How NOT to validate your chambering job

[Ksracer]

I wonder why they don't just put those .00005 divisions on the dial of that 2.75" stem indicator to begin with?

Sure would save a lot of squinting. Probably some guessing and speculation also....

 

[LVLAaron]

I'm bad at mathology so I'm sure there's a more complicated explanation, but the grizzly rods have less apparent accuracy because the further away from the bushing you indicate, the less reading you'll get.

If the bushing moves 10 thou, the rod moves zero at the chuck holding the rod.

 

[xr650rRider]

I wonder why they don't just put those .00005 divisions on the dial of that 2.75" stem indicator to begin with?

Sure would save a lot of squinting. Probably some guessing and speculation also....

100 thousandths divisions would be a solid black line

 

[INTJ]

@tobnpr 's point is, the clearance in the grizzly rod (rod to bushing, bushing to lands) isn't a the problem. Your indicator has a LOT of clearance to the bore.. but it's touching and giving you a reading.

I don't disagree that a good indicator is better than a grizzly if you can use one.

But that is incorrect. We can't use a Grizzly rod unless there is enough clearance between the rod and the bushing to allow it to spin. This is true even if we have the rod weighted. If there was truly no clearance as claimed, the chuck would not spin freely when we try to turn it. The bushing would bind on the rod.

But again, for the third time, satisfactory results can be obtained with the Grizzly Rod. My last two 1000 yd BR Heavy Gun barrels have both shot screamer groups and been very competitive, and I used a Grizzly Rod on those barrels. Although, I wonder how much better they'd be if I had used the Interapid? Maybe I'd better rechamber them for next season.....

My Interapid is very lightly loaded--I preload it one turn of the needle, which is magnitudes less than a weighted Grizzly Rod.

But again, what overrides all this theory is actual results. My results have been that the Interapid finds runout when the Grizzly says there is none. If it doesn't work that way for you or anyone else it's no matter to me..........though you and @tobnpr will have to always acknowledge that my way of dialing in is just a little bit better than yours........

 

[LVLAaron]

It doesn't matter if the grizzly rod has 1 tenth clearance or 1 thou. It's just a mechanism riding on the bottom of "the barrel" - just like a dial test indicator.

 

[DaveTooley]

Yep. That is what I expect and I am happy with .0002" when I have to use the 5.5" stem.

The Grizzly rod undoubtably has more error, even with it weighted. It likely takes what, .0002" clearance for the bushing to turn around the rod? .003"? Not to mention the rod flexing.

More importantly, every time I checked my Grizzly Rod dial in with the Interapid, I found the Grizzly Rod wasn't showing all the movement.

But guys need to do it the way they want. We get away with a lot in this game..........

If you think you're getting +/- .0002" @ 5.5" I think you're fooling yourself. There is nothing 5.5" up in the barrel I'm interested.

 

[INTJ]

If you think you're getting +/- .0002" @ 5.5" I think you're fooling yourself. There is nothing 5.5" up in the barrel I'm interested.

There is at 3" though on a 33XC, and the 2.75" tip won't reach.

And that is the conundrum. Use the more accurate tip which doesn't tell you anything about the throat--the part we all say is the most important; or use the less accurate tip but have it on the throat..........

Regardless, I think a 5.5" Interapid is still better than a Grizzly Rod. I know the 2.75" is better......

 

[xr650rRider]

From Fred Zeglin & Gordy Gritters book "Chambering Rifles for Accuracy"

 

[LVLAaron]

I trust a naked grizzly rod more than I trust that indicator with a 2.75" stylus.

Also, Gordy doesn't talk about or use a little weight on the rod to take up slack. It does make a difference.

 

[V35]

I trust a naked grizzly rod more than I trust that indicator with a 2.75" stylus.

Also, Gordy doesn't talk about or use a little weight on the rod to take up slack. It does make a difference.

It does at times. I chambered a 6GT yesterday and used a Gordy rod to rough in. This particular rod always needs a weight no matter if i have 22 or 6mm bushings on it. I had it as close as i could get it, and reached in with the DTI and had to dial out .0006”. My other rods seem to do better, the last 300 PRC i did was spot on 0” with the rod no weight, and ,0001” with the DTI

 

[BuffaloBill]

As others have mentioned in the past, a bushing bears against the lands. So when checking with an indicator stylus, comparing results against a rod & bushing, you’d want to check at the lands, not the grooves to make the best comparison. Correct?

When I’ve checked with the 513-504 in this manner, after dialing with the weighted rod & bushing, the largest difference I observed was maybe 2 tenths. Now my sample size is small, having done only 3 barrels using this method.

 

[Hal]

From Fred Zeglin & Gordy Gritters book "Chambering Rifles for Accuracy"
View attachment 1393741

From Fred Zeglin & Gordy Gritters book "Chambering Rifles for Accuracy"
View attachment 1393741Xr

How did you like that book? Do you recommend in getting it?

Hal

 

[xr650rRider]

How did you like that book? Do you recommend in getting it?

