Excessive Runout on New Barrel When Chambering

[markwalker]

Received a new barrel to be chambered up for a long range benchrest project (6 brai)..

My process is to cut off 1/2” from the breach end using a band saw.

Next the barrel was installed in my lathe. Using both a cat head on the out board end and a bision 4 jaw set through chuck.

The first step is to zero out the Bison 4 jaw set through chuck.

Next the barrel is rough dialed in using using a 6” long range rod with a tight bushing at the chamber end... I usually get real close.

Last, I use a .0001” test indicator to verify the barrel is dialed in to .0001” at two places in the chamber end. The test indicator has a 2.5” long stylus.

My problem is the resulting amount of runout at muzzle. I have chambered many barrels and have not seen it this bad before.

I thought their might be something wrong with the lapping process at the breach end, I removed the barrel and cut 2” off and reset the barrel up in the lathe with the same results.

Do I return it to the manufacturer.

Tried to contact the manufacturer (phone/email).. no response,

 

[SBLH10]

Received a new barrel to be chambered up for a long range benchrest project (6 brai)..

My process is to cut off 1/2” from the breach end using a band saw.

Next the barrel was installed in my lathe. Using both a cat head on the out board end and a bision 4 jaw set through chuck.

The first step is to zero out the Bison 4 jaw set through chuck.

Next the barrel is rough dialed in using using a 6” long range rod with a tight bushing at the chamber end... I usually get real close.

Last, I use a .0001” test indicator to verify the barrel is dialed in to .0001” at two places in the chamber end. The test indicator has a 2.5” long stylus.

My problem is the resulting amount of runout at muzzle. I have chambered many barrels and have not seen it this bad before.

I thought their might be something wrong with the lapping process at the breach end, I removed the barrel and cut 2” off and reset the barrel up in the lathe with the same results.

Do I return it to the manufacturer.

Tried to contact the manufacturer (phone/email).. no response,

I have seen as much as .032 ths. run out at the muzzel end when chambering 6PPC match barrels using the same setup as you. And never see any different on the paper. I always do the muzzel end the same way indicating the muzzel end at two points, (two inches or a little more back from crown then at the very crown, then cutting the crown sqaure to the bore.
Chet

 

[DR_2297]

Are you clamping the barrel OD along the length of the Bison’s jaws or do you have something around the barrel so it can pivot as you adjust the outboard spider?

realize that very small movements at the chuck over two short distances (say 2 - 2.5”) translate to large movements at the muzzle 24 - 30 inches away.

 

[DaveTooley]

I don't know of a .0001" indicator with a long stem. Did you add a long stem to a tenth indicator?

 

[markwalker]

Thanks for the input;

The barrel is dialed in only at the breach end... one test point in the throat and one near the chamber end.. about 2” between (in addition to the 6” long range rod).

The bison jaws are very short but I also use a copper ring.

The test indicator is an mitutoyo 513-403 with a 2” stylus.. So yes, the test indicator will measure 0001” but with the long stylus it’s more but I’m only looking for little movement in the needle.

Maybe this is a case where the muzzle and breach end dial in method should be used... verses just the breach end.

The current excessive runout may not fit the barrel channel well (only cleared for HV contour)..

Could time the barrel for 12:00 position but I share that barrel between two different rifles.

I’m trying to upload a video of the barrel setup spinning in the lathe.

I’ve chambered some crooked ppc barrels that shot well.. this one has a lot of runout.

Thanks

 

[Tim Singleton]

No matter what. It’s in your mind at this point.
you’ll be looking for it to bugger

may as well send it back
you’ve done enough to be a good judge that it is excessive

 

[gme]

I stopped using the range rod method years ago, I indicate the muzzle and the throat to zero then drill and bore the chamber so it's running zero as well, then ream, no worries about where the muzzle is pointed

 

[DaveTooley]

I've seen some whoop tee dooos in the first inch or so in a few barrels but never 4 1/2" in. I have to ask could something have crept in affecting your setup?

