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Greydog,

Thank you very much for detail description. Your speed is truly amazing. I would need at least 5-6 times more time to do something like that. On the other hand, I managed to master muzzle crowning with Manson kit to the extend that I can do complete crown on the shortened barrel, cut with the saw, in less than two minutes with use of power driver.

"Leave it along" was certainly not a technical term, so I'm sorry for confusion. I believe we're on the same page here. If you happen to have the set of pins with 0.0001" increments, to fit a pin into the bore, it'll definitely work.

In general, and it's my problem, I'm often a bit skeptical about claims of getting verified accuracy below 0.001" - I've used to calculate and verify all these tolerance chains with consideration to bunch of different factors involved, including even the room temperature, so this past experience of mine gets on the way of happily accepting some related information.

Thanks everybody for a productive dialoque.

Mishka,
I have worked in an A/C controlled room doing jigbore work in the old days. I do have Deltronic pins in sets of 25 for each bore size. They are in .0001 increments.It doesn't matter if you are a hack,because your work will show it.

I am not questioning your accurcy to setting up a barrel in a lathe. but how do you know if the bore is perfectly centered in a barrel? it could be off center in the middle of the barrel and still be centered when it comes out the end. but the bore would have an arc in it and at the end of the barrel come out at a slant, then no matter how you set the barrel at the end the bore would not be square to the end . I hope someone can understand what I am trying to say.

Mishka,
This is why I say I cannot know what the actual runout is. I can only relate measured runout. My instruments are good and I have a lot of experience using them so I think I'm pretty close. I also have a pretty solid idea as to what is required to get precise, certifiable measurements. As a demonstration, I used to have apprentices measure a gauge then measure it again after holding it in their hand for a minute. Or measure again after holding the micrometer in their hand for a minute. The variations one could see on a ten inch gauge were eye opening for them.
Using the pins to dial a bore is probably quicker and easier than dialing on the lands. I have used pins or chamber reamer bushings for this purpose but it's easy enough dialing off the tops of the lands that I usually just do this.
Setting up to crown a new barrel is, of course, even easier since we can dial off the chamber or some unthreaded portion of the tenon at the breech end. It's always necessary to re-dial after the barrel is cut to length since no barrel is perfectly straight. Cut off two inches and it seems like it is common to pick up a thou or so of runout.
Years ago, I did all my crowning in the steady with the steady running on a spider or on the barrel itself if I had turned the barrel between centers. This really worked just fine but I have simply changed techniques over the years.
I certainly don't think there is anything wrong with a piloted tool for crowning and think they do a fine job. I only mentioned the time it takes to crown one by way of explaining why I have never bothered investing in such tooling.
The same thing applies to action truing tooling. I think the action truing kits as provided by Manson or Kiff are great but I think doing it in the lathe with conventional tooling is just as good although it is certainly slower. By the way, I CANNOT true up a receiver and recut the threads in twenty minutes!
I have worked with and watched guys who were truly FAST. The strange thing is, the really fast guys didn't look like they were working at it. In fact, one guy always looked like he was just kind of drifting through the day but man, he got a lot of work done! At the end of the day, I would be covered with dirt, grime, and sweat and this guy would be clean and fresh as when he started yet he would regularily bill at least an hour more than I each day. On top of that his bench top was almost surgically clean while mine often looked like one of those tornado aftermath pictures. I hated that guy! GD

Hubert,
I understand exactly what you are trying to say and the answer is simply this; at some point one has to accept that things are what they are. A slight curvature will produce an error at the face which is so miniscule as to be meaningless. One can use a longer pin and dial in two places if he wants to strive for perfection at the face of the crown but it's unlikely this is going to pay off for him when he gets to the next match. In truth, I have always said that if I have a select match barrel and it is that crooked, I'll send it back to the maker rather than try to make a silk purse from the sow's ear. If it is not a select match barrel and I'm not building a benchrest rifle, it's not that critical. GD

Because the length of the bullet is so much smaller then the length of the barrel, it will likely not be a factor. What you really want is to have "clean" bullet release from the muzzle, when any surface of the bullet "breaks" contact with any surface of the barrel at the same time. This is possible only if the crown (which is actually an edge of the bore itself at the muzzle) is both square and concentric to the part of bore (not even the whole length of the bore) near the muzzle. Sighting devices can always be adjusted to compensate for whatever barrel wall thickness deviation we may see between the chamber and the muzzle end of the barrel. As far as I know, bullet is actually guided by the last couple of inches of the bore near the muzzle, that's why even barrels bent at 90 degree in the middle can shoot.

