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Hi unclenick, in my IMR loading book it lists 48.8 grains of 3031 with a 405 grain bullet @ 1706 FPS and 21,100 cup and lists this as a load for trapdoor rifles. This is the load I was going to try but my leg is in a cast at the moment and can’t get to my loading bench, when I can get to my bench ( looks like cast may come off next week) I’ll throw 48.5 grains of 3031 into an empty 45-70 case and see how much space it really takes up. At least that’s the plan for now.
Thanks for the input
Lyman calls out 18,000 cup as the MAXIMUM CUP for Trapdoor rifles in good condition. Use caution going above this number. Lyman doesn’t list any loads that high in their manual. Please confirm by checking a couple of sources before proceeding.
 

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Discussion Starter · #42 ·
Nsb, thank you for clearing that up for me because I was nervous in using the 3031 but I think my 48.5 grain load will be ok . I remember reading somewhere that the old timers would load their bullets out to the rifling filling the case with black powder. But that won’t really work with smokeless powders and that’s where the use of fillers most likely began.
 

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Discussion Starter · #43 ·
In my 41st edition Lyman reloading manual dated 1957 they list a max of 53 grains of 3031 with a 405 grain bullet. With a note for 1886 Winchester only and in my Lyman handbook of cast bullets from 1958 list 45 grains of 3031 for 410 grain bullet no mention of cup for either
 

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Even condensed down, turns out to be a longer story than expected.


Two 45/70’s, one modern on a re barreled Rolling block (on a smokeless action). Still was only running the roller on black powder loads.

Treated them as if there were separate calibers...except for once.

Published low pressure (trapdoor) loads that I was using as a practice load in the Marlin for years.... thinking might be “universal” plikning/practice loads

First (only) shot in the RB was a squib….. bullet still in the barrel. Removed, was a mass of partly melted/ a bit translucent powder kind of melted up against the bullet base.


My fault...had not took into account the long throat of the RB even though I planned it to have that long throat. Planned it to be loaded “long” with more available volume…..was a mistake to try it with the ammo loaded for the short throat Marlin.

Am guessing the initial smokeless burn was enough to move the bullet forward until rifling resistance, increasing volume faster than thew powder could build pressure.

Was lucky the “fire went out” on that shot.
 

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Discussion Starter · #45 ·
Ribbonstone2 , what powder were you using? I don’t think my Shiloh sharps has a long throat, there was no mention of it when I ordered it back in the 1990’s. And it’s my understanding one of the differences between smokeless and black powder is smokeless burns very fast when ignited.... but black powder explodes when ignited...... as a kid I tried to make a fire cracker with a small, cheap plastic box full with about a tablespoon of smokeless powder with a fuse..... I lit the fuse and it just kinda popped the box open and “sparkled” and left a blob of “something” left.... I tried it again with an empty 3006 case, drilling a small hole for the fuse, dumped powder in the case up to about the shoulder then flattened the neck and folded it over twice (dads idea “boy if you want to make it go bang do it like this!”..... ) that time it had the bang I was looking for then dad said it needed to be compressed to make a bang....
 

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The Shadow (Moderator)
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In my 41st edition Lyman reloading manual dated 1957 they list a max of 53 grains of 3031 with a 405 grain bullet. With a note for 1886 Winchester only and in my Lyman handbook of cast bullets from 1958 list 45 grains of 3031 for 410 grain bullet no mention of cup for either
Few things to remember about that data.

1) None of the powders listed are made by the same manufacturers, same process(facility rebuilds), and without confirming positively, a safe bet it's with different ingredients(due to above mentioned facility rebuilds). Data that old, should be resigned as historical reference/curiosity only.
2) Remember that CUP isn't a measurement in the same sense as PSI is.
PSI is like using a tachometer to know how fast an engine is rotating. Whereas CUP is like listening to the sound of one engine, and comparing the sound to another for an approximation of speed.

Cheers
 

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Discussion Starter · #47 ·
That’s good advice, I just read an article on CUP verse PSI and it seem the way pressure is measured in CUP is by expansion of a copper chamber with a fixed point that will leave a mark on the brass case as it expands, kinda like a hardness dimple but in reverse. And PSI is an electrical measurement.
 