 

[Alex Wheeler]

How much is it running out? I have had some run out quite a bit, and I have seen ZERO correlation to accuracy. And I track any extremes (good or bad) I come across to learn if they do effect accuracy.

 

[markwalker]

Great responses;

Setup barrel again got the same result,,, but measured the runout at the muzzle.. inserted range rod and measured with a dial indicator for a quick reading.

Here’s the reading..

.035” total

Looks bad, but from the above responses, guess I’ll chamber and shoot it..

Just not used to seeing that much wobble at the muzzle end.

I dial everything from the breach end and let the muzzle go where it wants. Would the other method of indicating in the barrel (two points; breach and muzzle end) work better for barrels with lots of runout...??

My bision set through chuck does not have a lot of adjustment, probably go to a 4-jaw standard chuck.

 

[markwalker]

Here’s the video, sorry I do not have the gages on.. runout at the breach is about .0001-0002” and the muzzle about .03”

Again thanks for your help..

 

[butchlambert]

I chamber the same way as Gary Eliseo and don't have a problem.

 

[clowdis]

I'd ditch the 6" rod. I used this setup for a while and in my mind I knew that barrels were not as bad as what I was seeing for runnout on the muzzle end. Barrels just aren't that bad! I indicate the bore on both ends and have never looked back.

 

[tobnpr]

I dial everything from the breach end and let the muzzle go where it wants.

What I do.
Many pick the muzzle and the throat.
I'd probably give that a try just for the hell of it, but I'd have to weld or bolt on some sort of way to hold the indicator at the outboard spider. Nothing that high up and rigid on my machine.

Would the other method of indicating in the barrel (two points; breach and muzzle end) work better for barrels with lots of runout...??

Here's what's indisputable.
No matter what you do, and how you do it- when it comes to barrels it cannot be precisely replicated.
Ever.
The fact we all do acknowledge, is every barrel is different.
Even the same barrel, set back and re-chambered in a different method, is, well- shorter. It's not the same barrel. Harmonics have changed.

If you change more than a single variable in any study, it's worthless.

Sure, a lot of guys have "evidence" based on their own experiences and that guides how/why they do what they do. But at the end of the day, it's all anecdotal.

Experiment, try different methods, and if you notice a change in results at the target you've got the best answer you can get.

As Alex mentioned, indicators are one thing. The little holes in the target are what really matter.
The rest, is noise.

 

[markwalker]

Tobnpr

Thanks for the words, very kind..I really like your response.

I’ve perfected my method of chambering and it shows up on the target... teen aggs, small groups., ect.

But, I will try the other methods recommended above.. my ability to try it and see what happens on the target is to my advantage and may improve my technique.

As to the given barrel, will chamber it and see what the target says.

Thanks again

 

[spitfire_er]

I did a 6br barrel that had about 25 thou runout and it's one of my best shooters. Just chambered another one last night had 14 thou runout. I'm not worried about it. I just make sure to time them up or down, but usually up.

 

[Judd]

Great info, thanks for sharing!

We need to create an anonymous poll to see how many folks indicate all at one end versus both ends, it would be interesting to see those numbers.

I know some who do both and I know at least one who it’ll depend on how much time he has, the both ends method is faster because you don’t need to “time” the action to the barrel high/low.

 

[jackieschmidt]

I know several shooters who indicate the same way, and yes the barrels run out on the muzzle end.
The only thing it seems to affect is a significant Point of Impact change when switching barrels.
Keep in mind, barrels have various spots throughout the ID that exhibit runout in a random spots.
your barrel happens to have one pretty close to the chamber end.
I do not indicate barrels in this manner.

 

[SBLH10]

I started to reply but just decided not too.

Chet

 

[butchlambert]

Great info, thanks for sharing!

We need to create an anonymous poll to see how many folks indicate all at one end versus both ends, it would be interesting to see those numbers.

I know some who do both and I know at least one who it’ll depend on how much time he has, the both ends method is faster because you don’t need to “time” the action to the barrel high/low.

Why? It will only show what some folks here are doing. It will not show what the majority of the winning smiths are doing.