[Walt45]

We can all pretty much agree that the 45-70 and 450 Marlin are basically the same cartridge out of a marlin rifle. Now for the question:
The Hornady Handbook 8th edition lists the 45-70 with a 300gr bullet at 2000 fps with 52.3gr of RL-7 from a 22 inch barrel (Max load). However the 450 Marlin is listed at 2200 fps with 57.1gr of RL-7, shooting the same 300gr bullet from a 18 1/2 inch barrel . What is the difference between the two guns/cartridges that accounts for justifying the extra powder capacity safely?

 

[Mainspring]

"Capacity" might be the wrong term. I don't have the 8th Edition handy, but look at the guns used for load development, they may be different. The factory deems a load "safe" with the exact components and gun used for testing, and those items must be safe to begin with, no loose-as-a-goose rifles etc..

In addition, there are no old factory rifles chambered for the .450 Marlin, they are all using modern materials and modern metallurgy. On the other hand, the .45-70 Gov't was designed in 1873 for use in the Springfield Model 1873, with materials and metallurgy of the era.

The load data may be taking into consideration these older rifles.

The .450 Marlin is designed to be a higher pressure cartridge than the .45-70, so the reverse could mean that a .45-70 is not meant/designed to be high pressure.

SAAMI industry standards may be different for the two cartridges.

 

[BAGTIC]

SAAMI pressure limits


45-70 28,000 psi
450 Marlin 47,862 psi


Nominal net case capacity (H2O)

45-70 59.38 gr.
450 Marlin 55.27 gr.

The modern 45-70 case is designed to withstand the same pressures as any modern 'standard' (non-magnum) rifle. Example 270, 25-06, 308, etc.

The only advantage of the 450 Marlin case is that is will not fit in a 45-70 chamber so there is no risk of some fool loading a modern high pressure smokeless powder load in a gun designed for the old low pressure black powder loads.

 

[American Made]

IIRC, the 450 Marlin case was designed to have thicker brass in the critical head area to help withstand the higher pressure generated by factory loads in that round, and to act as an added safety measure since the chamber walls and barrel shank aren't as thick as on other lever guns of lesser caliber.

 

[fred243]

Won't the belt on the Marlin add some strength to the case ? I bet the 57.1 grs is a compressed load for the Marlin.

 

[American Made]

Won't the belt on the Marlin add some strength to the case ? I bet the 57.1 grs is a compressed load for the Marlin.

It seems like it should, and I read that it is one reason the belt is longer front to rear than other belted rounds. Obviously the belt was mainly added for headspacing.

 

[BAGTIC]

The belt is higher to prevent it from being fired in other belted cartridge chambers.

The belt adds nothing to case strength. The only reason for the belt is to prevent this higher pressure cartridge from being fired in weak guns. Because of its greater capacity the 45-70 will produce equal ballistics at a lower pressure than the 450 Marlin.

 

[BAGTIC]

It seems like it should, and I read that it is one reason the belt is longer front to rear than other belted rounds. Obviously the belt was mainly added for headspacing.

Why? The original 45-70 already had a flange (rim) that provided perfectly adequate headspacing. Think of that rim as a rearward positioned belt. They both fulfill the same function.

 

[American Made]

The belt is higher to prevent it from being fired in other belted cartridge chambers.

The belt adds nothing to case strength. The only reason for the belt is to prevent this higher pressure cartridge from being fired in weak guns. Because of its greater capacity the 45-70 will produce equal ballistics at a lower pressure than the 450 Marlin.

That might have been better if it read- "The belt is higher to prevent it from being fired in other belted cartridge chambers long enough to chamber loaded 450 Marlin rounds" Loaded factory rounds won't come close to fitting std length magnum chambers, and won't even fit in Weatherby chambers based on the std magnum case head for magnum length rounds like the 300 and 340. Not until you get to the 416 Remington will a loaded round chamber. I just checked them all side by side for length. depending on the exact bullet, the 450 Marlin may have chambered in the 416 if the belts were the same. If the round had the same belt and was chambered and fired in a 458 Win or Lott, not much would happen. No, the langer belt wasn't solely to prevent chambering in other magnum chambers.

I agree that the belts on most magnum rounds are there only because the original had one to provide headspace, and for years, a belted magnum would not have sold at all without the belt on it. However, having extra/thicker brass in the head area definitely doesn't hurt anything and may even help a tiny bit with the added length of the 450's belt.

 

[American Made]

Why? The original 45-70 already had a flange (rim) that provided perfectly adequate headspacing. Think of that rim as a rearward positioned belt. They both fulfill the same function.

Because the belt is needed (and was originally designed as part of the round) to prevent the round from being fired in 45/70 chambers only. If they had used the flange for headspacing, obviously some jackwagon somewhere would have loaded a 450 Marlin in his trapdoor and blew the thing up.

 

[MikeG]

And the belt it smaller in diameter on the .450 than the rim on the .45-70. This is not a trivial thing in the Marlin action - it's a squeeze to get the big rimmed .45-70 in there, make it fit the mag tube, carrier, and so on.

