Gunsmithing Indicating Rods, Ranging Rods and Grizzly Rods

[Wheres-Waldo]

Coaxial indicate the barrel off the bore, then you will face the rear breech, then turn your major thread diameter, thread relief & thread.

 

[Killswitch Engage]

I indicate with rods and then lightly cut breech face or muzzle to get fresh material. I then indicate again and take another light pass to confirm. Works great for me

 

[300sniper]

Hopefully the finished chamber to bore alignment doesn't change with a 10 degree temperature swing.....


From this morning:

Checking the finished chamber runout (part 1) - YouTube

Checking the finished chamber runout (part 2) - YouTube

Checking the finished chamber runout (part 3) - YouTube

Checking the finished chamber runout (part 4) - YouTube

Checking the finished chamber runout (part 6) - YouTube

Checking the finished chamber runout (part 7) - YouTube

Checking the finished chamber runout (part 8) - YouTube

 

[JJones75]

Hopefully the finished chamber to bore alignment doesn't change with a 10 degree temperature swing.....



From this morning:

Checking the finished chamber runout (part 1) - YouTube

Checking the finished chamber runout (part 2) - YouTube

Checking the finished chamber runout (part 3) - YouTube

Checking the finished chamber runout (part 4) - YouTube

Checking the finished chamber runout (part 6) - YouTube

Checking the finished chamber runout (part 7) - YouTube

Checking the finished chamber runout (part 8) - YouTube

Im sure the chamber to bore relation will now change at all. What I ment in my earlier post about the metal moving with temp change was dialing the barrel in then coming back and checking it was that it no longer would be dialed in to the same point as the chuck and bearings will move

 

[300sniper]

Im sure the chamber to bore relation will now change at all. What I ment in my earlier post about the metal moving with temp change was dialing the barrel in then coming back and checking it was that it no longer would be dialed in to the same point as the chuck and bearings will move

I know, I was just being a smart-ass.

I already cleaned up this morning before I thought about boring a hole in some stock. I wanted to check the machine runout at different temperatures by boring a hole this morning and leaving it setup, DTI and all. Then come back at a later time/day/temp and see what I had then. I still really think the TIR is going to be the same, but the DTI may read at a different place on the dial.

Either way, I pre-bore the body immediately after I indicate the throat. Even if I walked away after pre-boring and came back at a time 30 degrees temp difference, my floating reamer holder is going to allow the reamer to follow that pre-bored hole.

 

[Clark]

It's not the dimensions of the bore changing that worry me - it's the "stacking" of every single dimension in the entire setup changing due to a couple degree temp swing in whatever environment happens to occur in one's shop. I doubt very much that it has even a whiff of effect on the real-world accuracy of a firearm, but I also strongly suspect (once again, without actual data to back me up) that all this talk of precision way down in the low tenths range is some combination of placebo and Pygmalion effects.

I've yet to see a good metrology lab that is set up in a drafty polebarn, but then again I'm no expert in these matters. I did spend a small portion of my career working with a gentleman in quality engineering who'd spent some number of years measuring roller bearings for automotive wheel hubs, and from that I got an appreciation for the difficulty of repeatable measurements when the decimal point is way over on the left side. I'm not expecting a inquiry from Timken any time soon, let's just put it that way.

Please understand that I am in no way trying to suggest that we not attempt to achieve the utmost precision when performing barreling work, but rather that we (or at least *I*) should not fool ourselves (myself) into claiming a level of precision that is simply not reproducible under typical gunsmithing conditions.

I have heard the phrase, "Good enough for government work" or "Good enough for rock and roll", but I never hear, "good enough for gunsmithing".

We should.
As a practical joke I like to tell old gunsmiths that they have wasted their whole lives dialing in bores before chambering.
I point out that eccentric ammo may be inserted with random rotational orientation, but eccentric chambers don't change and always fling bullets off center into the same small bug hole on the target.
If a 0.007" eccentric chamber can shoot 0.7 moa in a rifle being build not expected to shoot 2 moa, then how important could dialing in be at the most?

I worked on an amplifier design 10 years ago. There were 55 components with tolerances that could affect gain that should be 100. I put them in a spread sheet and calculated worst case high and worst case low. It could go negative 100 or positive 10,000. Then I got a population of amplifiers and plotted their gains. It was a narrow Gaussian distribution centered on 100. Errors were adding, errors were cancelling, and the adding were winning by a tiny margin.

Monte Carlo integration - Wikipedia, the free encyclopedia

 

[Straight Shooter]

Good enough for gunsmithing. How soon we forget. I have read it here by more than a few of the most respected smiths here. I can't go a day without getting a gut ache from the butchers on the different forums and people seeing shiney metal and drooling all over it. Horrible chattered and torn up machining. More than a couple fairly new guys dialing in with $20 Harbor Freight indicators that don't even have the capability to measure a tenth little lone hold the tolerance. They are clamping barrels in 3 jaws and bending the hell out of barrels and don't have a clue. We got guys using hand held taps and for truing actions and crowning barrels with form tools in drills and people are sucking it up. "Good enough for gunsmithing." I hear it all the time from one of the most well known smiths. He is a household name in the gunsmith world. His line is, "We're not building diesel injectors here." The older smiths are some of the worst for saying, Good enough for gunsmithing. Check out the preferred smiths on Accurate Shooter. Some of those old guys are advertising chambering between centers and over steady rests. Some are drilling receivers with drills for 8-40 screws rather than milling the holes to correct their locations. Some barrel makers fitting there own barrels are also guilty. They either dial in both ends at the same time or more recently stabbing it in a collet and pushing the button on the cnc. No consideration of fitting the tenon in any way. They just cut to factory specs and state it plenty good enough for what we are doing. Another procedure that nuts me up is fully truing up an action and then lapping the lugs with the trigger in place. Then to top it of, more often than not, the stuff shoots incredible. Guys have been winning matches and been setting records with their rifles for years. Even the newbies running .005" runout seem to get pretty good groups. Maybe it really is good enough for gunsmithing. One thing for sure is you will never hear me say it.

 

[Clark]

Tonight I am converting this barrel that Krieger already chambered to 300WM from Rem700 to Mosin Nagant.
I dialed it in concentric and parallel to the spindle without a gimble.
The spider made with wimpy little set through 6 jaw flex a couple thou.
I love cutting corners

 

[rasta]

centricator

Hi Brian;
I have a similar indicator (Hauser) that I bought in Ebay some years ago ,but i have the manual missing .
if you were so kind as to scan your manual and send it to me by email , it will be very much appreciated
of course all cost will be refunded,
thanks again
mariano
[email protected]

As others have said earlier in the thread - my preference is to indicate internally off of the rifleing (over a good span @ the throat & Chamber) rather than dialing off a protruding rod.

Here is an extra long contact point I've turned up for my Centricator (wtf is that? old school Deckel device for centreing/indicating).
A few have been advocating the use of long reach "Interapid" DTI's for this purpose, but when I looked into acquiring one of these I simply couldn't justify that kind of expense at this time. Then I remembered that I had this gadget and went about investigating how it could be adapted for the purpose.
Spherical contact point is 3.00mm dia.
I tapered it to be quite slender for access purposes inside of .300" mainly and I'd imagine it should have no problems even down as small as .220" (we shall see).
There's been no perceivable deflection under reasonable indicating operating/indicating load so all good in that regard.

The Centricator for Lathe use is mounted either in the tailstock or in the MT tool holder of the Dixon QC tool post