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PaulS Super Member
Joined: Feb 18, 2006 Posts: 4330 Location: South-Eastern Washington - the State
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Posted: Mon Aug 07, 2017 4:09 pm Post subject: Just a quick FYI on 257 Roberts |
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I started working up a load for my 257 today and made a bit of a mistake.
I didn't think it through and loaded standard pressure loads in some +P brass. What I got was the first signs of over pressure. Heavy bolt lift and marked primer flattening. Nothing real severe but when I got back home and compared the +P loads and the regular pressure loads I found out that due to the smaller capacity of the heavier +P brass the loads are actually 3 grains lighter than the standard loads in regular brass. So my starting load of 48 grains of H414 with an 87 grain bullet was already 1 grain above the max load for a +P case.
I am going to have to make up different loads for the two types of cases that I have. I am hoping that I have more standard cases than +P cases.
I don't normally make mistakes like this and it is a good reminder for me to double check the sources when it comes to +P for the 257 Bob. That is what I get for assuming ...
The only cost was the 30 rounds that gave me no usable data and my pride. Onward and upward!
_________________ Paul
__________________
Speer, Lyman, Hodgdon, Sierra, and Hornady = reliable loading data
So and So's pages on the internet = NOT reliable loading data
Always check data against manuals
NEVER exceed maximum listed loads |
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Elvis Super Member
Joined: Jul 27, 2008 Posts: 9253 Location: south island New Zealand
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Posted: Tue Aug 08, 2017 12:05 am Post subject: Re: Just a quick FYI on 257 Roberts |
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you still have your teeth Mate so chalk it up to experience and thank the good Lord you still in one piece.
_________________ You shot it You pluck it !
Them who eats the most duck eats the most feathers! |
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PaulS Super Member
Joined: Feb 18, 2006 Posts: 4330 Location: South-Eastern Washington - the State
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Posted: Tue Aug 08, 2017 4:15 pm Post subject: Re: Just a quick FYI on 257 Roberts |
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Nope! lost most of my teeth years ago - but I was the last in my family to lose them.. some kind of genetic flaw. I should have been born with shark genes.
Yeah, I was lucky this time so I wanted to pass on the notice to others. The +P cartridges are a lot smaller than the standard. I will have to lat the +P cases aside and work up my loads with other cases. Oh darn! I have to load and shoot more ammo. How very disappointing...
Wait! I love it!
See you all later.
_________________ Paul
__________________
Speer, Lyman, Hodgdon, Sierra, and Hornady = reliable loading data
So and So's pages on the internet = NOT reliable loading data
Always check data against manuals
NEVER exceed maximum listed loads |
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slimjim Super Member
Joined: May 16, 2009 Posts: 8314 Location: Fort Worth TX
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Posted: Tue Aug 08, 2017 7:24 pm Post subject: Re: Just a quick FYI on 257 Roberts |
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Glad you didn't run more than some flat primers. I've always found that brass makes a significant difference and I never could develop a load in one manufacturer's brass and assume it would work in another. Though I've never run into a situation with a 3 grain difference like you did here.
_________________ "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: 11393 Location: Ava, Missouri
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Posted: Wed Aug 09, 2017 9:08 am Post subject: Re: Just a quick FYI on 257 Roberts |
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I had to look it up...I'll be damned. Still learning I guess. Never ran across a rifle cartridge that was marked "+P".
_________________ 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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PaulS Super Member
Joined: Feb 18, 2006 Posts: 4330 Location: South-Eastern Washington - the State
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Posted: Thu Aug 10, 2017 3:57 pm Post subject: Re: Just a quick FYI on 257 Roberts |
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So far, I think the 257 Bob is the only one. What I don't understand is why they use a case with less capacity to build the +P loads. Did somebody tell them that the brass was too light to use a 50000 PSI load? Did they forget that the chamber supports the brass and pressures?
I am going to do as much work with the standard brass as I can. As I collect more brass I will be sure it is not the +P brass.
