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slimjim Super Member
Joined: May 16, 2009 Posts: 8314 Location: Fort Worth TX
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Posted: Tue Mar 20, 2018 5:37 pm Post subject: Erratic Velocity |
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Elvis turned me on to the a new load for the .270 Win using Hodgdon's Superformance. Superformance is not a standard .270 powder. Hodgdon does not list it in its loading data. I did find load data on BarnesBullets.com using Superformance with 130 and 140 grain bullets. Some reloaders are posting velocities around 3000 fps with 150 grain bullets. This was enough to motivate me to investigate using Superformance with Hornady's new 145 grain ELD-X bullet. The ELD-X with a BC of 0.57 (measured) with the muzzle velocity of a 130 grain bullet would really extend the .270's readn and could be considered a game changer.
I used new Remington and Winchester brass with magnum primers and a 3.370" COAL (mag length but still a ways from the lands. I started 55.5 grains and worked up to 57.4 grains without indications on pressure signs with the primer. Velocity peeked at 3000 fps at 57 grains then fell 100 fps with 57.4 grains - time to stop. However, velocity progression was not consist/linear like I typically find with a powder charge vs velocity ladder.
The only thing I can point a finger at is there was significant case capacity (empty) space in the case. Could this be causing the velocity variation? Is their a filler I can use to maybe improve the situation? I often use tissue stuffed into the case when I do reduced loads to keep the powder stack up against the primer.
Your thoughts and suggestions are appreciated.
_________________ "To anger a conservative, lie to him. To anger a liberal, tell him the truth." - Theodore Roosevelt
"The world is a dangerous place to live; not because of the people who are evil, but because of the people who don't do anything about it." - Albert Einstein |
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slimjim Super Member
Joined: May 16, 2009 Posts: 8314 Location: Fort Worth TX
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Posted: Tue Mar 20, 2018 6:10 pm Post subject: Re: Erratic Velocity |
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Here is a plot of velocities. I typically get a straight line. With good powders, it can be very linear.
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_________________ "To anger a conservative, lie to him. To anger a liberal, tell him the truth." - Theodore Roosevelt
"The world is a dangerous place to live; not because of the people who are evil, but because of the people who don't do anything about it." - Albert Einstein |
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English Mike Super Member
Joined: Jan 08, 2007 Posts: 1709 Location: Whitehaven, Cumbria, UK
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Posted: Tue Mar 20, 2018 7:48 pm Post subject: Re: Erratic Velocity |
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The .270 does seem to perform best with load densities at or near maximum.
I guess you could try a filler but I think there's more to it than that.
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slimjim Super Member
Joined: May 16, 2009 Posts: 8314 Location: Fort Worth TX
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Posted: Tue Mar 20, 2018 8:09 pm Post subject: Re: Erratic Velocity |
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English Mike wrote: |
I guess you could try a filler but I think there's more to it than that. |
I expect you are correct, English Mike. Just searching for any other possibilities.
_________________ "To anger a conservative, lie to him. To anger a liberal, tell him the truth." - Theodore Roosevelt
"The world is a dangerous place to live; not because of the people who are evil, but because of the people who don't do anything about it." - Albert Einstein |
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SingleShotLover Super Member
Joined: Dec 26, 2007 Posts: 1005 Location: Illinois
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Posted: Tue Mar 20, 2018 8:11 pm Post subject: Re: Erratic Velocity |
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Long cases seldom seem to do their best with less than 90% or more load density in my experience. Short (BR type) cases can get away with less sometimes. I always attribute results to uniformity of ignition related to powder position in the case. I generally try to choose a powder for any given cartridge that best fills the case, without compression, and is projected to generate the best velocity. I work up loads by starting well under maximum and work up by degrees (bigger cartridges with slower powders about .5 grains at a time and .2 grains with smaller capacity cartridges and faster powders) and watch groups sizes for the node that gives best accuracy.
_________________ If you can't hit it with one, you probably can't with two either!
The biggest problem with a closed mind is that it never seems to come with a closed mouth.
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Elvis Super Member
Joined: Jul 27, 2008 Posts: 9253 Location: south island New Zealand
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Bushmaster Super Member
Joined: Jun 12, 2005 Posts: 11391 Location: Ava, Missouri
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Posted: Wed Mar 21, 2018 8:21 am Post subject: Re: Erratic Velocity |
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Accuracy?
_________________ I have one nerve left and yer standin' on it...
DEMOCRACY Two wolves and one sheep voting on what to have for lunch...
