How Stupid is this idea for fire forming?

[Troutslayer2]

Reasons I don't think I've got headspace issues.

1. I on my 5th loading with Nosler 280Ai brass, and have only trimmed it once, after the first firing which was with factory Nosler ammo. Other than at that first firing, this brass remains exactly the same size. Wouldn't a headspace issue cause brass growth?

2. I haven't had the problem again, and the stuff that is jammed seems just fine, I am going to shoot it again tomorrow and see if I get separation.

3. The Nosler Reloading Guide #6 says to jam the bullets into the lands when fire forming .280 to .280 Ai to avoid just this problem. I don't think I'm the only one who has dealt with this. Maybe it's that the remington factory stuff is a little on the small side, I mean, we are talking about thousandths of inches here.

I have neck sized only and am now going to go for a 5th firing of the lot of brass, it still chambers fine. If it ever stops chambering I will bump it back.

 

[MrBallistic]

1. I would agree. Typically excessive headspace will cause premature stretching in the web area of the body. But, I have seen plenty of chambers which, after the case is fired, it actually gets shorter when it expands. It's all dependant on the case/chamber/die fit, and of course pressure of the loads.

2. If you suspect separation, I wouldn't recommend firing them. It's really hard on the firearm and always the possibility of a gas finding the shooter. Today's rifles handle pressure excursions very well but just the same, blind shooters are not very popular at my range.

3. The firing pin hits the primer and pushes the case forward until it stops, then continues into the primer until ignition. The pressure spike hits and expands the thin case walls first, essentially gripping the chamber wall. As the pressure wave continues, it pushes the case head back, taking up the space that was created by the firing pin "push".
Seating the bullet out into the rifling is one way to minimize the forward movement of the case. It is also fairly popular with the benchrest scene as some bullet/rifles shoot well with this arrangement. As a previous poster correctly stated, factory ammunition is loaded to achieve the best performance and should not be made to engage the rifling. Use a recommended (read: reduced) load for reloaded ammunition in which the bullet engages rifling.

Factory ammunition will always be undersize as they want to make sure it fits every chamber made and they only intend the case to survive one firing. I have seen factory belted mag ammo near .020" short. It's just flat scary.

Good shooting