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Discussion Starter #21
Mike,
I have already measured the volume of more than five of each case. I probably should have kept records but I was so disgusted with the numbers I got that I threw them in two buckets and set them aside. When I get time I will do it over and document it in a spreadsheet. I don't expect it will change any minds but It has me forming my own. It might be good to have the documentation in a sticky here so others won't have to go through it in the future.
I will try to get decent photos of the case heads too - but there is no guarantee for that. Photography is not one of my best skills.

Darkker,
"Signs" aren't reliable or accurate indicators of pressure. No doubt you have signs of brass problems, but the much more reliable indicator of actual pressures; you continue to keep a secret.
7) The entire point isn't belittlement, it's education. Yet you continue to hold on to false beliefs of "Signs" and unchanging components. When shown info or data explaining things don't work that way, you continually ignore them or cherry pick certain things out of context
What, pray tell, is this "more reliable indicator" of pressure?
It isn't velocity because that varies with powder burn rate and since each lot of powder is different you may get over pressure with more or less powder. So if your point is to educate the share what is a more reliable indicator of pressure is.
 

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Shooter Paul-- A reading of the SAAMI manual answers most of the questions, I think. SAAMI says, ammo leaving the factory should match velocities given by SAAMI, but subject to tolerances, barrel lengths and other factors wont be the same as their samples. Plus or minus 90 fps is the SAAMI tolerances for their own sample ammo shot in their own test guns!
SO, chrony factory ammo as a base line and know you're more than safe by SAAMI 'says' standards.

I see, SAAMI says, a 100 grain Roberts is 'supposed' to go 2880. The +P adds a hundred to 2990. In my experience, that's a 'hot' load in most rifles, and too hot in a 22" barrel.
SAAMI shot theirs in a 26 inch barrel, so the handloader trying to match SAAMI specs in his carbine is going to leak primers trying.
Hard bolt lift is a high pressure 'signal' that should not be ignored, no matter the cause. Find it and fix it. If changing brass solves the problem, that's a bonus.
 
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Discussion Starter #23
JBelk,
With all the powders available which one is supposed to give a maximum velocity? What barrel length do they test with and what is the internal size and finish? All of those things can change velocities at least as much as the difference in powders.
A fast burning powder is going to need higher pressure to get the same velocity while a powder that produces moderate pressure over a longer time may give higher velocities with much less pressure.

If that wasn't a fact then we would all be loading Unique in our rifles and expect the same velocity as you get with H4350. Velocity is NEVER an indication of pressure. There are just too many variables.
If that is Darkker's "better indicator" he is less intelligent than I have given him credit for. The other problem is that Remington never loaded to even the pressures of the parent case much less to the levels a modern cartridge can safely use. I won't be exceeding the loads in the book that was copyrighted in 1988 and if I run into signs of over pressure I will back down like I was taught to.
 

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Elk Whisperer (Super Moderator)
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The only manuals from 1988 I refer to are my C6, THM 350-400, FMX transmission manuals, 351W, 351-400M and 460 engine rebuild manuals.

Reloading data changes every minute, so even my Lyman 50th is "out of date" as some of the data is STILL in CUP.

Online data is your best bet and is easily accessible even for me. Even a quick phone call or email to the "supplier" will bet you the most recent data.

As I stated before about my 788 in .223 and using three differeny head stamps of brass where the EXACT SAME POWDER CHARGE is noticeablely different in each case, the accuracy is more than acceptable. Now your situation is likely different, so pick a brand and go with it using new updated data.

Jack, MikeG and Darrker have all given excellent advice. Darrker has run pressure trace tests many times so he does know a bit about pressure.

RJ
 
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I've reloaded the 257R a few thousand times and used all brands of brass and currently form 7x57 which is very stout in comparison to ordinary brass. Because the 257R is loaded well below the pressure of modern calibers in the same actions, there is no need to be concerned about case volumes unless you load outside the "book". The problem arises in that the 257R is an old cartridge with lots of variation even in new rifles.

Reloading die and chamber differences can lead to greater than normal headspace, not dangerous, but it can cause excessive case stretching and short life due to wall thinning. I experienced this on a new rifle and after installing a new barrel due to incompatible headspace gauge dimensions. Also tolerances in the chamber and dies can result in squeezing of fired cases near the head thinning the brass case adding to short life. I have experienced this with premium dies.

Regardless of brass or loads, I have had to scrap out brass after several reloads until I set the barrel back reducing headspace to the minimum, avoiding full length sizing and switching to a Hornady generic 257 neck sizing die with no lower case contact.

The other big problem is a 257R in a short action if you intend to use a magazine. The overall length limitation requires deep seating of bullets which is unnecessary if you load single round or have a long action. The seating depth differences is enough to create pressure issues so it is best to stay within the "book" and work up very slowly checking for all the standard signs of overpressure, incipient case head separation, difficulty in extraction, brass extrusion and primer condition.

I've found it extremely difficult to get sub moa out of the 257R and it has required much experimentation especially with 87 grain bullets. Lots of fun but lots of frustration. Hopefully you will have no problems and have an accurate shooting 257R right off.
 

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There's a tremendous difference between 'load data' and SAAMI expectations. What I gave is what the gun and ammo manufacturers have agreed to produce. Nobody is under any obligation to duplicate what they do and we and they are free to use whatever propellant we think best for our application.

I've found the most likely 'best load' for any caliber is very near 100% case full of a powder that at that level gives the best velocity and accuracy. 4350 is almost the definition of 'best' in that size case with medium weight bullets. Check all the books and all the online resources and 'a case full' (bottom of the bullet) of 4350 comes out top every time an any 7x57-based case. Always work up because guns are different, components may be different and its only smart to give the gun a chance to complain before you work it hard.
Once 'slower than cordite' (3031) powder became available, picking powder by 100% case capacity became possible.

