I'm going to load 10 rounds with the +/- 1 grain brass and 10 random rounds of the "variable weight" brass. I expect that the spread of the variable weight brass will be greater than the +/- 1 grain due to difference in case capacity and pressure. I've heard stories and read numerous articles about the importance of weighing brass for accuracy but I have never seen anyone actually test the concept. To make it easier to see variation (spread size) I'm going to shoot at 500 yards.
Let me first say, shooting rat guns, and shooting 500 yards is way way out of my area of expertise.
But, loading and pressures fall within some of my area...... I don't think a variable of 3-5 grains in case weight is going to make much of a difference, when considering there are other variables involved too. If one was shooting serious heavy benchrest, maybe... again, out of my area of expertise........... Common shooting, no, you would be hard pressed to see. Pressures, no, not 5 grains difference in brass weight.
But, here is something to ponder, but it deals with far far more differences in weight. Today I had to get a 458 B&M ready for a fellow in Louisiana. Basically just check his rifle to make sure feed/function is good, and load a few rounds and send with the gun. He is a pig shooter, and likes to bust the hell out of them. I am loading a 250 Socom from CEB 77/H-4198. A 458 B&M is a 2.240 inch RUM case. Cut, trim to 2.240 and size to .458 caliber. Rifle is a 18 inch Winchester M70 WSM action.
When the cartridges were first developed in 2005 there was ONLY Remington brass available, so everything was based on that case. Today you can't get any Remington RUM. You have Hornady, Nosler and Norma making RUM Brass today. There is a huge difference in weight and capacity of these different pieces.
Remington RUM weighs in at 240 grains, Nosler/Norma at 260 grains, and Hornady is thinner, lighter at 230 grains. These are big differences. I ended up having to test pressures with these and to make sure all of it worked in the various B&Ms.......
The test work was with 450 Grain CEB Solids 76/TAC.
Remington Brass
2276 fps at 60500 PSI
Norma Brass
2287 fps at 58500 PSI
Nosler Brass
2305 fps at 58800 PSI.
Hornady Brass
2220 fps at 52000 PSI
Weight of the case is basically capacity. The Hornady brass being much lighter, thinner, more capacity, so more internal volume, and less pressure and velocity. The Remington, Nosler, and Norma are all heavier, less internal case capacity, more pressure, more velocity with the same loads. I tested the Hornady brass, it will hold 65000 PSI, but you have to up your powder charge with the Hornady to equal velocity and pressures of
the other brass. Not a big deal, but just a bit aggravating if you are looking for top end performance. I do not do that in most cases, believe me, a 450 CEB Solid at 2220 fps is plenty, and will go from end to end on buffalo
and more than enough for elephant and hippo at any angle. 2275-2300 however does drive deeper, and hits harder........
Today I shot the 250 Socoms, with 77/H-4198. Remington brass was 2940 fps, Hornady brass at 2920 fps and Nosler brass came to 2968 fps. Not really a huge difference and this is big bore as well, so it is not near as finicky as smaller bore cartridges.
Probably not really related to what you are trying to do, but just to point out that while most of the time there are so many other factors involved, that 5 gr difference in case weight would not make a difference to me, not in big bores. But those tiny rat shooters are finicky, so test it and find out for yourself. Forget what the so called "Experts have to say"..... I find they don't know near as much as they think they do, thats why I do it myself and find out the truth..........
BTW, 50 yards is a LONG LONG LONG way for me! HEH.... Hell I can't see anything past 50 yards, so I damn sure can't shoot it further........