Problems fireforming 300 Wby Ackley Imp.

[chuckgreen]

I recently acquired a really nice 1K heavy gun in 300 Weatherby Ackley Improved. It shoots great with the fired brass I received with the rifle but I'm having trouble fireforming some new Weatherby headstamp .300 magnum brass that was part of the package.

The brass was professionally prepped by Ron Hoehn. Belt removed, primer pocket uniformed and the necks turned to a thickness of .0105. The chamber is a .332 neck.

I tried fireforming some of the new brass with a moderate load of H1000, some 190SMK's and F210M primers. I originally used a .326 bushing and then tried a .322 to size the necks. I was told that until the brass is fireformed the round will headspace on the ogive of the bullet so they should be jammed tightly.

Unfortunately, I don't think I'm getting a tight enough jam as about 40% of the rounds have hits too light to ignite the primers even after several tries. It seems like the neck brass is so thin that even sized with a .322 bushing the bullets aren't being held tightly enough in some cases to headspace properly.

I'd appreciate any thoughts on how I might solve this problem. I know I'm getting some jam because most of the rounds that do not fire will hold the bullet in the throat when I extract the unfired round and on several occasions I've dumped powder in the action trying to get the round out. Not good. I'm wondering what else I can try. Thanks.

Chuck

 

[Cheechako]

Chuck

Those "light hits" mean exactly what you suspect. You are not getting a crush fit from the bullet alone. The energy of the firing pin spring is enough to drive the case forward.

There is also a very good chance that those rounds that do fire may be stretching in the web area. Not good. You might want to section one of the cases you've already formed just to be sure.

Your best alternative is to forget trying to use the bullet as the "crush". Expand the case necks to a larger caliber, say 8mm or even 338 or 358. Then size the neck down to 30 caliber a little at a time until you get a really good crush fit.

That is always the best way to fire-form, IMHO.

Usually, in a situation like this I would say that your chamber is not cut correctly because an "Ackley Improved" chamber should be a crush fit with the standard cartridge and shouldn't need a bullet to hold the case against the bolt face. But since the brass was originally belted it may be that the chamber is OK and the brass simply has the shoulder too far back. Or maybe it's not really an Ackley Improved.

Regardless, you have to live with what you got so go ahead and fire form some cases the right way and you should be OK.

Ray

 

[chuckgreen]

Thanks for the feedback, guys. I'm going to try expanding the necks with a .338 die and then sizing down just far enough on the neck to get a slight crush fit from the expanded neck area. That might do it..