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The Hog Whisperer (Administrator)
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Not quite, CUP is a copper cylinder that gets compressed by chamber pressure (separate from the cartridge case). Then the pressure is 'guessed at' by how much the cylinder is compressed. Basically.
 

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Discussion Starter · #49 ·
Got it Mike, but what I read was when the cartridge was fired it compressed a copper “chamber” exposing a metal “piston” that would then leave a mark on the fired case indicating how far the “chamber” moved. Did I miss understand?
thanks
 

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The Hog Whisperer (Administrator)
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I'm sure there's a 'mark' on the case that was fired, if it doesn't blow out completely, but that isn't what is measured. Cartridge brass too thin, and not calibrated as the copper crushers are.
 

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Apparently, when fired the case will be perforated and the resulting disc is left in the crusher opening. See note 8 under PROCEDURE below.

101844
 

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The Shadow (Moderator)
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Crushers are calibrated by lot, into how "squish resistant" they are. You fire reference ammo, measure the squish, look up the amount in a table considering the correction factor, and assign XX amount of pressure being reported.

But crushers don't respond well, or accurately report, impulses; and the speed at which pressure builds can really fool with them. As does a general range of where the simply don't even generally correlate well to reality anymore.


Cheers
 
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So maybe put another way, copper crushers (CUP) are late 1800's early 1900's tech, piezoelectric (what we call PSI) is about 1960-1970's tech. I'm waiting on the report of using lasers!

There are also large differences due to WHERE & HOW the gas pressure is ported/measured. UNCLENICK has written on this a lot here, IE the confusion about measured/reported pressure in .223 Remington & 5.56 NATO. Even some loading manual writers have made mistakes.
 

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Copper crushers and piezoelectric transducers are both still accepted by SAAMI. I know that the piezoelectric systems are more accurate as long as the testing procedure is used properly and properly calibrated. Like everything else the reality is that they are numbers generated by machines without taking all of the variables into account.
More succinctly they are guidelines that are good guesses to follow. Neither system tells the whole story.
 

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The Hog Whisperer (Administrator)
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What do copper crushers "tell" that transducers can't???? :confused:
 

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The Shadow (Moderator)
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Exactly...

Crushers report an amount the slug was squished. Various amounts were all agreed upon, to represent various amounts of CUP; or Copper Unit of Pressure. At various ranges they can, reasonably correlate to actual units of pressure on PSI. Notice I used the word CAN, and didn't use the word "DO".
Since at least the mid 1950's, as far as the recreational world is concerned, the limitations and at times extreme inaccuracy of crushers; has been well known and discussed in print.

The piezoelectric and strain systems, do report on actual units of pressure in PSI. But not only report an ultimate max number, they actually report out the real pressure curve, in time. So you can very easily see what did and didn't happen, when. That is something no crusher could ever hope to do. I do use one such system, and can actually speak to what the system reports. But we've already danced this dance in the global conspiracy thread...

In the context of this thread, the point is trying not to blow up an old gun. XX CUP isn't "A" pressure, it's a general range. Understanding the differences is important.
EVERYTHING that undergoes system pressure cycles: Boilers, air compressors, firearms.
They all have designed(at least modern iterations) lifecycles AT specific pressures. When you go above the design pressures, you begin an exponential decrease in lifecycle.

Cheers
 

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Hi, I’m going to reload some 45-70 for my sharps and my marlin 45-70 using IMR 3031. My question revolves around using a filler of some sort, my background in reloading stems over 30 years but this is my second attempt at loading the 45-70. First was with black powder which of course filled the case. But now that I have the marlin I want a load that I can shoot in both. I’ve heard the marlin doesn’t like BP
So I like any thoughts and suggestions on loads and using fillers and what filler to use.
thanks
I have an 1886 Lever Gun. I load 13 grains of Trail Boss in my 45-70. I target shoot with that load and get pretty good accuracy. Im using lead RNFP from the Missouri Bullet Company. This load is ok for target but you can work up from there for hunting.
 

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Its amazing what you can penetrate with lighter loads using 405 gr. lead projectiles. The 45-70 doesn't need to be hot rodded to be effective. I use 4198 and there is alot of room in the case, I never have used filler. I plan on using the Hornady cases, (shorter) with the Hornady 325 gr XTP projectiles in my new Henry, and the longer standard cases in my trap door. I have never tried 3031 in this caliber. Good luck in your endeavor! Keep us posted.
 
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