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Can we trust it???
This is from Joe at Real Guns one that should know?


The Model 1895G Part II - Handloads for the .45-70

But first, the un45-70, the .450 Marlin

I was preparing a list of loads I would work up for the .45-70, and I wanted to get a better feel for the pressure dynamics of both the .45-70 and .450 Marlin, get a better understanding of the relationship between the two cartridges and see how far the new cartridge exceeded the full up loads for the .45-70. I ran across the July 2000 "Shooting Times" .450 Marlin article, so I looked through the data, pulled out all of my manuals, and poked around in the various smokeless powder companies' web sites.

Source Cartridge Bullet Powder Charge MV Barrel
Shooting Times .450 Hornady 350 gr AA2015 58.0 2041 18.5
Hornady .45-70 Hornady 350 gr AA2015 59.4 2000 22.0

Same bullet, less powder, 2.5" shorter barrel, yet, the Shooting Times .450 Marlin load out performed the hottest 5th Edition Hornady Ruger No. 1 .45-70 load. The article rated the .450 load at 40,200 psi, while the Hornady listing for the larger capacity cartridge has the .45-70 load at 50,000 cup. When you run both of these loads through reliable interior ballistics software, both come in below 40,000 psi, within 200 psi of one another. This odd load result could have been an anomaly, but it wasn't. The Shooting Times data also didn't track with the Speer #13 reloading manual.

Source Cartridge Bullet Powder Charge MV Barrel
Shooting Times .450 Speer 400 gr N-133 52.0 1994 18.5
Speer .45-70 Speer 400 gr N-133 59.4 1995 22.0

There were bullets included in the review that won't cycle through an 1895. Even Speer specifically excludes their own 350 grain bullet as excessively long for use in this gun. While the ejection port and bolt travel are long enough to clear almost a 2.900" combination, the feed and ejection mechanisms are not. You can expect feed and eject reliability problems to begin appearing above 2.600" COL. Most reloading manuals peg bullet seating depth to result in a 2.550" COL.

My point is not to critique "Shooting Times", they are obviously a first class publication with a first class staff, and clearly a greater mastery of the English language than I could ever muster. My point is, the industry sometimes becomes a little overzealous in putting their seal of approval on new products, while the new products may not actually have much to offer. As a result, data tables and conclusions be set aside as not being credible, rather than serving as basis for understanding
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Pretty crazy isn't it?It just goes to show sometimes independent test are much better than "Some" Reloading Manuals in actual Pressures and Velocities.

Were on our own with Mr. Common Sense..............................Jayco
 

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Pretty crazy isn't it?It just goes to show sometimes independent test are much better than "Some" Reloading Manuals in actual Pressures and Velocities.
Not crazy at all. It does not go to show that sometimes independent tests are much better than some reloading manuals. Because of the inherent variability involved with firearms and ammunition it only goes to show that different equipment and methodolgies will produce different results.

Just use published loads and accepted reloading practices and don't sweat it.
 

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Jayco -

A couple thoughts:

1) note that you're comparing psi and cup data - in a straight wall case like the 4570 or 450, they're probably close... but not the same.

2) remember that even the oehler system is +/- 5% absolute (or worse) and again that on shot to shot variance (ie, with two shots with equal mv you can still see a 5% difference in observed pressure)

3) I suspect the data you're quoting is also from too small of samples - as has been seen here when people post chrono data from 1 or 3 shot samples they can "see" decreasing velocity with increasing powder loads... if one is going to draw major conclusions, one really needs 15-20 shot samples.

Some data one can get away with a small number of data points

www.gmdr.com/levern/smoothdata.jpg

(a squished screen capture form our range chrono - for strings 32 or 33 one could get away with 3 shot samples and get very close to actual data - data is shot number, left to right, and mv top to bottom - each red dot is one shot)

but some data one needs a larger sample size to say anything meaningful... large expansion ratio straightwall full house loads generally need large sample sets to 'find the data'.

www.gmdr.com/levern/lesssmoothdata.jpg

from strings 9 and 10 one is going to need 20ish shots to really find the real average mv

4) from internal/interior (depending on which continent one was educated) ballistics fundimentals, with the 4570 running 2.1gr more capacity, one would expect the 450 load to be running 500-800 psi hotter than in the 4570 context (refering to aa2015 58.0 and 59.4gr loads).

5) probably less important: but when a reloading manual lists data as ruger #1 safe, it may or may not be safe to assume the max loads are actually at the max allowed pressure - maybe for liability reasons they simply decided to back off and call it quits early.

But otherwise, interesting comments on your and jackfish's part.

do shoot straight,
greg
www.gmdr.com
 
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