5R runout demonstrated

[jackieschmidt]

Tiny land tops to support reamer bushing, can be an issue, 7mm and 30 Caliber, barrel set backs especially. Slop between reamer bushing dia. and lands dia is an issue, control this for great results. A set back on an existing chamber where the original chamber is .005 out, will leade to chatter if you do not cut off enough shank so you can clean up the old chamber with a boring bar prior to reaming.

A taper bore with no reamer pilot will cure all ills in this matter.

Probably why I don’t have problems, although I still use a pilot after I taper bore With the compound.

 

[LVLAaron]

Probably why I don’t have problems, although I still use a pilot after I taper bore With the compound.

Sell me on taper bore vs straight?

 

[jackieschmidt]

Sell me on taper bore vs straight?

The reason I do it does not translate well because I do not chamber my barrels the way the vast majority do.

basically, it allows me to insert the reamer well over 1/2 way into the bore before it starts to cut.

I am a proponent of doing what works best for you with the tools at your disposal, letting the rifles function and target being the final judge.

 

[LVLAaron]

Are you using a pusher?

 

[mikecockcroft]

search for Jackie Schmidt chambering video here or on Bench Rest Central for his technique

 

[ronsatspokane]

I am not a gunsmith but I have chambered several 5R barrels. I have never had an issue. I use indicator rods to setup the barrel in the lathe (as in Gritters method). That way I'm sure I'm going in straight regardless of what kind of drift the hole has. I then run a piloted reamer that I match the pilot to the barrel diameter by feel. It never drifts or chatters. I cut slow and use lots of lube. It seems to me that the only way to get measurable deflection would be if you used a dull reamer.

 

[INTJ]

I am not a gunsmith but I have chambered several 5R barrels. I have never had an issue. I use indicator rods to setup the barrel in the lathe (as in Gritters method). That way I'm sure I'm going in straight regardless of what kind of drift the hole has. I then run a piloted reamer that I match the pilot to the barrel diameter by feel. It never drifts or chatters. I cut slow and use lots of lube. It seems to me that the only way to get measurable deflection would be if you used a dull reamer.

Come by the shop sometime and I'll show you typical 5R deflection. You might even get lucky and catch Bruce or Daryle there--they come by all the time.

 

[ronsatspokane]

You are local these days aren't you? If so I'm in. I'll bring the shop water. Just let me know.

As a side note, I'm about to chamber a 5R. Rechamber it that is. Repurposing a 30 inch 6.5 PRC.

 

[ChristianSilver]

I’m no gunsmith, but do all my own barrel chambering. Just turned out two 5R Bartlein’s for my 6 dasher and several others with no issues.
I do not prebore, use a piloted reamer and take small cuts with light pressure on reamer w/ plenty of VV. Keep things clean and tidy. All my chambering jobs have produced excellent results.
I’ve not seen any issues. Interesting read.

 

[Judd]

Or just don't prebore at all on 5Rs so the the pilot is helping the whole way. If I ream slow I get a little "U" at the beginning of the rifling. If I increase the speed to 250+ I can usually get rid of the little U. That said, the little U doesn't hurt anything, but it is a sign of a six flute reamer in a five groove bore.

There has been a lot of hype about 5R, yet almost every LR BR competition barrel out there is 4 groove......

I wondered what caused the ”u” on some barrels…that would make sense. Weird thing is the two I’ve seen didn’t have any noticeable runout. The last one I saw it on was a Benchmark 3 groove 6.5 barrel…those dang odd grooves

Thanks INTJ.

 

[dnellans]

Here's a barrel a someone wanted set back a thread. Ultimately declined to do it and will at some point chop an inch or two off and start clean.

I didn't bother dialing it in any further. I wish I had for the sake of the video but am sharing anyway - Lots of talk about this but I've never seen anyone share any media. So yes, the barrel is not indicated but the "5R death wobble" is pretty clear on the indicator. Feels like about .5-.6 thou (tenths indicator with a long reach tip)

Indicator is at the top of the body just below the shoulder. It was worse on the neck.

I'm a bit confused on how you're concluding that 5R is to blame for this? I see a barrel that isn't dialed in totally , but even at the extremes of that TiR you're seeing something that looks like .0002 movements. I can't even count if there are exactly 5 of them happening on the vid?

Given that only the lands are being cut out, for there to be .0005 movement in the reamer body that far away from the neck would be pretty terrible. I've definitely seen the 5R half moons on a freshly cut barrel, but I've never measured any affect in terms of cutting an octogon even at the neck, let alone down into the body. I wonder if something else wasn't going on with the original gunsmith's setup who did that body.

