Old Data and Load Variations. Traps for New Handloaders

Greetings All,
In another thread I talked about my simple methods for validating load data. The cartridge was the .260 Rem with the 140 grain plus projectiles and AR2209 powder. I have started a new thread to stop cluttering up the other and to possibly reach a wider audience.
To me there was a glaring difference between the max loads for the 142 grain Sierra SMK and the Hornady 143 grain ELDX. For the former the quoted max was 44.5 grains of AR2209 for 2735 fps and the later it was 42.9 grains of the same powder for 2,759 fps. To me the projectiles are very similar so loads and velocities should be as well. I have banged on about the speeding up of AR2209 a little after 2,000 so I hunted back through my old load data. The Sierra projectile data goes back to at least late 2,000 and likely to 1997 or 1998 after the .260 came out so this is old data. The 143 grain ELDM did not exist then and did not for some years after so its data is newer.
So why does the ELDM need 1.6 grains of AR2209 less to reach a little more velocity? The speed of AR2209 has definitely changed as I found in a paired chronograph test a few years back. Loads needed to be reduced by1.5 grains to give the my original velocity with the new batch of AR2209. I am not bagging ADI or Hodgdon and definitely not AR2209 which is a great powder in my opinion improved by an increase in speed. Hodgdon does a great job producing and upgrading data tor their and ADI powders but it is still our job as handloaders to spot these little gremlins. My experience is that most powders are pretty uniform but all of them vary over time and from batch to batch. This also applies to other components so how do we keep on top of things?
My system is to chronograph a reference load with new batches of components to detect changes in velocity and pressure. Generally this yields no surprises but sometimes it does and my standard load can be adjusted.
Lets be careful with those loads.
Regards Grandpamac.

Banging on about it. New powder,new rifle,new bullet weight.start low and work up slow.low used to be 10% below maximum.....your 2 grain difference would be more than accounted for if dropped ten percent of a??? 35_40?? Grn load... The more things change,the more the old rules stay the same.

Different length of projectile?

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Originally Posted by STC

Different length of projectile?

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Greetings @STC,
It is not the projectile but is the powder speed increasing. I ran a test a few years back using the three lots of AR2209 in my 6.5x55. The projectile was the 129 rain SST in Lapua cases Fed 210 primers and 45.5 grains of AR2209. Loaded in the same session and fired at the same time. The chronograph was my Oehler 35P using a 4 foot screen spacing. Powder packed 01-2000 produced 2,720 fps and recently purchased powder 2,805 fps. Chronographed results from the older powder and an even earlier batch from my records validated the change in speed was not due to the age of the powder. The velocities from the Hodgdon/ADI on line data match the older lots of powder. I have found other reports of this increase in speed on the internet as well as reports of the 44 grain load for the 142 grain Sierra projectile mentioned in my OP being excessive.
The reference loads mentioned in my OP are generally one or two grains (depending on case capacity) below my developed working loads. It is a quick and easy way to check if new components have effected velocity and hence pressure.
Regards Grandpamac.

I know bullet jacket shape and thickness impact pressure,
ie ELD-X vs ELD-M. the X needs less powder as its thicker jacket creates more pressure as it enters the rifling.
another trap
Sierra 225gr Gameking vs Nosler Accubond 200 gr. The Accubond needs less powder to hit pressure, It is longer impacing case volume and the thicker tougher jacket is harder to start into the rifling. Based on GRT reloading model and my experiance.
Z

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Originally Posted by ZQLewis

I know bullet jacket shape and thickness impact pressure,
ie ELD-X vs ELD-M. the X needs less powder as its thicker jacket creates more pressure as it enters the rifling.
another trap
Sierra 225gr Gameking vs Nosler Accubond 200 gr. The Accubond needs less powder to hit pressure, It is longer impacing case volume and the thicker tougher jacket is harder to start into the rifling. Based on GRT reloading model and my experiance.
Z

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Greetings,
My experience with the Accubonds is the same. A paired load test with the 6.5mm 129 grain Hornady Interlock and the 129 grain Nosler Long Range Accubond delivered 100 fps more velocity for the Accubond with everything else the same. This equates to a lot more pressure as well. Nosler publishes just one set of data for each weight of projectile so I assume that this is for the harder ones.
Regards Grandpamac.

I know of one forum member that blew up a rifle after mistakenly using a barnes or similar projectile for a normal cupro lead one without reducing loads

Greetings @csmiffy,
If that was the one where the shooter was honest enough to post about it I remember it. From memory it was one of the bigger 6.5's. Some of the data for the calibre is all over the map with higher velocities with smaller charges than you would expect from the later stuff. I work a bit with the 6.5-06 and some of my older data has substantially heavier charges for the same or less velocity. I do wonder if the later US barrels are somewhat tighter than previously. The yanks do have a history of having to re invent things, sometimes with disastrous results.
This is the reason I always work up loads with the chronograph. Higher than expected velocity is almost always in indication of higher pressure.
Regards Grandpamac.

Yes you are correct. A 264 win mag and I have thr barrel for one of my P14 projects

Greetings,
The .264 Win Mag was ahead of its time in 1959 but hampered by the projectiles and powders available at the time. IMR4350 was the slowest cannister powder available with only milsurp powders that were slower but not consistent from lot to lot. This, together with overtight barrels and long bearing surface projectiles made the .264 cranky to load and only 3 years later came the 7mm Rem Mag. Today things are different and I think the .264 was even chambered by Remington recently. Better projectiles and powders have changed everything.
GPM.

Once I have worked up to a load I like and want to keep with whatever batch of powder I've used I try to buy a few containers of the very same batch / lot of the same powder. Saves the reverification hassle arising from buying more of the same powder but being a different production batch / lot. When I have been able to do this it's worked very well for me, so far. Whem I have had to reverify loads due to acquiring a different production batch the only powder that caught me was AR2209 exactly as @grandpamac mentions above. Another I found variation in was IMR4831 although I suspect it was due more to going from quite old to fresher powder as I seldom use it.
The only powder I recall showing nil variation, or at least very little, over many years was AR2213, both the original production in tin cans right up to today's "sc" variant in plastic bottles.