'm choosing the 29 because it's turnkey solution that's easily available. Springfield's XD-M also has an optics ready subcompact, so that's an option but good luck finding a rifle with a magazine to match it. Same goes for the S&W option.
For factory loads, the Hornady Custom (#9126) looks like it could fit the bill.
Finding YouTube videos of gel testing from handguns isn't all that hard to find. Lucky Gunner has testing data that seems to match what TNOutdoors9 found, so we have corroborating data. They even had similar penetration levels of just under 17 inches in gel with denim. That should be enough for deer on a broadside shot.
To answer the previous question of minimum data we have is that 1150 fps is a confirmed good velocity. I don't know if the hypothetical of 1050 fps is valid. The lowest velocity I can find at this time has been 1144 fps from the Hornady load.
Since I can't seem to find rifle data for the Hornady factory load, I think we can extrapolate the 16 barrel velocity. BBTI shows that all the heavier loads are picking up around 200 fps from the 4 inch barrel to the 16 inch barrel. If we take the 1150 fps and add 200 fps, we should be getting around 1350 fps which isn't outside the realm of possibilities based on the numbers seen with BBTI as well as the spreadsheet I found. In fact, that's pretty conservative in the loading The spreadsheet says that would be around 12.5 grains of Accurate #9 with the 180 grain XTP.
At this point, this is starting to look very achievable with commercial, off the shelf stuff. Let's just run that through a calculator just to make sure.
The chart says that with a 1350 fps muzzle velocity from a 16 inch barrel with a BC of 0.164, we are going to see the lowest confirmed velocity of 1144 fps at 75 yards. At 100 yards, we are seeing 1093 fps. I do like that at 60 yards, we're less than 2 inches high with an AR height-over-bore of 2.6 inch zeroed at 100 yards.
Underwood 180 gr XTP is advertised as 1300 fps from a pistol barrel but testing seems to indicate that it's right about the same as the Hornady with common pistols like the G20.
If we use 1150 fps as our hard minimum needed for expansion and penetration, a handload netting 1450 fps from a rifle barrel will get us to that minimum at 100 yards.
Interestingly, if we extrapolate more data from the spreadsheet and compare to the RLDC, 1450 fps would be very close to 13.5 grains of Accurate #9 or so which is the max charge weight.
Simply put, with handloads, this exercise is completely achievable with existing products.
As an aside, I ran through the exercise again but for .357 SIG for fun. I found that the Speer Gold Dot load was used for testing of an Aero Survival Rifle by TNW. They got 1800 fps average or so from the rifle. Lucky Gunner got high 1300's in their testing with 18 inches of penetration in gel from a pistol. I want to note that I spent hours on the above 10mm exercise comparing every shred of data I could find. It's some what annoying that in less than 5 minutes, I was able to confirm that the Speer Gold Dot load can do what we want. The only issue that would need to be confirmed is if .357 SIG at 100 yards is accurate enough for deer. I would also like to note that I think the .40 S&W Federal 180 grain HST, I suspect could be used as well but I need the rifle velocity data and I don't see that anywhere.
I would also like to add that Lucky Gunner did a 100 yard ammo test from handguns years ago. They had a hard time doing it but several of the loads such as the .45 ACP HST and 147 grain 9mm HST opened up and penetrated in the 100 yard target. This would indicate that both the 9mm and 45 ACP cartridges can be used for this roll as well with the correct cartridges.
Future:
What if we took .357 Magnum and stuffed it into a new case that completely duplicated the performance but in a shorter, higher pressure case? A case short enough that we can put it into a modern pistol and high enough pressure to drive a 158 grain bullet to take a deer at 125 yards. I've been wanting to float this idea to a manufacturer for several months now.
Federal released a new cartridge based off of technology that allows for what is considered to be much higher chamber pressure by contemporary standards but still safely operate in what could be considered standard rifles. See 7mm Backcountry.
My thought is what I will call 9mm General Purpose or .357 Automatic. I'm not a ballistian but I'm thinking about taking something like .30 Super Carry and ballooning out the case to 9mm. There might have to be changes to the case length. Increase the chamber pressure. I don't know what we would need to drive a 158 grain bullet out to 100 yards from a 16 inch barrel and still get 1360 FPS. This matches what I get from my current setup. I figure Federal's new case metal would likely be a good choice.
The bullet needs to be engineered so that from whatever handgun launches it still gets enough velocity to achieve FBI standards in ballistic gel from short range and meet and exceed 18 inches in gel at 125 yards.
I'm trying to reach out to a few manufacturers to talk about it and see what comes from it.
Here's the link to the spreadsheet for the 10mm handloads and rifle velocities
https://10mmautocombat.wordpress.com/wp-content/uploads/2013/09/10mm-rifle-data.pdf
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