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.

 

[Cbrown3020]

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.

So I have a Cooper Varmint Extreme built on a 21 action. My loaded rounds with 22 gr Bergers measure .193. Fired rounds measure .198. Hope this is helpful.

Kevin

 

[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 shot the Cooper and the fired brass measures .205, so I am assuming the chamber is .206". Allow .001" for brass spring back, right? Nosler brass has plenty of clearance in this chamber.

In the meantime, I bought some Remington virgin brass and it measures .197-.198, so it would work well in your Mach IV chamber, if you can find any. I have a rifle rebarreled by Douglas in 17 FB and fired brass measures .202, so I am going to use the Remington brass in it.

BTW, I called Cooper of Arkansas and they put me through to Glen's voicemail. I never got a call back. I also had a question a few months ago and Glen never called back. I guess we are wasting our time with them.

 

[swd]

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 M21 in 17 MK4 I bought new back around 2000 or so. It gave me strange fits for while so I called Cooper. When the office gal ordered the reamer the reamer company asked if they wanted a standard or match reamer. She assumed "match" was better so that's what she ordered. Turns out that reamer was a .200" tight neck. As soon as they figured out what they had they reordered a standard neck reamer. They offered to open the neck up for me but I just turn necks for it. So you likely have one of the .200" neck rifles. Would have been nice if they contacted people about it..

 

[59f100292]

I picked up some neck turning gear from KM and just started to dabble a few nights back. What do you guys recommend for chamber clearance in the neck? I set it up to turn out loaded at .196, on the assumption it was a total 5.5 thou clearance, or just under 3 thou per side. (Again assuming it is infact a .2015 chamber). Anyone with experience that can tell me if I should go for more/less clearance? They do chamber now.

 

[swd]

I picked up some neck turning gear from KM and just started to dabble a few nights back. What do you guys recommend for chamber clearance in the neck? I set it up to turn out loaded at .196, on the assumption it was a total 5.5 thou clearance, or just under 3 thou per side. (Again assuming it is infact a .2015 chamber). Anyone with experience that can tell me if I should go for more/less clearance? They do chamber now.

.003"-.004" total is perfect but you really need to know the actual neck diameter.

 

[59f100292]

.003"-.004" total is perfect but you really need to know the actual neck diameter.

yea unfortunately I don't know how to determine that other than casting the chamber or shooting a round and measuring the brass as it comes out.