_________________ Paul
__________________
Speer, Lyman, Hodgdon, Sierra, and Hornady = reliable loading data
So and So's pages on the internet = NOT reliable loading data
Always check data against manuals
NEVER exceed maximum listed loads |
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slimjim Super Member
Joined: May 16, 2009 Posts: 8314 Location: Fort Worth TX
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Posted: Thu Aug 10, 2017 5:10 pm Post subject: Re: Just a quick FYI on 257 Roberts |
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The case web, just forward of the extractor groove and case head is not supported by the chamber wall. To beef the case web up, the brass must be thicken with resultant capacity loss. this is the situation with the 6.5 Grendel, it has a 52,000 psi limit because of a thin bolt and case web. 6.8mm SPC II has stronger brass and has a 58,000 psi limit.
_________________ "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: Thu Aug 10, 2017 5:11 pm Post subject: Re: Just a quick FYI on 257 Roberts |
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I measure case web expansion on new brass all the time as one of my indicators of chamber pressure.
_________________ "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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PaulS Super Member
Joined: Feb 18, 2006 Posts: 4330 Location: South-Eastern Washington - the State
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Elvis Super Member
Joined: Jul 27, 2008 Posts: 9253 Location: south island New Zealand
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Posted: Sat Aug 12, 2017 2:19 am Post subject: Re: Just a quick FYI on 257 Roberts |
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so load up the
+p cases with something along the lines of a heavy partition at good speed for accuracy and keep them for your bush /closer range loads
then use all the rest for all the rest with something along the lines of ballistic tips/SSTs so no way you will mix them up.
just a thoguht...
_________________ You shot it You pluck it !
Them who eats the most duck eats the most feathers! |
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slimjim Super Member
Joined: May 16, 2009 Posts: 8314 Location: Fort Worth TX
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Posted: Sat Aug 12, 2017 3:08 am Post subject: Re: Just a quick FYI on 257 Roberts |
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Elvis wrote: |
so load up the +p cases with something along the lines of a heavy partition at good speed for accuracy and keep them for your bush /closer range loads
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Always the practical one that Elvis. Agreed, use the +P brass for one load where you don't need the case capacity then the other brass for another one of your favorite bullets.
_________________ "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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PaulS Super Member
Joined: Feb 18, 2006 Posts: 4330 Location: South-Eastern Washington - the State
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SingleShotLover Super Member
Joined: Dec 26, 2007 Posts: 1005 Location: Illinois
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Posted: Sat Aug 12, 2017 5:04 pm Post subject: Re: Just a quick FYI on 257 Roberts |
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I would be interested in knowing what your velocities were. Maybe the case capacity increases pressure as well as velocity making the lower charge weights acceptable. I notice you are using H414, which according to a Handloader article is the same powder as AA2700 and W760. My lot of AA2700 produces near maximum velocities at nearly 2 grains less than the listed data in my .243 Winchester.
_________________ 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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PaulS Super Member
Joined: Feb 18, 2006 Posts: 4330 Location: South-Eastern Washington - the State
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Posted: Sun Aug 13, 2017 2:27 pm Post subject: Re: Just a quick FYI on 257 Roberts |
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I did know that W760 and H414 are the same powders but I didn't know that AA2700 was part of that club.
_________________ Paul
__________________
Speer, Lyman, Hodgdon, Sierra, and Hornady = reliable loading data
So and So's pages on the internet = NOT reliable loading data
Always check data against manuals
NEVER exceed maximum listed loads |
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SingleShotLover Super Member
Joined: Dec 26, 2007 Posts: 1005 Location: Illinois
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Posted: Sun Aug 13, 2017 5:19 pm Post subject: Re: Just a quick FYI on 257 Roberts |
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Since I have quite a lot of AA2700, I was pretty happy to find that out. Makes load data a little easier to find for some cartridges with normal care in development. The jugs in my lot are at least 17 years old and the formulation at that point is a bit too warm to rely on today's data, but it is still a good place to start.
_________________ 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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