 

[LVLAaron]

I asked the owner of the barrel to give it to me when he's completely done with it so I can have it in the shop and dial it closer to better show what's going on.

I'm concluding it... because it's there, and is a known artifact of a 5R barrel? This seems to be one of those incredibly divisive topics. Some guys swear 5R is something you have to treat carefully, some guys say it's never ever a problem and all of their barrels are perfect.

It's my guess that one of those groups is measuring things as they go along, and one isn't. Up to you to decide which is which.

The stylus on that indicator is 2.5x longer than what it is calibrated for, so whatever you're reading, it's 2.5x worse.

 

[FireMedic]

I asked the owner of the barrel to give it to me when he's completely done with it so I can have it in the shop and dial it closer to better show what's going on.

I'm concluding it... because it's there, and is a known artifact of a 5R barrel? This seems to be one of those incredibly divisive topics. Some guys swear 5R is something you have to treat carefully, some guys say it's never ever a problem and all of their barrels are perfect.

It's my guess that one of those groups is measuring things as they go along, and one isn't. Up to you to decide which is which.

The stylus on that indicator is 2.5x longer than what it is calibrated for, so whatever you're reading, it's 2.5x worse.

The stylus on the interapid is 2.75” and it reads in .0005 graduations….I can easily break that down into .0001 or finer with the gap that is between the marks.

If you are preboring to the shoulder, I don’t see how the little bit of reamer deflection in the throat will cause the body to have runout…the throat is the only part cutting the lands and that’s the most flexible part of the reamer….I’m not buying it.

The reamer wants to go to the middle. The only way it doesn’t if we do something to cause not to.

If you are getting runout or out of round chambers, I’m guessing you need to look at your machine and/or setup.

 

[GenePoole]

I asked the owner of the barrel to give it to me when he's completely done with it so I can have it in the shop and dial it closer to better show what's going on.

I'm concluding it... because it's there, and is a known artifact of a 5R barrel? This seems to be one of those incredibly divisive topics. Some guys swear 5R is something you have to treat carefully, some guys say it's never ever a problem and all of their barrels are perfect.

It's my guess that one of those groups is measuring things as they go along, and one isn't. Up to you to decide which is which.

The stylus on that indicator is 2.5x longer than what it is calibrated for, so whatever you're reading, it's 2.5x worse.

What is the DTI actually measuring? Where is the stylus touching the chamber. I assumed the first time I saw this that it was a tenths DTI and that would put the stylus in the area of the case body. This made sense as I've seen egg-shaped chambers from any number of problems with setup (with any land count) but you say it is a 2.5 inch stylus? How did you dial this in in the first place and how can you say it is "dialed-in" if there is that much wobble in the throat? I had assumed you dialed it in in two places in the throat and just beyond and were measuring the runout in the body area.

 

[LVLAaron]

Gene, DTI is on the top of the body. This isn’t my chamber job. I was going to set it back a tiny bit for someone, got this far with it, and decided not to do the job and make it worse. I didn’t need to dial it in any further to see that it’s got 5 sides.

 

[Alex Wheeler]

I wondered what caused the ”u” on some barrels…that would make sense. Weird thing is the two I’ve seen didn’t have any noticeable runout. The last one I saw it on was a Benchmark 3 groove 6.5 barrel…those dang odd grooves

Thanks INTJ.

Theres more than one thing that can cause that

 

[INTJ]

Theres more than one thing that can cause that

More than a six flute reamer cutting a five groove bore? Isn't that the primary cause?

Feeds and speeds can mitigate the issue, and some barrel brands seem more prone than others, but wouldn't all the mitigating factors be moot in a four or six groove bore?

 

[Dusty Stevens]

More than a six flute reamer cutting a five groove bore? Isn't that the primary cause?

Feeds and speeds can mitigate the issue, and some barrel brands seem more prone than others, but wouldn't all the mitigating factors be moot in a four or six groove bore?

Its not the number of flutes its lack of support straight across from another land. Thats the claim to fame of the odd groove barrel anyway. The strange looking leades are from the shape of the lands

 

[INTJ]

Its not the number of flutes its lack of support straight across from another land. Thats the claim to fame of the odd groove barrel anyway. The strange looking leades are from the shape of the lands

Agreed. I was just wondering what else was cause the little "U" other than the reamer/ groove odd/even mismatch.

 

[Alex Wheeler]

More than a six flute reamer cutting a five groove bore? Isn't that the primary cause?

Feeds and speeds can mitigate the issue, and some barrel brands seem more prone than others, but wouldn't all the mitigating factors be moot in a four or six groove bore?

Shape of the groove will dictate how things look in the bore scope. Tool push off is just one reason for a certain pattern.