Virgin brass, or once fired!

[ButterBean]

So, now you have me confused, are you all saying that because the shoulder moves forward on new brass when you fire it, that when you load it again even after shoulder bumping back that you are now shooting closer to the lands??
Clear that up for me would you?
Does that mean when you fire your brass the second time if you started at .015 off the lands you now need to be .020 to maintain accuracy.. ?????

You will need to find your COAL or CBTO with a fired case

 

[7stw]

I do my entire little process with new brass except of course no neck brushing. Mandrel for neck uniformity and flash hole deburring and chamfer (only do once for life of brass) length check.

I know this sounds opposite but I always regard the new brass to not be as accurate and wait till its chamber sized to my rifle from being fired to get into the real accuracy shooting. Not saying which works better for most, just my own experience.........also it could be because this is when I start weight sorting and collet neck sizing as well as the necks getting some carbon in them. The case capacity gets more uniform as well I believe. Or maybe its all in my head

Dave, I too, do the same thing, for the most part, except, for on occasion, assuming the same, that the virgin brass isn't going to shoot as well, I've thrown the load together, just to fire it, and it shoots into a hole.
On my latest rifle, I haven't experienced that yet, but I have had at least two that would do that, to the point that I would load some, with virgin brass, un processed, and it would shoot bugholes. So I would use that stuff for hunting. It all shot good, the virgin shot great.

 

[DJ Fergus]

So, now you have me confused, are you all saying that because the shoulder moves forward on new brass when you fire it, that when you load it again even after shoulder bumping back that you are now shooting closer to the lands??
Clear that up for me would you?
Does that mean when you fire your brass the second time if you started at .015 off the lands you now need to be .020 to maintain accuracy.. ?????

Your head space can and probably will be different from a virgin case to a fully sized case and even different from a neck sized only case. When the firing pin drives the cartridge forward, the case moves a different amount forward depending on how much head space difference you might have. So if the bullet is seated to the same coal, it's actually getting released from the case at different lengths from the lands. All that being said, how much all of that effects the group size of any particular rifle, cartridge load & bullet combo is anyone's guess.

 

[dxlbaile]

Thanks I appreciate you clearing that up..

 

[338 dude]

Your head space can and probably will be different from a virgin case to a fully sized case and even different from a neck sized only case. When the firing pin drives the cartridge forward, the case moves a different amount forward depending on how much head space difference you might have. So if the bullet is seated to the same coal, it's actually getting released from the case at different lengths from the lands. All that being said, how much all of that effects the group size of any particular rifle, cartridge load & bullet combo is anyone's guess.

That's what I've been trying to say all along I guess I'm just not good at making my point

 

[DJ Fergus]

That's what I've been trying to say all along I guess I'm just not good at making my point

Lol. I'm not always good at it either. Sometimes I get lucky.

 

[338 dude]

Lol. I'm not always good at it either. Sometimes I get lucky.

Great explanation this time anyway

 

[dxlbaile]

Bill your explanation was spot on.. It just makes you start to contemplate a lot of things.. I have a 6.5 Gap 4 s that shot lights out with virgin brass and not so much with reloads.. Makes a lot of sense to me now that I think about it. The seating adjustments will need to be done once you have some fired brass I guess. Probably the reason some people get turnkey guns that shoot ok with new ammo and then struggle after the fact to reload and get the rifle to shoot. But like it was mentioned it may not affect some rifles to much at all..

 

[Mikecr]

Yeah the headspace potential with new brass doesn't affect best tested CBTO with my guns. This testing having occurred during fire-forming.
That is, it hasn't mattered so far when I find best CBTO. Whether cases are new, 2nd, or 3rd, or 30th fired. 1500 shots later, best CBTO is right where earliest testing proved it -for me.

Perhaps helpful though: the largest cartridge I shoot is 26wssm, none of my chambers are sloppy, my primers are measured as seated with 2thou of crush, and my chambers are kept clean and free of oil (practically dry).
I could picture a point where things are worse. But things can only be just so worse before primers fail to fire.
After all, it doesn't take much for primers seated off pocket bottoms before FTFs occur.

IMO it wasn't changing seating, or not changing, or anything about seating, that produced the very low ES pictured earlier with new brass[#24 338Edge]. I believe it was new brass expansion capping the pressure peaks to a consistent point, like a heavily diminished return. A very forgiving, but fleeting condition.
It would great if we could re-establish the condition over & over with same cases, but we can't. Well, I don't think we can. I am sure that firing new cases forever changes them, beyond actual recovery.

 

[DJ Fergus]

Bill your explanation was spot on.. It just makes you start to contemplate a lot of things.. I have a 6.5 Gap 4 s that shot lights out with virgin brass and not so much with reloads.. Makes a lot of sense to me now that I think about it. The seating adjustments will need to be done once you have some fired brass I guess. Probably the reason some people get turnkey guns that shoot ok with new ammo and then struggle after the fact to reload and get the rifle to shoot. But like it was mentioned it may not affect some rifles to much at all..

I like to set my headspace on a rifle to where the case is barely loading the bolt handle within it's last couple degrees rotation of being fully closed. Some will argue that is not enough headspace. That's fine, I won't argue back about it. But this gives me minimal change in headspace whether I neck size only or bump the shoulder slightly with a full length die. I'm sure there are drawbacks to this, but for me personally the benefits out weight the drawbacks.

 

[Model12boy]

If you used the base of the case as the datum line and seated the bullet to the same OAL... the jump would be the same regardless of the length of case. Assuming the bearing lengths were within reasonable tolerance of each other.

Exactly!! Glad someone else caught that same thoughts here

 

[Buzzsaw]

again, as in all reloading. There is NO proven info either way.
1. Virgin Brass, you can load straight out of the box with fine accuracy in proven rifles. I will run Virgin through carbide sizer button just to make perfect round but its not necessary. Most QUALITY brass is "ready to load".

2. Once fired will need to be FL sized if needed to chamber easy.

 

[ButterBean]

I like to set my headspace on a rifle to where the case is barely loading the bolt handle within it's last couple degrees rotation of being fully closed. Some will argue that is not enough headspace. That's fine, I won't argue back about it. But this gives me minimal change in headspace whether I neck size only or bump the shoulder slightly with a full length die. I'm sure there are drawbacks to this, but for me personally the benefits out weight the drawbacks.

Don't worry what other people say, If it works for you keep doing it

 

[Rooks]

Once fired brass has always boosted my velocity in multiple rifles by just enough to make a difference. Velocity plateaus in virgin brass for me are usually recreated with .5 to 1 grain less powder in fired brass. Monitoring changes in pressure through reading velocity will help maintain velocity when changing any number of variables. Different lots of brass, lots of powder, ambient temperature, barrel fouling condition, throat erosion, all contribute to changes in pressure/velocity. I find that my rifles shoot best when fed a specific happy meal/meals...