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PRESSURE, VELOCITY AND THE 444 MARLIN

BY BILL MCCONNELL 

 

This tech notes is all about pressure. The cartridge I am focusing in on is the 444 Marlin in the Marlin 1895. As the pressure on any brass cartridge case is increased, the brass case will expand enough to measure and offer us a look at the pressure the case just went through in the process of being fired. With this knowledge and the ability to measure the expansion on a brass case, we can evaluate powders, primers, & bullets as to how they affect the maximum pressure of a load in a certain firearm. Add in a chronograph & target and most of the secrets a cartridge holds can be revealed. So let’s get started.  

The first 2 things we need are a micrometer that accurately measures down to the nearest .0001 and the ability to use it. I am no expert on micrometers. I do know that before his retirement, my father was quite an excellent machinist. He also built, tested and launched satellites for a living. If you look in his tool drawers, his micrometers mostly stay Starrett on them. By the way, we are definitely not talking about vernier calipers here. They are not precise down to .0001 (one ten thousandth of an inch). Using the micrometers is not very tough though it’s best to be shown how before you dive in. A little reminder from my father. The micrometers and brass should be the same temperature every time you measure with them. Unless you are a really good machinist, your readings of such a small measure will likely not be the same as somebody else’s. That’s ok as long as you do all your own readings and they are repeatable. 

The part of the case we want to measure is the part just forward of the rim. We are looking for the maximum diameter of the case just ahead of the rim. When you measure circular objects this precisely, things are rarely exactly round. That means you’ll have to rotate the case to find the maximum diameter. That is what you are measuring for. There is not space here to go into the greatest of detail. If you do some research you can find the process described in great detail. 

Rather than get bogged down early on, let me give you an example. Take a 444 Marlin with a 290gr Beartooth bullet. Three loads are listed below. All use the same powder, primers and brass. The only difference is the amount of powder. The crimp column tells you if the bullet was roll crimped with the seating die or if it was “Factory Crimped”, with a Lee Factory Crimp die.  

 

BUL WGT	MANUF	TYPE	PMR	CASE	LOA	POWDER	WGT	MV	ES	CRIMP	CHE
290	B TOOTH	LFNGC	WW	REM	2.57	H-322	52	2084	19	FACT	0.4671
290	B TOOTH	LFNGC	WW	REM	2.57	H-322	53	2138	17	FACT	0.4685
290	B TOOTH	LFNGC	WW	REM	2.57	H-322	54	2158	19	FACT	0.4686

Now look at the far right column. It says CHE and that is short for case head expansion. Notice that when the weight of powder goes up, the expansion of the case increases. The velocity went up. The pressure went up though not necessarily in a linear fashion.  

It is a challenge to make sure our results are not a lie. As many things as possible must be kept as a constant. All the primers are the same from the same lot. All the brass is from the same lot, trimmed the same, resized but unfired. All of the powder in each test is from the same lot. All the bullets are the same diameter & same alloy from the same source. If you were trying to measure the difference in primers, you’d leave everything the same except the primer. Remember, these tests are all done with brand new resized brass.  

Right about now you may be wondering, “What is the actual pressure of your loads?” I do not know. The method I choose was to compare pressures (CHE) from known and proven loads in similar firearms to establish a baseline of what personal working and max pressures should be. More specifically, what I did was to recreate Marshall Stanton’s famous load of 56.0gr of H-335 with his 330gr bullet. See the results below; 

 

BUL WGT	MANUF	TYPE	PMR	CASE	LOA	POWDER	WGT	MV	ES	CRIMP	CHE
330	B TOOTH	LMNGC	WW	REM	2.57	H-335	56	2066	13	FACT	0.4689
330	B TOOTH	LMNGC	WW	REM	2.57	H-335	54	1994	37	FACT	0.4679

 

Now Marshall has been shooting this load in his Marlin rifles for over 20 years with great success and no pressure problems. That was my starting point. I am somewhat conservative in my loading so I tried a slightly lighter load with 54.0 gr of H-335. For a slight velocity drop, I got a major drop in pressure. So now the pressure standard was developed to be around .4680 in case head expansion. As always, this number is based on an average of 5 cases measured. A single case measurement will really get you in trouble. In over 2 years of using this standard with my Marlin Outfitter the brass stretches very little and the primer pockets are as tight as when it was new. No case has ever failed either. This does not mean the 56.0 gr load is over max. Not at all. Remember, I do not know what the actual pressure is.  

