Changing Brand of Brass-how much does this effect a pet load?

[dougduey]

A question for all of you seasoned reloaders out there. I usually use one brand of brass and stick with it once I have a load worked up. Recently, I purchased another brand of brass since I got such a great deal. How much will this effect my pet load and what kind of new load work up do I need to do?
This is for my 6.5-284 Norma. I used Nosler brass, but now I have a bunch of Lapua brass.
My pet load is 57.6gr Retumbo, 210M primer, 143 ELDX. This load is pretty much at max in my rifle with the Nosler brass.

Thanks
Doug

 

[BallisticsGuy]

Keep in mind that my use case is match shooting, not hunting. That said, every time I think, "Naw, this will work out, it's just different brass. The cases even weigh the same and hold the same amount of water. It won't group differently or have a very different muzzle velocity." I find out ever so slightly too late that that was a stupid thing for me to think and I shouldn't have thought it. That's not to say I don't sometimes persist. Hey, I have a Y chromosome. It turns men stupid once in a while. Point of interest: I get different enough results just going from virgin brass to once-fired that I have different loads for those so brand-to-brand, yeah, expect some difference. Testing will tell you how big it'll be. Can't guess or assume. I'd plan on re-developing the load or at least re-tuning it.

 

[Deleted member 46119]

It turns men stupid once in a while.

ROFL

Even same brand, different lots can be very different. I notice this more so in "sorted" premium brass, Lapua, Nosler, Norma all exhibit this.

As @BallisticsGuy points out. Even same brand, same weight can have different reactions.

The standard is to back off and work back up to the accuracy/velocity/barrel timing node. It could be different but not really far off.

 

[Geno1112]

Load several of each brand and take em to the range.
For many hunting applications, the difference will be minimal, if at all.

 

[Mikecr]

Difference is difference regardless of application.
I will never understand the notions that things matter less for hunting.
With hunting you're shooting at a living animal in the field(not a pristine paper target), no bench rest, no sighters/prefoulers/warmups, no wind flags, you get one shot, the ranges are not pre-set, and if long ranges and success is expected from the efforts -everything matters.

I vote that brass brand changes(and possibly lot change of same brand) will affect the tune. Even if all else somehow matched(I doubt it), the composition of brass is likely different, it can expand/spring back differently. This represents a dynamic capacity difference, especially if FL sizing.
If not FL sizing, it's possible the brass will simply fire form to tuned H20 capacity, and you'd be fine there.

 

[Rhovee]

I'll put it this way. I just loaded some rounds up for a buddies 300wm using RL 26 with lapua brass. Ran into pressure at 79 grains. Dropped to 77.5 and tried junky hornady brass and blew the primers out on the first shot. Hornady brass had 3 grains less with water.

 

[Deleted member 46119]

I'll put it this way. I just loaded some rounds up for a buddies 300wm using RL 26 with lapua brass. Ran into pressure at 79 grains. Dropped to 77.5 and tried junky hornady brass and blew the primers out on the first shot. Hornady brass had 3 grains less with water.

@dougduey

So you see, it is best to start over with load development with each brand and maybe even each lot from the same manufacturer.

Norma/Nosler weight sorts their brass but that means one box could be significantly different from another. I have experienced this with Nosler brass for several different applications. RUM, xx-Nosler, 260 Rem. Different boxes were very different H20 capacity after fire forming.

 

[Rhovee]

I was pretty shocked. I took the bolt out and looked at the face. You could read "300 win mag Hornady on it". It was virgin Hornady brass so not shot out. The lapua brass was 2x fired.

 

[Garycrow]

It definitely changes things. How much it will change is an unknown until you actually shoot it. If I were switching brass I would drop back a couple of grains of powder and chronograph it, working up until my velocity in the new brass matched the velocity in the old brass and see how it grouped. The powder charge might or might not be the same.

 

[Frank in the Laurels]

There's no way to tell until you let fly !!

 

[desertbull]

I'll put it this way. I just loaded some rounds up for a buddies 300wm using RL 26 with lapua brass. Ran into pressure at 79 grains. Dropped to 77.5 and tried junky hornady brass and blew the primers out on the first shot. Hornady brass had 3 grains less with water.

Where are you buying Lapua 300WM brass?

They don't list it as one of their offerings on their website.

 

[Rhovee]

They quite making it a long time ago. Found a secret stash.