 

[rifter]

Why? The original 45-70 already had a flange (rim) that provided perfectly adequate headspacing. Think of that rim as a rearward positioned belt. They both fulfill the same function.

The original .45-70 case was a two piece folded head affair, shortly thereafter changed to what we call a one piece balloon head case today. Modern .45-70 is a solid head design similar to a revolver cartridge case, only bigger.

I'm pretty sure the .450 Marlin is a stronger case with thicker head and side walls, and operates at a higher pressure. That accounts for the increase in velocity.

 

[kdub]

Have to agree with rifter on this.

.450 Marlin has a stronger case than the 45-70 and the added belt is to assure it won't chamber in the 45-70.

 

[baddad457]

I can tell you right now why Marlin and Hornady made that belt longer.............it was to prevent anyone from making 450 Marlin cases from other Belted magnum cases.(like 7mm Rem Mag or 300 Win mag) The only other belted magnum that shares that longer belt is the 378 Weatherby, in which cases are far more expensive to buy. They in effect cornered the market on the 450 Marlin loaded rounds and brass.

 

[Walt45]

I knew a title with "45-70" in it would get peoples attention! Could someone take a caliper and check the case thickness for the record? The reason I ask for the caliper test is how could a .458 bullet fit both cases and not have head space issues? Besides, aren't the 450 Marlin rifles just 45-70 Marlin rifles adapted with proper extractors and barrels with different rifling?



Sorry for all the stupid questions.

 

[Mainspring]

...how could a .458 bullet fit both cases and not have head space issues?

The bullet has nothing to do with headspace.

Besides, aren't the 450 Marlin rifles just 45-70 Marlin rifles adapted with proper extractors and barrels with different rifling?

That might be a simplified explanation, but I'm not sure what you're getting at.

 

[American Made]

Besides, aren't the 450 Marlin rifles just 45-70 Marlin rifles adapted with proper extractors and barrels with different rifling?

Basically, yes. That, and the fact that the Marlin round is entered into SAAMI at much higher pressure than the 45/70. That is why the case was altered to have a belt instead of a rim, and why the brass is thicker in the head region on the 450 case- to keep the hotter Marlin factory load from being fired in the older amd weaker trapdoor springfields, and provide an added measure of safety.

 

[Wrench Man]

I can tell you right now why Marlin and Hornady made that belt longer.............it was to prevent anyone from making 450 Marlin cases from other Belted magnum cases.(like 7mm Rem Mag or 300 Win mag) The only other belted magnum that shares that longer belt is the 378 Weatherby, in which cases are far more expensive to buy. They in effect cornered the market on the 450 Marlin loaded rounds and brass.

The price of the Weatherby brass is irrelevant, the DIA of the rim is larger therefore you couldn't make 450 brass (.532"dia) out of 378 brass (.579"dia) if you wanted to!

If you want a shoulder THUMPER! step up to the plate and do it right!

 

[baddad457]

The price of the Weatherby brass is irrelevant, the DIA of the rim is larger therefore you couldn't make 450 brass (.532"dia) out of 378 brass (.579"dia) if you wanted to!

If you want a shoulder THUMPER! step up to the plate and do it right!

I never said you could. I only pointed out that the Weatherby brass was the only one that shared that longer belt. My 500+ gr 45/70's (I've pushed em up to the mid 1700 range ) will thump your shoulder just as hard as a lighter bullet in the 450. Velocity isn't everything. Or if you really want to get pushed, try my double 45/70, that's 1040 grs of bullet at 1500 fps.

 

[rifter]

You've got to keep this in historical perspective for it to make sense.

The .45-70 was designed in the black powder era at the beginning of the use of brass cartridges. In those days, if you needed more power, you increased the amount of black powder that was burned, which in turn meant a longer, fatter case. That presented mechanical problems when it came to forming the case, which is why the original .45-70 was a two piece folded affair. They weren't very strong and even in the relatively weak Trapdoor action, it was common for the head of the case to tear off when the rifle got hot and dirty.

They figured out how to use the cup and draw method which was much stronger, and that's how we got the balloon head design. That type case was in use until the 1920's in a number of the older calibers. Elmer Keith talked about using that type in his early .44 work.

But it was Peter Paul Mauser who revolutionized cartridge cases when he used a solid head, rimless design for the 7x57 Mauser, necessary to accommodate the pressures of the new smokeless powder. Belted cases came along when Holland & Holland found that headspace was easier to maintain in the long tapered .375 by adding a belt to the case.

So, today's brass utilizes the most modern metallurgy available, and the strongest case designs as a result of over 100 years of trial and error. There have been NO significant improvements in case design (other than better metallurgy) since the advent of the .375 H&H.

The differences between .45-70 and the .450 Marlin are strictly pressure related. The .45-70 being limited due to all the older rifles of sometimes questionable strength still in use. The .450 pressure limit is much higher and is only limited by the strength of the lever action design. The same round in a bolt rifle could handle a fair amount more.

One of the more common custom conversion some years ago was to rebarrel the Siamese Mauser to handle the .45-70, thus enabling much heavier loads to be used. So, it isn't the capacity of either case that is the determing factor, but the strength of the action it is to be used in.