Cooper 38 17 Fireball question

[244remington]

Does anyone know the outside neck diameter that Cooper used for their 17 Fireball Chambers?

 

[59f100292]

Funny enough I have the exact same question for a cooper 21 in 17 Mach 4. Tried setting up a load tonight with nosler fireball brass, it will chamber sized brass with no bullet, but will not chamber a loaded round. Loaded round measures .202” Marker on the case and bullet shows interference on the neck. What ever reamer they used for the Mach 4, has a neck somewhere just below .202. Interestingly the sized brass after pulling through the expander button has an outer diameter of .202 down towards the shoulder, so the brass must constrict a hair when chambering unloaded brass.

Long story short, and I know this doesn’t answer your question for the fireball, but for the Mach 4 at least it’s somewhere in the .200-.201 I’d guess.

I emailed cooper of Arkansas a few weeks back to see if they had reamer prints for the old cooper of montana barrels, and they do not.

 

[244remington]

Funny enough I have the exact same question for a cooper 21 in 17 Mach 4. Tried setting up a load tonight with nosler fireball brass, it will chamber sized brass with no bullet, but will not chamber a loaded round. Loaded round measures .202” Marker on the case and bullet shows interference on the neck. What ever reamer they used for the Mach 4, has a neck somewhere just below .202. Interestingly the sized brass after pulling through the expander button has an outer diameter of .202 down towards the shoulder, so the brass must constrict a hair when chambering unloaded brass.

Long story short, and I know this doesn’t answer your question for the fireball, but for the Mach 4 at least it’s somewhere in the .200-.201 I’d guess.

I emailed cooper of Arkansas a few weeks back to see if they had reamer prints for the old cooper of montana barrels, and they do not.

I have some Remington and HSM factory loads. The Remington measures .200 and the HSM .202 at the neck. The Remington chambers a little stiffer than the HSM. I guess I will have to shoot it and see how much the expanded neck opens. I will report back when I get a chance to see the results.