Questionable reloading data

[ctrout]

I am trying to identify the source of this data.  It appears to be from a magazine or reloading manual.

[Mikey]

Try Cartridges of the World, 10th or 11th Edition.  Mikey.

[Lone Star]

Neither.  It is from one of the Cartridges of the World editions.  The COTW books are great general references, but the load data they list is from various sources, some of it is not tested at all.  That is the case with the data you show, it was developed on a computer, not a test barrel.  Take it with a grain of salt.


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[ctrout]

Thanks for the info.  Is this generally accepted as a legit source?  The specific thing that I have an issue with is the recommendation in the text that it is ok to exceed the SAAMI pressure in modern rifles because the pressure limit was established based on older rifles with less modern metallurgy.  Also, since the rifle that I am considering will have a brand new barrel (probably a Shaw barrel) would it be safe to use this data and use a starting load of 10% less powder and work up from there?

[SuperstitionCoues]

When in doubt, throw it out.

If you have to question the veracity and legitimacy of the reloading data that you are going to use, then you have already answered your own question.  It is suspect, and you are taking a larger risk than you should in developing loads from this.  Not only the cost of your new equipment is at risk, but so is your safety.

I would look to confirm any data against a known source (i.e. Hornady, Nosler, Speer, Sierra, Lee, etc.).  If you can't come close to the data in question within a reasonable margin of error, then don't use it.  The experimentation could be very costly.

And yes, their recommendation to exceed the SAMMI pressures in modern rifles should raise a red flag.  A VERY BIG red flag.

[beemanbeme]

Regardless of what you hear around the water cooler, exceeding the sammi limits, aka hot rodding, really gains you very little velocity compared to the risk you take. 
I can't quote a source but I have heard from a couple of "places" the ratio is 4 to 1.  For each 4 percent increase in powder you may get a 1 percent gain in velocity.  I don't know how that works out to pressure increase.

[Graybeard]

Regardless of what you hear around the water cooler, exceeding the sammi limits, aka hot rodding, really gains you very little velocity compared to the risk you take. 
I can't quote a source but I have heard from a couple of "places" the ratio is 4 to 1.  For each 4 percent increase in powder you may get a 1 percent gain in velocity.  I don't know how that works out to pressure increase.

Rightly or wrongly I do not know but Barness claims to have "invented" this ratio based on his research of pressure tested load data from manuals. I've not put in as much study on it as him but it does seem to be reasonably valid to me.

[ctrout]

I haven't finished the rifle yet.  In fact, all I have so far is the action (actually a complete rifle in .270 Win that I have been enjoying shooting for the past few weeks since I bought it).  I just found a potentially excellent deal on a barrel, dies, and some bullets in the standard 338-06 so I may be going that route anyway.  I originally didn't think that the improved version would gain me much anyway and with the task of forming brass and the AI's tendancy to have shoulders collapse during bullet seating, I have questioned the true value of the Ackley anyway.

[jhalcott]

http://data.hodgdon.com/cartridge_load.asp
  The Ackley Improvement does not always give you as much improvement as you HOPE for. One of the gun magazines ran an article on this. The author used a barrel and shot it first in .06 then rechambered it to Ackley Improved and compared results in accuracy and velocity. Then chambered that barrel to 300Win and  300 weatherby. Repeating the tests at each stage. The long range results were not that impressive over the original 30-06 data.What is wrong with the 270? Since you enjoy shooting it and will get more recoil from the 338 I think the rebarrel will not be as fun!

[Lloyd Smale]

Some of the ackely improved rounnds seem to benifit alot more then others with the improvement like the 250 savage and the 338/06 and the 35 whelen. One other thing that needs to be kept in mind is the powders available to loaders then werent as extensive as they are now and that has closed the gap on some of the improved rounds and has widened it on others. In my  opinion theres just to many variables to be able to stick a 4 to 1 lable on it. Alot depends on the buring rate of the powder and the barrel lenght your using it in and the weight and design of the bullets

[ctrout]

The reason that I will not leave the Savage as a .270 Win is because that's not why I bought it.  I'm not building it so much to be a fun plinker as I am building it to be a mule deer/elk rifle.  I got it as a package gun complete with the original Simmons scope specifically to build a custom project in .338-06 (possibly AI, maybe not).  I have also given some very minor consideration to doing a .35 Whelen or 8mm-06.  I just picked up the loadbook for the 338-06 and have found enough data to be currently pretty well convinced that this will be a standard 338-06 with a 24 or 25 inch barrel.