33XC

[sfinn1]

Can some one explain a properly polished chamber in 33XC. We all normally finish a chamber with a moderate grit emery cloth.

The 33XC is based off of a .580″ bolt head. Tubb states that “A fired case will extract with little effort when using a properly-polished chamber with a maximum powder charge after resizing with the Superior Shooting Systems FL sizing die.” Tubb’s 33XC die reaches the case head which is important for accuracy.

 

[Klong]

I have a 37XC and I believe it is not a special polished chamber, but just a chamber with no rough areas in it.

 

[dkhunt14]

I have a 37XC and I believe it is not a special polished chamber, but just a chamber with no rough areas in it.

I don't think any gunsmith polishes a chamber smooth. They use a fine paper and let it slightly rough. The case needs to grip the chamber when it expands to help keep bolt thrust down. Matt

 

[DaveTooley]

Matt

Just my opinion but... chamber finish has nothing to do with bolt thrust. We separate case heads, we get hard bolt lift. All signs of bolt thrust. Pressure is pressure.
I have my doubts about chamber finishes contribution to case lengthening.

 

[rhovee]

Add a little water or lube to your case and fire it and see how much “pressure” shows up. If the case doesn’t have something to grab then I agree with Matt, it’s going to have bolt thrust. Same thing was when firing and AI round with blown out body taper. First firing has to be reduced because case walls have nothing to grab and it will show ejector marks easier. As far as how rough or smooth the chamber is.... that’s up to you.

 

[dkhunt14]

Matt

Just my opinion but... chamber finish has nothing to do with bolt thrust. We separate case heads, we get hard bolt lift. All signs of bolt thrust. Pressure is pressure.
I have my doubts about chamber finishes contribution to case lengthening.

I bet you don't polish them mirror smooth. Matt

 

[DaveTooley]

I bet you don't polish them mirror smooth. Matt

No
Most of the time a quick polish with 240.

 

[D.Stone]

I think it's just marketing jargon.

 

[HPMike800]

I has been my understanding that a "Rough" chamber polish helps the round extract easier.

 

[Dusty Stevens]

I has been my understanding that a "Rough" chamber polish helps the round extract easier.

Less surface area=less friction. Rub glass then rub sandpaper and see which one is sticky. Chamber walls are like engine cyl bores. Neither one should be polished

 

[10at6]

David Tubb has sold a lot of stuff to a lot of shooters over the years...Me included