Hal

I think it was worthwhile. They document 2 procedures for chambering methods. Fred for hunting. Gordy for precision. While I don't follow his process exactly, it's a good reference.

Reading about different methods and you can make your own decisions about what is best. Arguing about grizzly rod vs. direct reading DTI. I think there was a discussion about 10-11 years ago on "where snipers hide out" on grizzly rods. Pretty sure it was Chad Dixon with Long Rifles Inc, who said, if your spending all that time indicating but then your using a floating reamer holder and not pre-boring with a single point cutting tool, then you probably just wasted your time. His recommendation was direct indicate the throat, pre-bore, chamber and get on with your life. Then it got into threading at 1000 rpm on manual lathe toward the chuck and I lost interest.

 

[LVLAaron]

How did you like that book? Do you recommend in getting it?

Hal

It’s a good read.

 

[GenePoole]

I think Chad is correct that we waste a lot of time on this. Most of the methods we are familiar with work or they'd very quickly be abandoned. I sure wish someone (not me) would come up with some type of scientific test for this, but alas, I have yet to see an experiment where any of this shows a difference at the target. Just anecdotes (and I'm guilty of that too in another thread).

 

[xr650rRider]

I have 2 Kelbly Stolle Pandas and had 2 Kreiger barrels chambered at same time in 6BR. Poured chamber cast (before cheap borescope) and 1 had a horrible throat. 1 side, lands all the way back to case neck, otherside totally gone. Other barrel had a good looking chamber. They both shot equally well. I did buy a lathe after that.

 

[Ksracer]

How did you like that book? Do you recommend in getting it?

Hal

There is some good info in it for people learning, but nothing revolutionary compared to what's being discussed on the forum. It did reinforce a few theories that I had developed earlier.

I'd sell my copy if anybody is interested in purchasing one.

 

[INTJ]

I trust a naked grizzly rod more than I trust that indicator with a 2.75" stylus.

Also, Gordy doesn't talk about or use a little weight on the rod to take up slack. It does make a difference.

You might have an argument when talking about the 5.5" stylus. But the 2.75" on the Interapid is much more precise than any convoluted configuration of Grizzly rod and weights from what I have seen. More important that what I have seen is what @Alex Wheeler has seen. He uses the Interapid, and no one builds more accurate rifles than Alex. Though many build rifles that are as accurate.

FWIW, I didn't see much difference whether the Grizzly Rod was weighted or not. That's probably because they tend to have a little tension/load on them even when unweighted. I still think they have closer to .004" of accuracy than .002".

I am honestly not sure about the 5.5" stylus. I guess I need to check a 5.5 vs a 2.75 vs a Mit tenths indicator.............like I'll ever have enough down time in the shop to do that..........

But like @GenePoole said, I do think a lot of our opinions here are full of sound and fury but signify nothing. But the sound and fury sure are fun and enlightening.........

I have been sticking to dialing in the bore and breech because it makes the most sense to me to get that part of the barrel straight, and chamber without preboring because that gives most support to the reamer. However........

It would be way faster to stick the muzzle in a bushing in the headstock, dial in just the throat, then drill and prebore. And I am not sure rifles chambered this way would shoot any worse than how I do it now. In theory the chamber would be just as straight, and it would save having to index the barrel. Not that I will chamber any of my BR rifles that way.........

 

[Alex Wheeler]

I was summoned on a good night. Chambered my last barrel, showered, and answered emails and messages. Now Im done for the day. First, I have not shown anyone how I chamber a barrel. Not for any reason, Just no one stood and watched other than friends. Second, trying to convince people of theories on the internet is a waste of time. Prove it with results. Theres a very good reason I do not get into these discussions. I just dont care what anyone else does. If you want to know what you can or cant do, dial in a crown and check it with your .0001 indicator. I know what I can do, you should too. And if you feel the need to convince others I would say you should be more confident in yourself.
If you want my opinion, you all are missing the mark.

 

[INTJ]

I was summoned on a good night. Chambered my last barrel, showered, and answered emails and messages. Now Im done for the day. First, I have not shown anyone how I chamber a barrel. Not for any reason, Just no one stood and watched other than friends. Second, trying to convince people of theories on the internet is a waste of time. Prove it. Prove it. Results. Theres a very good reason I do not get into these discussions. I just dont care what anyone else does. If you want to know what you can or cant do, dial in a crown and check it with your .0001 indicator. I know what I can do, you should too. And if you feel the need to convince others I would say you should be more confident in yourself.
If you want my opinion, you all are missing the mark.

Alex,

This is a fun and worthwhile discussion for those of us who are still developing our technique. I can see how these discussions aren't much interest to you or other accomplished rifle builders since you have it sorted out. It's the same reason I don't post on aviation forums.

However, on this topic, I find the back and forth of great value. We don't really get good info unless we challenge each other a bit. That said my original intent here was to be a bit humorous about the tape in my chamber.

I wasn't trying to draw you in, but I thought it a courtesy to tag you since I was going to mention you. I was thinking of your description of dialing in on your website when I mentioned you.