Chamber runout?

[JSnover]

Just satisfy my curiosity, I'm not working on anything at the moment.
On another thread, a member wrote that he had been told some runout is normal when reaming a chamber by hand. Zero would be preferable, but with a properly piloted reamer how much runout would a talented 'smith accept?

[M-Tecs]

I like to keep mine to under .0002". That is checked after cutting in a lathe but not removed from the chuck?

[B R Shooter]

M-Tecs is right. When done properly in the lathe, it should be close to no runout, and .0002" aint much!

[JSnover]

0-.0002" from a properly set up lathe sounds reasonable.

[EDG]

When you use a .0005" (half thousandth) dial test indicator and dial the bore into .0000 run out you can rough bore part of the chamber so it has zero runout within the resolution of your indicator. When the chamber is finish reamed it should remain basically zero run out.

[DougGuy]

Considering a solid pilot reamer often has several thousandths of available slop between the pilot and the lands, it's anybody's guess how concentric the chamber would be. You didn't say -how- the chamber was reamed but I know this much about most of the Brownell's reamers, they certainly make sure it won't get hung up in the barrel.

Properly piloted you said. A live pilot that fits really snug would still have several tenths you just can't put one tighter without forcing it and taking a chance on it galling. Best case scenario with a good tight fitting pilot might be .0002" and I don't think you could ask for better by hand reaming. You would be lucky if one out of ten came within .0002" but .0005" should be attainable by ten of ten with a *properly* piloted reamer.

[JSnover]

In the thread that caught my interest, the member was reaming by hand.

[Rifle 57]

Sorry but when I see guys on the internet talking about .0000000000000000 run out when doing barrel chambers I some times have to throw the BULL-S***T flag out. When most of them are using a 2 or 3 thousand dollar 1000 pound Chi-com lathe that in
most cases has .0005 to .0015 run out in the spindle in the first place.Also when they run the chamber reamer in the barrel after they have done all of the other machining on the barrel first by the time they get to chambering the barrel their set up has most likely moved any way. Run out is run out all lathe spindles have some even a well known $30,000 Clausing tool room lathe is only guarantied to turn to within .0002 run out. And yes I have done my fair share of benchrest chambering and I use a pretty good 3300 lbs lathe that is in real good condition and it has between .0002 and .0003 run out in the spindle and I am doing good to keep most chambers under .0005 run out and I chamber the barrel in the first operation before any thing can move and then I run the chamber on a live center for the remanding operations. I am not trying to start a pissin match on this subject but the facts are what I have seen in the last 20 years of doing machine work. So I will say I am sorry in advance.
Loren

[JSnover]

Thanks for the replies. I don't see myself chambering a barrel, though stranger things have happened...

[Andrew Mason]

i have seen barrels chambered with .001" runout chambered on a 3 jaw shoot lights out, and the rifle infact won a local shooting match.

not saying i would do it on purpose myself, i like to get 0.0005 or less.

[EDG]

If you have a $250 high quality dial test indicator and it shows no run out when you check your chamber run out then to the best of your measuring capability you have no run out.

I have 10,000 hours running an engine lathe and I have drilled and reamed far more holes than any gun smith ever reamed chambers. After finishing an engineering degree I worked for 40 years as a manufacturing engineer in machine shops where millions of parts were drilled and reamed and I know quite a bit more about precision than one man shop and home gunsmiths.


Sorry but when I see guys on the internet talking about .0000000000000000 run out when doing barrel chambers I some times have to throw the BULL-S***T flag out. When most of them are using a 2 or 3 thousand dollar 1000 pound Chi-com lathe that in
most cases has .0005 to .0015 run out in the spindle in the first place.Also when they run the chamber reamer in the barrel after they have done all of the other machining on the barrel first by the time they get to chambering the barrel their set up has most likely moved any way. Run out is run out all lathe spindles have some even a well known $30,000 Clausing tool room lathe is only guarantied to turn to within .0002 run out. And yes I have done my fair share of benchrest chambering and I use a pretty good 3300 lbs lathe that is in real good condition and it has between .0002 and .0003 run out in the spindle and I am doing good to keep most chambers under .0005 run out and I chamber the barrel in the first operation before any thing can move and then I run the chamber on a live center for the remanding operations. I am not trying to start a pissin match on this subject but the facts are what I have seen in the last 20 years of doing machine work. So I will say I am sorry in advance.
Loren