204 Reloading Issues

[MN0084]

I am reloading my 204 Ruger Howa 1500.

I have 2 reloads in the picture with 9 cases.

The 3 cases on the left are reloaded as follows
Cases trimmed to 1.848
Federal small primers
28 grains BL-C(2)
39 grain Seirra seated at 2.0695" ogive or .020" off the lands
I got 3589fps, 3627 fps and 3603 fps on these shots

The 3 cases on the right are the same but used 28.5 grains of BL-C(2)
I got 3790 fps, 3661 fps and 3718 fps on these shots

The 3 cases in the middle are Fiocchi 32 grain Vmax factory ammo
I got 3930 fps, 3840 fps and 3894 fps

The other picture shows the Fiocchi primers coming out a little.

My issue is at 28 grains of powder I did not have an issue, but at 28.5 grains the primers started to flatten and the bolt is harder to open. 28 grains is the starting point for this reload. The speeds I was getting was not overally fast. But also the primers on the factory loads were coming out.

Any idea what is going on?

 

[243winxb]

The Giulio Fiocchi, Lecco, Italy brass may have a different volume then Hornady brass?

With harder bolt lift, there should be other signs, not just one.

Velocity at 3774 fps/24" barrel, is whats listed for a Hornadys 40 gr V max bullets maximum @ Hodgdon. So 28.5 gr may be maximum for this brass?

The big jump in average velocity (+117) with only 1/2 gr more powder, is a sign of a maximum load.

Strange that the primers on the factory loads were coming out. I would measure head to datum of the factory ammo and compare to the fired brass. The factory rounds may just be under size and not fully expanding to the chamber on firing?
I have seen brass take 3 firings to expand fully to the chamber in 223.

Different components = Different pressure and velocity.

 

[243winxb]

Pressure and velocity SAAMI standards.

 

[Wilbur]

243winxb gave you the straight skinny for the most part. I'll mention, there's no need to load for speed but rather load for accuracy. You may find that when reloaded the primers stay put...as long as you don't oversize the case. And finally, as 243winxb mentioned, when the bolt lift gets difficult in any way, form or fashion...reduce the powder charge. Competition Benchrest competitors will (or have in the past) shoot a difficult bolt lift if their load is shooting well but nobody likes it!

 

[jackie schmidt]

The main reason a primer will back out is the case is gripping the side of the chamber and not allowing the head of the case to firmly plant its self against the bolt face.

If your "headspace" is a little loose, this can happen.

As was said, check the datum measurement by comparing a fired case to an unfired case.

I bet you will find as much as .010 difference.

 

[tim]

Also, probably in that case BL C is probably going to build pressure before speed. It can do that.
IMHO switch powders, you should be able to easily push those 3750-3800 fps.
In my TAC20 which is pretty much ballistically identical, I can push 40 Vmax to 3915fps with N133 or R10X although I have a 26” bbl.