All this information is very accurate and repeatable in my rifle. The nature of firearms is they vary quite a bit for pressure accuracy etc. In other word, do not go by my numbers. They are sure to give you problems. You can, however, develop the data yourself for your firearm and get great results.  

Ok, let’s get back to the fun. We have established I like to run a case head expansion of around .4680. This is for moderate temperature testing around 50-80 degrees. Extreme heat or cold can negatively change pressures so keep things as constant as possible.  

 

Watch how we can tell what results we get with different powders.  

BUL WGT	MANUF	TYPE	PMR	CASE	LOA	POWDER	WGT	MV	ES	CRIMP	CHE
290	B TOOTH	LFNGC	WW	REM	2.57	H-322	52	2084	19	FACT	0.4671
290	B TOOTH	LFNGC	WW	REM	2.57	H-322	53	2138	17	FACT	0.4685
290	B TOOTH	LFNGC	WW	REM	2.57	H-322	54	2158	19	FACT	0.4686
290	B TOOTH	LFNGC	WW	REM	2.57	H-335	57	2018	25	FACT	0.4652
290	B TOOTH	LFNGC	WW	REM	2.57	H-335	58	2056	40	FACT	0.4672
290	B TOOTH	LFNGC	WW	REM	2.57	RE-7	52.5	2250	24	FACT	0.4677
290	B TOOTH	LFNGC	WW	REM	2.57	RE-7	53	2273	50	FACT	0.4681
290	B TOOTH	LFNGC	WW	REM	2.57	RE-7	54	2325	26	FACT	0.4687
290	B TOOTH	LFNGC	WW	REM	2.57	AA-2230	55	2030	64	FACT	0.4662

Do you see any trends here? Yeah, at least in my rifle, RE-7 is the rocket. For a case head expansion of .4681, 53gr of RE-7 gave me 2273 fps. At roughly the same pressure, H-322 powder gave me 150 fps less velocity. H-335 gave me, well, a lot less velocity. The problem was I simply could not get enough powder in the case to boost velocities and pressures up to their potential. I had the same problem with AA-2230. This, by the way, is always a consideration in the 444. With a lot of powder/bullet combinations, very compressed powder charges will result. That is not bad. It is challenging for the reloader as cast bullets will sometimes back out of the case before the Factory Crimp can be applied.  

 

Want to try a different type of bullet? Rock Island Ballistics makes a 265 gr bullet for the Marlin 1894. Though It’s not designed for the 444, I gave it a ballistic whirl. 

BUL WGT	MANUF	TYPE	PMR	CASE	LOA	POWDER	WGT	MV	ES	CRIMP	CHE
265	ROCK IS	TCWGC	WW	REM	2.47	H-4198	47	2146	26	FACT	0.4672
265	ROCK IS	TCWGC	WW	REM	2.47	H-4198	48	2195	20	FACT	.4680.
265	ROCK IS	TCWGC	WW	REM	2.47	H-4198	49	2247	22	FACT	0.4685
265	ROCK IS	TCWGC	WW	REM	2.47	RE-7	52	2299	3	FACT	0.4678
265	ROCK IS	TCWGC	WW	REM	2.47	RE-7	53	2338	35	FACT	0.4681
265	ROCK IS	TCWGC	WW	REM	2.47	H-322	54	2191	60	FACT	0.4677
265	ROCK IS	TCWGC	WW	REM	2.47	H-322	55	2248	30	FACT	0.4682

 

I have changed a couple of the powders due to the lighter bullet weight. Notice again that RE-7 is the rocket here. H-4198 is about 100 fps behind for the same pressure. H-322 is closer with a loss of only 70 fps or so. The reason I choose to test this specific bullet is that, when seated to the optimum depth, it takes up exactly the same amount of space in the case as the preceding 290gr Beartooth bullet. Notice that with RE-7, the max loads and pressures are very close. Velocities are greater with the lighter bullet but powder vs. pressure is pretty close. In three decades of reloading straight walled cases I have found the depth a bullet intrudes into a case is nearly as important as the bullet weight itself. One of the very remarkable aspects of Beartooth bullets they are denser than any other cast bullet I ever bought. That is, a heavier bullet in less space. In cartridges like the 444, that means more velocity, less pressure, easier loading or a mix of all three. The LBT LFN design is easily the ultimate bullet for the 444 if you are looking for the max velocity and flattest trajectory per grain of bullet. However, sometimes range is not so much an issue but giving the animal a big slap with a large meplat bullet. The big meplat forces more bullet into the case by virtue of its design (shorter nose). These are bullets like the TCW tested above and most of the LBT WFN designs. Yeah, you’ll lose some potential velocity but if you’re hunting something in the brush that’s hairy and toothy, the extra slap comes in handy. By the way, the Rock Island bullet is well made and shot very well all the way out to 200 yards. 