If velocity is your only goal, you have to have pressure measurements to go with it. There is no free lunch and according to Newton, they must be closely correlated. Friction and time in the barrel are the only other variables if the cases are fire-formed first.

FWIW-- Speer #1 (1954) shows the maximum load of 4350 w/100 gr. bullet a whopping 5 grains LESS than current Hodgdon online data. 40 vs 45 grains. Hodgdon says it's still less than 45Kpsi. Ken Waters' Pet Loads says two grains more is 'near max' and 'best load'. 7 grains difference in 'data' for the same caliber and components is more than normal and backwards from the usual.
Assuming physics hasn't changed, loading 'data' sure has.
Start a little low and work up. Your load is yours because it works best for you.
Even Ackley commented on the highly variable velocities claimed for the Roberts. Up ot 400 fps for the same loads!

The great thing about the Roberts is its flexibility. Every powder from 3031 to 4831 can work well. Good to have in times of scarcity. All the 'medium-burn' powders will work. 4895 runs good in a meter and only cost 80fps or so.
 

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The Shadow (Super Mod)
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1) A fast burning powder is going to need higher pressure to get the same velocity while a powder that produces moderate pressure over a longer time may give higher velocities with much less pressure.

2) Velocity is NEVER an indication of pressure. There are just too many variables.

3A) The other problem is that Remington never loaded to even the pressures of the parent case
3B) much less to the levels a modern cartridge can safely use.
1) A faster powder doesn't "need" a higher pressure, it creates a higher pressure over the same time period due to gas production speed.

2) Velocity is ALWAYS an indicator of pressure. Zero pressure = Zero velocity.
It is NOT a precise and reliable reporter of any specific pressure. But it is a reasonable indicator of pressure, when used appropriately in comparison to current data being followed. Note any manual that lists the various charges, they also list corresponding velocities.

3A) Based on which evidence?
3B) Are you loading a modern cartridge?
 

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The Hog Whisperer (Administrator)
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I'm confused as to what the problem actually is. Get a reasonably homogeneous lot of brass, and work up what your gun "likes." Isn't that the way it has always been done? :confused:

My .257 Roberts is happy as heck with 100gr. bullets (mostly old Remington Core-Lokts and sadly-gone Nosler 100gr. Solid Base) at, oh, say 2,800-2,900 fps (tang-safety Ruger 77). And everything I've shot with those bullets, is still dead. What's not to like????? :p

If velocity is in your blood, the .25-06 and .257 Weatherby are out there. The Roberts is classy, and effective, without frying barrels..... perhaps one of our more misunderstood cartridges.
 

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I have a new (old stock) Browning A bolt in 257 Roberts. (actually two, one in youth model and one in full size)
I plan on using the Speer 87 TNTHP bullet though I may work up a load with the 120 SPBT for game.
I have been doing some research on the brass trying to find the best brass to use. I ran into a problem right off the bat.
The only new brass I can find is all +P brass. This brass has thicker base and walls than the original brass. (according to the information on Winchester's +P brass development) The +P cartridge has just over 1% increase in SAAMI pressure limits but has a lower internal volume due to thicker base and walls. (over 4% decrease). I would like to use new brass to work up loads but I would rather use the original brass and not +P. Since the cartridge was originally a 7x57mm case necked down to 25 caliber is there any good reason I shouldn't use it?

An extended question is whether more velocity is achievable with the use of proper slow powders at the lower pressure? As a general rule more powder of a slower burn rate in a case with more volume will give higher velocity.
I am considering H414 or H4895 as they are listed as the powders that have higher velocities with lower pressures. I use H414 in my 3006 with very good results. the case capacity to bore diameter in the Roberts is close to the same as the 3006.

The load work-up will be done in small increments starting at minimum listed loads. The chronograph I use is a LabRadar and I will measure high, low and average velocity with extreme spread and standard deviation for five shot groups of each load. The base to shoulder length will be measured before and after the new brass is fired and the case length will be held at 2.23" with overall length at 2.78". I will watch for any sign of excessive pressure as I go up the ladder. Groups will be recorded for each 5 shot load at 100 yards. I am looking for groups under MOA that are consistent over a wide range of temperatures and conditions. (as I always do)

Any helpful thoughts?
I used a lot of the old 4831 in mine. 4895 is a great powder but not really slow in that size case. All the lode data is either very old or consecutive, I’m not sure why. It can be loaded as hot as the 6mm Rem. It’s great little cartridge.
 

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Discussion Starter #30
As I work the loads up in the new brass I will post my findings.
The loads will be worked up with the PPU 7x57 brass sized in my RCBS 257 Roberts dies, with base to shoulder measurements, and cases trimmed to 2.23". The OAL is matched to the magazine and chamber as limits allow.
The powder being used to begin with will be Hodgdon H414 and the bullets will be Speer TNT HP. CCI 250 or Winchester magnum large rifle primers.
The gun I will be using is my Browning A-bolt with a 22 inch barrel. Velocity and related information will be measured with my LabRadar chronograph. Groups will be shot from 100 yards in five shot strings. My search is for accurate loads.

If I get time I will weigh the case volumes for different brass in grains of water and list the results. It is a process for me because I have to weigh each case, fill it with water and then weigh it again, then do the math and copy the data and load it into the computer. I don't use electronic scales or calipers.

Right now I am dividing my time between replacing freeze plugs in my daily driver and painting the exterior of my home, so this is not going to happen fast.
 
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