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Old August 18, 2012, 05:07 AM   #1
Mac Sidewinder
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Posts: 69
Copper Plated Pressures

I use Berry's Plated bullets and I know they are loaded between lead and jacketed powder wise. My question is: Can I use the speed obtained compared to a jacketed of the same weight and type to estimate how much I should adjust the powder charge? For example:

Berry 124gr HBRN (TP) 9mm
Bullseye 3.8gr
OAL - 1.150
950fps (measured on my chrono)

Compared to Speer manual #14
124gr Jacketed 9mm
Bullseye 3.9gr
OAL - 1.120
966fps

Will these two loads have close to the same pressure developed? Berry's thick plated bullets can be pushed to 1450fps (according to their web site). The Speer manual max load is 4.4gr @ 1059fps. Can I use my chrono and match this speed by upping my charge and still feel safe doing to pressure wise? I know to look for over pressure signs on the fired cases, but I have heard that 9mm pressures spike very rapidly.

The reason behind asking is that I would like to load some test rounds, increasing by .1gr for each set starting at 3.8gr (3.8, 3.9, 4.0, etc) and clock them with my chrono and see which sets I get better groups with. I just want to make sure that I stay on the safe side of the pressure scale.

So back to my original question: Is is safe to use the speed as an indication of pressure when comparing thick plated to jacketed loads?

Mac
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Old August 18, 2012, 07:27 AM   #2
joshf128
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Personally, I wouldn't push too close to the FMJ max powder charge with the plated bullets. I would stick within the lead guidelines. Someone posted pictures of the thickness difference between the plated and FMJ and it was shocking how thin the plating is. They might look like jacketed, but they are much closer to lead.

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Old August 18, 2012, 07:40 AM   #3
Nathan
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In my opinion, for 2 loads of the same powder, same weight bullet, that should be close.

Although, they say lead and plated are the better data match.

IMO, what you show is probably slightly lower pressure in the plated round.

I think Accurate has some data for all 3 which you could study and draw your own conclusions.

Of course, look for pressure signs on the chrono, target, cases and primers. As charges increase, 90% of my calibers start pretty accurate, then about mid range accuracy goes south. Then at max and/or slightly over max accuracy and good chrono numbers return. Slightly hotter than that, groups open up, guns jam and the chrono numbers get bigger for SD. . .oh yea and primers look smacked with a textured hammer.

This all happens before case splitting, gun blowing up or shooting the rifling out of your barrel!

That said, know your powder. If you are shooting a super fast powder, don't mess with max/over max loads. Sometimes .1 gr will cause HUGE spikes in pressure.
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Old August 18, 2012, 09:29 AM   #4
Brian Pfleuger
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It takes less pressure to engrave a plated bullet into the rifling than it does a jacketed bullet. According to QuickLoad, about 1,500psi less. Lower starting pressure means lower peak pressure, about 3,000psi lower using 124gr bullets and Power Pistol in 9mm.

So, working your load up to the max listed in official data is entirely safe.

HOWEVER, "velocity chasing" is not safe. You can't just assume that because the book got 966fps you can too, so you just keep increasing the charge until you get there. Obviously these loads are no where near max, but you get the idea.

In your specific example, I wouldn't see the slightest problem with adding 0.1gr more powder.

Using Ranier bullets at 1.120, QuickLoad thinks 3.8gr Bullseye would give you 959fps at 18,902psi while 3.9gr would give you 980fps at 19,919psi. Obviously far below both max speed for the bullets and max pressure for 9mm.
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Old August 18, 2012, 10:57 AM   #5
dunerjeff
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I've shot thousands of Berrys and quite a few Rainier bullets. I use jacketed data and except for the lighter bullets, I go up to 90% full load(many have been 100%). As long as the velocities are under 1200ish I don't worry about the plating comeing apart. You do have to use common sense on working up the load and watching for any sort of hint of issues as the charge goes up of course.I also watch my paper targets for extra holes that would be a sign of the plating seperating,over-crimping is the most detrimental to the plating than velocity.
Acually in .357Sig, some of mine are getting up in the 1300-1350fps area with no "issues", so they are plenty safe at the 1000fps that you are looking at.
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Old August 18, 2012, 04:40 PM   #6
Mac Sidewinder
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The biggest reason I was asking was that it's hard to find any load data on copper plated. Berry's new 124gr HBRNTP (hollow base round nose thick plated) bullets can (according to their website) be pushed to 1450fps now instead of only 1200. I wasn't trying to get them this fast, I only wanted to increase powder and see if my groups tighten by comparing the speed increase to plated data.

I wasn't planning on going over max plated data but was wondering since these bullets supposedly have a thicker plating if I could approach max jacketed data safely.

I bought the new Lee load manual and it has copper plated load data but now in bullseye powder. But it is refreshing to see someone try to include plated bullets in their load manuals.

Mac
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