Novice 308 brass questions

[Pester]

I have some 308 FGMM in 168 that I have been shooting and I am interested in reloading. I have been borrowing a friends tools and knowledge as I am getting started and he offered me some 308 brass since he does not shoot it anymore. He has got maybe 200 mixed brass and I am wondering how big a difference the brass makes in shooting.

His all looks to be in good shape and from his bolt gun however I thought I read here (cant find it anymore) a thread that said mixing brass would produce different results with the same powder/primer/bullet.

If it does make a difference is there a difference in Federal brass between the GMM and military brass?

Thanks folks...

 

[scissorhands]

Re: Novice 308 brass questions

I personally don't like to mix brass brands. I dont even like to mix once shot brass with twice shot brass, but thats just me. I try to keep everything as consistant as possible in the reloading process.

 

[JohnSH]

Re: Novice 308 brass questions

It depends on what expectations you have in your reloaded rounds. If all you want to do is reload and shoot, taking brass that's in good shape and then properly preparing them for reloading will do. If your interest is in accuracy, that's a different story.

The reason you read mixing brass produces different results is because it likely will. The reason is mostly due to the capacity of the case. Some brass has thick walls which lowers the case's capacity. Conversely, thin walled brass has greater capacity. This affects the pressure (and pressure curve) of a given charge weight of powder. Wall thickness also affects the tension.

On the subject of tension, mixed lots will cause different amounts of tension -- think of it as the elasticity of the brass neck, and that affects how tightly the brass holds the bullet -- on a given seated bullet. One piece of brass may have a greater amount of tension than another. That causes a different level of gas pressure to dislodge the bullet and that affects accuracy when comparing one piece of brass to another. (This is related to why some reloaders don't like to mix once fired brass with twice fired brass. A component of brass is copper, which is work hardened -- the more you flex it, the harder it gets. The more you resize and fire brass, the more the neck hardens. That affects tension. Tension affects accuracy. Google annealing rifle brass for the attendant religious arguments.)

Then there's primer pockets and primer holes and other things.

All of that matters if you are reloading for accuracy. And even "accuracy" depends on your definition.

The reloading section here is an outstanding resource for learning about reloading. The pinned threads at the top of this section is a great way to get a leg up on reloading for accuracy.

All this is my opinion based on my experience. As they say, your mileage may vary.

 

[280nosler]

Re: Novice 308 brass questions

The difference between military brass (NATO brass) and FGMM is pretty big. The military brass will be heavier, therefore the same load in the 7.62 brass will create more pressure than if shot from the 308 brass, due to less space. I do not mix brass for precision rifle, and only shoot nato brass from my scar 17.

Keep in mind, if it is NATO brass, you will have to swage the primer pocket also.

 

[Pester]

Re: Novice 308 brass questions

Thanks. I have been reading most of the information here and its very helpful.

I still have some loaded fgmm so I will hang on to the brass I have and reload that.

the replies are appreciated.