What's a reasonable and safe way to start working up a load?

I've got a .225 Win Post-64 Mod 70, and there's not a whole lot of data available for it.

Here's what I know: the case capacity of my .225 is (said to be) 41 gr. H2O, while that of a .22-250 is 43 gr H2O.

If you express "41" as a percentage of "43", you end up with .95(+), so the .225 has 95% of the case capacity of the .22-250.

Is it reasonable — and more importantly safe — to extrapolate and begin loading it with 95% of the propellant weight of the .22-250, given the same bullet, case make, primer and propellant?

Seems to me it would be just fine (assuming you're not thinking of maximum loads, which I generally stay away from), but if I've gone astray, I'd like to know.

Everyone has an opinion on this one.

That said I've built a number of wildcats that I had to "extrapolate" load data for. I did it exactly like you have suggested. Take a similar case and ratio the load data for volume difference. I would probably measure my actual case volume. Probably not needed but doesn't hurt.

Key start low and work up.

Sounds reasonable; If I really want max velocity, which I don't do any more since I got older, I used to load them up until the primers got loose, and then backed off a bit. Look at Ken Waters' Pet Loads; he has done it all.

quote:

Originally posted by ramrod340:
Everyone has an opinion on this one.

That said I've built a number of wildcats that I had to "extrapolate" load data for. I did it exactly like you have suggested. Take a similar case and ratio the load data for volume difference. I would probably measure my actual case volume. Probably not needed but doesn't hurt.

Key start low and work up.

Good advice roger

LEE does it in their reloading manual.

Take the guess work out of new loads. Buy QuickLoad. Amazing software! I check out different loads and see the projected pressure curve, % of volume, % of powder burned. You can find a safe pressure to start and a max to look for.
Yes, it is expensive, but what a great tool! And the software is updated.
Why guess?

Extrapolate is a word that means danger to me. I have the exact gun and 60/50gr Vmax using published data are what I recommend. Why would you risk a nice model 70 on "guess" loads? Of course I've only been reloading for 50+ years.

quote:

Extrapolate is a word that means danger to me.

It would be great to find the exact case, bullet and powder combination you want to use.

As has been stated even manuals extrapolate. Heck looking at my old Hornady manual they describe how the use one IMR powder to form loads for another. Simply because the energy levels are the same. Every powder and bullet combinations in the manuals aren't always shot.

When you start wildcatting you are on your own. So yes find a case with as close a capacity and operating pressure as you can get a starting point and work up. Same as you do in a manual. Start low and work up. Yes some people stop at the max load of a manual. My guess is the majority don't they work up to their rifle and case limits and back off.

I don't think anyone is saying take a 7-08 load and ratio it up to a 7RUM. Just pulled my Nosler book off the shelf. Looking at the 7-08 and 7X57. The 7x57 capacity is 108% of the 7-08. 140gr bullet 4350 the starting load for the 7x57 is 108% of the 7-08. Ending loads will be different because of allowed pressure.

Yes if you do much off the book loading something like QL is a life saver. Or YEARS ago the old Powley(?) reloading disk. If it isn't available you do the best you can as safe as you can.

My edition 5 Sierra reloading manual lists the 225 Win.
Lists 40+ loads with 6 or 7 different bullet weights.
At a glance it appears that IMR 4064 is the favored powder and loads are about 3 to 5% below that of a 22/250 with the same powder. So yes your 5% reduction should work, but I would not start close to the top if it were me I would
get a Sierra manual it's all in there.

Ahhh...found it...August 2001, #212, Stan Trzoniec.

Factory load 55 gr Win PSP ~3576 fs.

55 Vmax, H4895, 30.4 to 33.4, 3348 - 3690 fs.

55 Nos Sp, IMR 4064, 29.9 to 32.9, 3235 - 3615 fs. BEST group out of a R#1 custom barrel, 30.9 gr, 3357 fs. 0.590"

55 Sierra BT and H380 turned in the second and third best groups at 0.610" and 0.652".

You might check AR load data also. You might also check the latest Nosler, Speer and Sierra data for comparisons to the 22-250...might just open your eyes a bit wider...just saying...data comes in all forms and spreads and isn't locked in stone.

AND THE HITS KEEP COMING...Hornady #1, Hodgdon's #27, Speer #12 and Lyman #48 all have data.

Thanks much to all.

I guess it's time for me to bite the bullet (pun intended) and get QL. I really like the idea of it and I can see it opening new opportunities for me (thanks Paul).

And I'll be checking out the August 2001 Handloader (thanks NONAGONAGIN) and seeing if I can track down some of those manuals (thanks NONAGONAGIN).

Thanks again.

Of course I'm aware of variations in case capacity between brands, but I hadn't put that together with the issue I raised. It's yet another interesting piece of our puzzle. And I'd not have thought of drying off cases between weighing them (nit-picking perhaps, but I'm anal compulsive [or is it anal expulsive?] enough to take a look at it as a variable).

I'm pretty careful about trusting any one source of information (other than my own experience with specific combinations of components in a rifle I know).

So I'll use all the information I've found here, as well as the new tools you-all have suggested, as it was intended to be: as an approach to answering questions, not absolute answers.

As Yogi Berra said: "In theory, theory and practice are the same. In practice, they are not."