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May 22, 2017, 07:48 PM | #1 |
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Go Figure! (45ACP Plated Bullets)
So, yesterday, I researched this forum for information on plated 45ACP round nose bullets. I found more information than I needed but what I did learn is to load either as a lead bullet or on the low end of the jacketed bullets recipes, according to Barry's Bullets.
I looked in my Lee Edition Two and found the following recipes for a 230 grain bullet. Lead bullet - 4.3 grains of HP-38 resulting in 699 feet per second Jacketed bullet - 4.2 grains of HP-38 resulting in 751 feet per second. As Ricky Ricardo said to Lucy, esplain this please. |
May 22, 2017, 07:53 PM | #2 |
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Just an FYI, but this article does a direct comparison of different bullet types loaded with the same amount of powder:
https://books.google.com/books?id=da...cketed&f=false |
May 22, 2017, 09:55 PM | #3 |
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74A95,
I'm sure there is a good explanation. I will read the article from top to bottom. Thanks. |
May 22, 2017, 11:03 PM | #4 |
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Short answer: pressure.
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May 22, 2017, 11:35 PM | #5 |
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Actually doesn't give an explanation but rather presents velocity in chart form for different bullet types or coatings with same powder charge. Includes my favorite, moly coated by Bear Creek. Obviously the different friction coating properties account for the velocity variations with cast lead leading the others in velocity.
Last edited by geosheaks; May 22, 2017 at 11:41 PM. |
May 22, 2017, 11:51 PM | #6 |
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For unknown reason I am signed in above from an earlier registration. Normally I am condor bravo.
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May 23, 2017, 12:40 AM | #7 | |
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Quote:
Assuming, your data is from a 5" barrel, And the intent of the load is full power GI spec. The GI spec for a 230gr bullet was 820fps +/-30fps from a 5" barrel. The listed load doesn't quite make that, its below the low end, in that test barrel. Is that wah you need esplained?? or are you asking why the velocity is different for the same load with different bullets?? The simple answer IS pressure. The slightly more complicated answer involves pressure/time and factors like friction and bore expansion ratio. In simplest terms, the greater the friction of the bullet in the barrel, the higher the pressure needs to be in order to get it moving, and once it gets moving the higher pressure gets it moving a little faster a little sooner so you get a slightly higher velocity reading when it leaves the muzzle. Now, with the data you supplied, we're only talking approx. 50fps, which is not a huge amount. Firing the same load from a different 5" barrel could very well show that amount of difference for either bullet from the figures they got with the test barrel they used. Another barrel might turn in 750fps for the lead and 800fps for the jacketed. Another barrel might show velocities in between or at either end of the range. Its all about how the bullet fits the barrel what it takes to get it started (engaging the rifling) and how "easily" it slides once it does.
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May 23, 2017, 12:54 AM | #8 | |
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This is a quote from Unclenick here at TFL from this thread
https://thefiringline.com/forums/sho...d.php?t=584273 Quote:
http://cakesniffer.org/stuff/boom/RanierData.pdf
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May 23, 2017, 07:35 AM | #9 |
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The short answer
The "data" in the LEE manual is very dated. It is nothing more the data obtained from OTHER sources. They never tested anything. It does not list the "specific" bullet, barrel length or other relevant "stuff" The long answer is posted above. As always YMMV!
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May 23, 2017, 07:54 AM | #10 | |
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Quote:
One thing that puzzles me is why (example) a 120gr plated bullet may show 4.3gr of a certain type powder. Then, same bullet, different weight 125gr shows 4.0gr for same powder. Bullet construction makes sense but same bullet higher weight using less powder leaves me fuzzy... Thoughts?
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May 23, 2017, 08:45 AM | #11 |
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Another thing to consider is that all load data testing from one lab to another will little different results.
Barrels vary, lot numbers, sources, components, equipment, even to the point that decades may pass between one round of testing and another. Where some labs may keep every variable identical, others may change lots and sources of brass to widen the actual test data that they get. Last but not least of all, even the guy who runs the machine, and the dies that he uses can have a small effect. At the very smallest level, how many digits does the lab use? .04 and .0455 (.05) are significantly different. From time to time, there will be some curious anomalies. I'd like to point out that variations in data are not an indication of stupidity or sloppy work on the part of any one lab or testing session. Each lab has huge variations in how the data is gathered, the materials tested, and different protocols. Then, it is absolutely the option of each lab to decide how to interpret and report it. Expect variations.
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May 23, 2017, 05:59 PM | #12 | |
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Quote:
A heavier bullet can't grow fatter so it must get longer. A longer bullet takes up more space in the case. With more space occupied by the bullet the available room for powder is less. |
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May 23, 2017, 07:05 PM | #13 | |
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Quote:
The issue is when bullet get heavier they generally move slower down the bore under same pressures . Also as they get longer they create more friction in the bore do to more baring surface . Those two things mean you can't put as much of the same powder behind because the bullet can't get out of the way fast enough for the expanding gases . You generally need to go to a slower burning powder as you go up in bullet weight . All that is generally speaking when talking heavy for caliber bullets . There are always exceptions . Yes a bullet being seated deeper can raise pressure . I however believe the extra mass and friction created by that extra mass has more to do with the different powder charges .
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May 24, 2017, 10:47 AM | #14 | |
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Quote:
Thanks again!
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May 24, 2017, 03:08 PM | #15 |
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Slower powders ignite less easily, burn less easily, and also require more pressure and heat to properly sustain efficient combustion. Slower powders need larger charges to do the same thin as quicker ones. They function better with longer barrels that allow the charge a longer period of time to fully burnt. They function best with heavier bullets that allow pressure to build,pressure and heat that are essential for the powder to ignite and efficiently burn.
Fast and slow are simple ways of cataloguing them, but if he truth is told, this is really a complex set of properties and variables that are really hard to predict. This is one of the reasons why data can sometimes seem completely arbitrary, and why you MUST approach maximum loads with a little caution. Throwing changes into a carefully balanced process changes it. Changing bullet weight, seating depth,brass weighting number of things will upset that balance and can cause failures, including destruction of the gun and personal injury.
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