LIBERTY A well armed sheep contesting the outcome of the vote... |
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inthedark Super Member
Joined: Jan 31, 2011 Posts: 913 Location: Ontario
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Posted: Wed Mar 21, 2018 12:36 pm Post subject: Re: Erratic Velocity |
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I was told one time by a collector of old black powder and smokeless powder rifles that you can use course ground corn meal as filler in a cartridge to keep the burning of the propellant more consistent. The idea being that you filled to case to 100% capacity to keep the propellant close to the primer or initiating element. That's all I (think) I know but I'll leave it to someone who knows more to correct me????
_________________ Chimo
Ron
War is sweet to those who have no experience of it, but the experienced man trembles exceedingly at heart on its approach - Pindar 518-438 BC
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SingleShotLover Super Member
Joined: Dec 26, 2007 Posts: 1005 Location: Illinois
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Posted: Wed Mar 21, 2018 3:16 pm Post subject: Re: Erratic Velocity |
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Problem there is that the corn meal has to be added as additional projectile weight. Might not be much, but has to be considered.
_________________ If you can't hit it with one, you probably can't with two either!
The biggest problem with a closed mind is that it never seems to come with a closed mouth.
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Vince Site Admin
Joined: May 25, 2005 Posts: 15715 Location: Brisbane AUSTRALIA
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slimjim Super Member
Joined: May 16, 2009 Posts: 8314 Location: Fort Worth TX
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Posted: Wed Mar 21, 2018 7:04 pm Post subject: Re: Erratic Velocity |
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Elvis, I should have mentioned I was using a magnum primer.
_________________ "To anger a conservative, lie to him. To anger a liberal, tell him the truth." - Theodore Roosevelt
"The world is a dangerous place to live; not because of the people who are evil, but because of the people who don't do anything about it." - Albert Einstein |
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slimjim Super Member
Joined: May 16, 2009 Posts: 8314 Location: Fort Worth TX
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Posted: Wed Mar 21, 2018 7:10 pm Post subject: Re: Erratic Velocity |
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Bushy, this rifle is a 1/2 moa with IMR4350. I haven't done any fine tuning yet but I'm haven't got below 1 1/2 moa yet.
I'm going to pack the excess space just for curiosity. Give me a week or two.
_________________ "To anger a conservative, lie to him. To anger a liberal, tell him the truth." - Theodore Roosevelt
"The world is a dangerous place to live; not because of the people who are evil, but because of the people who don't do anything about it." - Albert Einstein |
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Bushmaster Super Member
Joined: Jun 12, 2005 Posts: 11391 Location: Ava, Missouri
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Posted: Wed Mar 21, 2018 7:38 pm Post subject: Re: Erratic Velocity |
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I will try to be patient.
_________________ I have one nerve left and yer standin' on it...
DEMOCRACY Two wolves and one sheep voting on what to have for lunch...
LIBERTY A well armed sheep contesting the outcome of the vote... |
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Elvis Super Member
Joined: Jul 27, 2008 Posts: 9253 Location: south island New Zealand
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Posted: Wed Mar 21, 2018 8:55 pm Post subject: Re: Erratic Velocity |
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ok....maybe Im missing something...maybe just dumb.
what kinda plurry graph is that????
I take it the blue dots mean you fired 10 shots????
so why is one stuck out in no mans land under 57???
why is only 56.5 showing 3 dots/shots
take out the 2 lower velocity readings ,one at 56 the other at again no mans land just under 57.5 and then have another look at your line,its pretty darn near straight and velocity spread/variation is pretty darn good....
from the little written about this powder,where it works its awesome where it dont its not flash and will have you pulling out hair.......
if Im reading it right your 56.5grn 3 shots have VS of 25fps or less???? and you pushing a 145grn pill at just under 3000fps...THAT ALONE would be an awesome load WITHOUT any more tweeking and says to me project worth time to continue.......but yeah the blue dot thing has me beat,surely there should be 3 dots per line or an average per 3 shots for each charge weight.
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Aloysius Super Member
Joined: Nov 03, 2009 Posts: 2440 Location: B., Belgium
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Posted: Thu Mar 22, 2018 2:19 am Post subject: Re: Erratic Velocity |
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Just to disturb you a little: I never use a filler (unless you call toilet paper wad in a cal. 12 filler material). With small amounts of powder (as f.e. reduced loads) I point my barrel high, tap slightly my rifle so that all powder is seated near the primer and shoot. (after aiming of course, not just shooting into the sky!)
And I see they recommend the use of magnum primer... I only use magnum primers with powder of a slow burning rate (fe: Vihta's N160, H1000,... ALWAYS magnum primers!). I would not recommend the use of magnum primers in your example. You don't crimp. I expect that the magnum primer already "unseated" the bullet before the powder ignits. This is an uncrontroled action, so you never know how much space is in the case at the moment the powder ignits.
So: try normal primers, no fillers and point your barrel a second to the sky before you shoot. That's far better than adding another variabel thing like a filler.
just my humble opinion.
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