Here is a posting from the Weatherby website I thought you all might find interesting:

The last series of reloading posts showed the effects of changing temperatures on pressure and velocities. But what happens when you change the other components of a reloaded cartridge? Primers, bullets, or brass. For these purposes we will look at one cartridge (308 Win), with just one load (Xgr IMR4895) and change all the other components. Got it?

Bullet-------------Case----Primer------Velocity--------Pressure (CUP)
168 SierraMK----LC------WLR---------2626-----------52200
168 Speer--------LC------WLR---------2625-----------51200
168 Hornady-----LC------WLR---------2625-----------51200
168 Nosler-------LC-------WLR--------2624-----------52100

All bullets are match type. Brass is Lake City Match. Velocities are quite uniform, and all things considered the pressures are rather uniform. In this particular case, changing bullet brands doesn't seem to make a lot of difference. That isn't always the case. Remember to work back up every time you change bullets or bullet lots if you are working on the edge. Actual working pressures (CUP) for the 7.62Nato is accepted as 50000. Commercial 308 Win loads have a maximum average working pressure of 52000 CUP. Generally the piezo-electric method is used now. 52000CUP is equal to 60000psi in the 308 Win using the piezo method. The pressure gun had a NATO spec chamber in a 308 barrel. This post is not about differences between 7.62 NATO and 308 Win specs, so enough said about that. If you happen to have a European match rifle in 7.62 NATO, be aware that most continental barrels are tight. Many of them are running only a 305 barrel. Next let's change the primers.

Bullet------------Case-----Primer----------Velocity-------Pressure (CUP)
168 MK----------LC-------WLR------------2626----------52200
168 MK----------LC-------Fed 210M------2622----------51000
168 MK----------LC-------Rem 9 1/2------2571----------45500
168 MK----------LC-------CCI 200---------2581---------45500
168 MK----------LC-------CCI 250---------2579---------46100

Not so much difference in velocities. There is more difference with a primer change in velocities than changing bullets made. The big difference is in pressures. Almost 7000CUP in some cases. Notice there wasn't a big difference in pressures by using the CCI 250 (Magnum) primer in this case. Might not be the case with other components or cartridges. The only changes with table 2 was primers. All bullets were Sierra Match King, etc. Are we all on the same page? Now let's change the brass around.

Bullet--------Case----------Primer--------Velocity------Pressure (CUP)
168 MK------LC------------WLR----------2626----------52200
168 MK------FC------------WLR----------2586----------44700
168 MK------WW-----------WLR----------2580----------45300
168 MK------RP------------WLR----------2589----------46400

For reloaders who like to think of the brass case as just a little brass bottle that isn't very important, think again. A couple of years ago I wrote a post about brass and checked out the differences in case capacity and weight. In that post, I mentioned that benchresters often measure their powder charges and only weighed their cases. I caught a lot of grief over that statement, even though it is true. Bear in mind that the Lake City brass is heavier with a smaller internal capacity. Different lots of the same brand brass also varies. The different commercial brass results were fairly close. Depends on whether you want fairly close or not.
Originally I had written down the single load used with all this data, but on second thought decided to call it load X. It was less than a max load according to my old Sierra manual. Listing powder charges still makes me uneasy.

now that is food for thought for a sloppy loader like myself. just as well Im well below listed maximums. when I used to chase velocity I would sort brass so Im not completely dence now I just stick to a nice mildish load.

Interesting, I use the brass and primer that resulted in the lowest pressure. Better watch what I change because the only way is up.

That brass has different powder capacities is one point, the other is its relative softness and thickness. I would be interested in knowing if the brass used was new or once fired in the test or another rifle, neck or fl sized. Was it all trimmed to the same length? I assume that the O.A.L. of each cartridge was the same.

In my own weight vs capacity measurements I found that heavier did not always necessarily mean less capacity although this was the general rule.

Well now,
That result of yours is pretty much the same as what I am getting Marty!

When all things are the same,
using Magnum primers somewhat lower the muzzle velocity.

It's also a great lesson to remind us to lower our charges when changing any component and gradually work them back up..

Very Interesting.

It should also be noted that batch to batch differences occur with primers and powders !!!

I don't think it's as much of an issue as it once was but one should still keep it in mind when working with max loads.

SingleShotLover wrote:

It's also a great lesson to remind us to lower our charges when changing any component and gradually work them back up..

Bingo!

Very informative discussions here, I'm hunter too but not a professional and I love to material related to guns and hunting, very helpful threads and posts here, thanks and love to listen more from you more.

Demon00 is getting around again.
I love to material too.

Suzanne wrote:

Demon00 is getting around again. I love to material too.

Ummm not any more he's not


-DallanC

Ah rats!! And I wanted one more swing at him...Darn!!

Good Morning Boss...