 
This is a good time to look at some heavier bullets. Let’s try some 330 and 320gr bullets.

BUL WGT	MANUF	TYPE	PMR	CASE	LOA	POWDER	WGT	MV	ES	CRIMP	CHE
330	B TOOTH	LMNGC	WW	REM	2.57	H-335	56	2066	13	FACT	0.4689
330	B TOOTH	LMNGC	WW	REM	2.57	H-335	54	1994	37	FACT	0.4679
330	B TOOTH	LMNGC	WW	REM	2.57	H-322	50	2073	29	FACT	0.4995
330	B TOOTH	LMNGC	WW	REM	2.57	H-322	48	1996	21	FACT	0.4682
BUL WGT	MANUF	TYPE	PMR	CASE	LOA	POWDER	WGT	MV	ES	CRIMP	CHE
320	CASTPER	WFNGC	WW	REM	2.54	H-322	48	1949	30	FACT	0.4674
320	CASTPER	WFNGC	WW	REM	2.54	H-322	48	1966	39	ROLL	0.4676
320	CASTPER	WFNGC	WW	REM	2.54	H-322	49	1992	19	ROLL	.4680.

This is where I started a few years ago with the 444. I just love those big heavy bullets. Knowing the pressure gives us more freedom to pick powders. Though H-335 is THE great powder with this 330gr Beartooth bullet, I wanted to match the pressures without all the hassle of very compressed powder charges. I also wanted to use a Hodgon Extreme powder. Enter H-322. Compare the 54.0 gr load of H-335 and the 48gr load of H-322. In this case I traded a small increase in pressure for much easier loading of the cartridge with almost no powder compression. The 48.0 gr. load of H-322 has proven to be amazingly accurate and consistent out to 200 yards. With the porting on the Outfitter, recoil is not an issue. Now look at this twist. The load with 50 gr of H-322 appeared to have the same pressure as the 48.0 gr load. No change in primers or extraction. Still , the 50.0 gr load is way over my established maximum pressure limit.  

Next we look at the 320gr Cast Performance bullet. It’s the first bullet shown that actually has a crimp groove that is meant to be used in the 444 Marlin. The 2 loads that use 48gr of H-322 differ in only one way. One is roll crimped from the seating/crimping die and the other is Factory Crimped with a Lee Factory Crimp. Though the difference is smaller with heavier bullets, the Factory Crimp typically gives less pressure and a lower extreme spread. The bottom 320 gr load is known as “The Coles Load”. It’s named after the close friend I developed the load for. Like my favorite 330 gr load, it gives a lot of performance & accuracy with minimal powder compression but also adds the simplicity of a roll crimp. Most of the Beartooth WFN design bullets also allow a roll crimp in the crimp grove.  

None of this matters if we cannot hit the target. I take all loads that interest me to the range for shooting at 100 and 200 yards. Those targets go in my record book right with the other testing data. In my experience, good data and good accuracy go together about 80% of the time.  

Well, we have covered a lot of ground here. I hope you have seen something that will benefit you in your reloading and shooting. Normally I am somewhat hesitant to publish loads. My results have been perfectly safe for me but that does not mean your results with my loads will do as well or even be safe. Something as simple as a change in primer or lot number of powder can change things for the worse. Please follow all prudent rules in reloading and work up slowly testing for pressure and safety. I have no background in Winchester rifles chambered in 444 Marlin.

Truth be known, the 444 Marlin is just a 44 mag that grew up. It will shoot lead balls @ 600 fps just for the fun it. It will shoot 240gr lead bullets @ 1300 fps for inexpensive plinking fun. It will also shoot a Beartooth 250gr LFNGC at around 2700 fps out of my little 18 ½” barrel. It will shoot the big bruiser 330 gr bullets @ 2000 fps with great accuracy. I think the most versatile bullet for the 444 is the Beartooth 290gr LFNGC bullet. Out of the 18 ½” barrel is easily hits 2250 to 2300 fps and is quite accurate. It really is the “mouse to moose” rifle of our times. Not perfect for everything but perfect for many things and pretty good for most of the rest in big game hunting. Well, it might be a little short on legs for those 350 yard shots.  

Have fun, be safe and burn some powder! 

 

Bill McConnell

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