Stupid fireforming question

[DTF370]

So I ordered a 338LM Ackley Improved barrel from LRI. I also plan to order custom dies since there are no commercial dies available. When reading about them, of course the manufacturers highly recommended sending fully fireformed cases for the most accurate dimensions.

In my limited experience with fire forming, you need to fire the brass a minimum of two to three times to get a completely fire formed case. So, my question is how would you go about loading your brass for the 2nd or 3rd time without reloading dies? I like the idea of having dies made custom to my chamber, but I don’t know how to fire the case three times without having reloading dies to get to the second and third firing.

I would guarantee that I am not the first person to have this concern, I am just hoping somebody can enlighten me with how to go about it. Thank you in advance for your guidance.

 

[TheOfficeT-Rex]

Neck sizing.

You could also have them pick your die dimensions off of the reamer print.

 

[DTF370]

Neck sizing.

You could also have them pick your die dimensions off of the reamer print.

I was aware they could manufacture based on the reamer print, but they seem to recommend against it. Is it maybe not as big of a deal?

Can a 338LM neck sizer be used in this situation?

 

[Supersubes]

Shoot a small ladder test in one grain increments. Run it into pressure. The upper end will have cases that are blown out where they need to be. Combine that with a reamer print and you’ll be good to go.

 

[TheOfficeT-Rex]

I was aware they could manufacture based on the reamer print, but they seem to recommend against it. Is it maybe not as big of a deal?

Can a 338LM neck sizer be used in this situation?

It's perhaps less precise, depending on how the chamber was cut. I wouldn't worry about it. Or you could do as Supersubes suggests.

Sure, either a standard neck sizer, or I've heard stories of people using a neck bushing and a hammer.

 

[Supersubes]

Depending on your chamber, your fire formed case will probably be to big to fit in a standard die. The shoulder will interfere. I really don’t think you’ll have issues. The 338 lm is a brick shithouse strong case. Work up to it but really give it the boot on top end and you’ll have nicely formed cases.

 

[DTF370]

Thanks guys. I will do as you said and do a ladder as well as see if LRI will give me the reamer print as a backup. I had looked at the COW method, but I don’t like the idea of the head spacing being wrong. Would it be beneficial to shoot a high pressure round, then load it using the COW method to ensure a full fireform? Or am I over thinking this?

 

[TheOfficeT-Rex]

Or am I over thinking this?

Probably. But you're a smidge off the beaten path, with a round that's what, 5$ a pull? I don't blame you for doing research.

I don't like the COW method. 1, because it makes me think of the navy term, and 2. It's inconsistent in blowing out the case.

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[Supersubes]

Redding makes at least one 338 lapua AI FL sizer. Probably not cheap, But you can call them to see how close they match. That would almost certainly allow you to reload them, and you could hock it here later for most of what you paid for it.

What I was suggesting above though was to shoot maybe 8-10 rounds. As you work up the ladder, you can measure the shoulder and base diameters. At some point those dimensions will stabilize, which tells you that they can’t grow anymore. Edit: this will either work or it doesn’t, but no big deal. Find a solution to get the necks sized. A 300 Norma die for example would work to at least partially size the neck. Those are $50 from Hornady.

 

[DTF370]

Probably. But you're a smidge off the beaten path, with a round that's what, 5$ a pull? I don't blame you for doing research.

You are being redirected...

forum.accurateshooter.com

That’s all it is man. Just trying to get me shit squared away before I dive into ELR. There’s no better source than the experienced crew here.