Greydog,

Thanks a lot. I treasure your input. I'm 55, but still learning from other people's experiences. Helps in my business a lot, and good for improvement on the personal level as well...

Hubert,
You can only measure so far into the bore. If you think a barrel has a bore that is in an arc or curve, you are wrong. The way they are machined, they can be in any shape. Most are in a spiral, if anything. A lot of this barrel magic has been posted on the internet and if they are in terrible shape, they are sent back.
All that being said, I have been involved in chambering barrels with very ugly wandering bores as an experiment. They can shoot just as well as a so called straight barrel.
Through the years I have seen many barrels chambered by the internet. If you chamber a few, you will understand.

I don't see how a piloted cutter can be more accurate than a barrel centered in a lathe with a 4 jaw using a 10th's indicator. I haven't used a manson cutter but have used the brownells 11deg cutter before I had a lathe with a large enough headstock to fit a barrel in.

My experience has been I've yet to see the brownells piloted cutter cut a crown that was as accurate as a crown cut on a lathe with the bore zeroed to my ability with a 10th's indicator.

What you've used - Brownells cutting setup - has a rotating pilot, which rotates inside the bore, which also means that there must be a clearance between the pilot and the bore. This clearance allows cutter to shift relative to the centerline of the bore, resulting in loss of accuracy. Manson pilot is of expandable type, does not rotate inside the bore and there is no clearance between the pilot and the bore. This greatly improves accuracy by itself. In addition, Manson cutter uses special serrated carbide blades with multiple overlapping cutting edges of shallow depth, which reduces the value of cutting forces. Smaller cutting forces mean smaller deflections. Cutter driving arrangement is also different, greatly reducing the chance of generating unwanted side forces. Quality/accuracy of Manson tooling is also much higher. This combination of features built into Manson muzzle crowning system makes it a very different tool and produces better accuracy with little chance of chattering. Chatter may be an issue with conventional 11 degree cutter from Brownells.

Are you sure about that "10th's indicator"?? The one I use reads to .0001... If you're using one in tenths, you're not even CLOSE to being dialed in..

And the Brownell's cutter will, if the bore's dialed in to +/- .0005, AND rigidly held in the tailstock, can cut an 11-degree crown with no chatter just as well as a single-point tool..

The critical thing in this whole scenario is bore alignment..


The last barrel I installed from (named manufacturer) had the bore in the muzzle off-center by nearly .017" !!!!

Speed comes with experience and some of these guys are dam good. I wouldn't question anything Butch Lambert has to say about barrel work on the lathe

??? I didn't say a thing about Butch...

I was just speaking in general not referring to anything you posted RN

Sounds like you are confused on the difference between ten and a tenth. Ten thousandths is 0.010", a tenth of a thousandth is 0.0001", and I said zero'd to a tenth, not zeroed to 10 thousandths.



I don't even know if anyone currently makes an indicator that reads as crudely as a 0.010" graduations, 0.001" is the coursest measurement I'm familiar with for indicators.

I didn't feel insulted. Thanks for thinking of me though.

Mishka, We know the accuracy that we get from the Manson and making other people understand that a vertical barrel held by a vise with the collet snug in the barrel has less chance of being out of center than those in the Lathe is not an easy task. The Lathes that my father used cost Hundreds of thousands of dollars. They still had some runout. Barrels are NOT round and holes are not centered. The proof is in the pudding. My 25-06 shooting reloads when it was newly built and Lathe crowned shot 1/2 MOA at 300. Over the years and many rounds later it open up to about 2.5" at 300. We crowned this rifle with the Manson and the group size went to 5/8" at 300 yards with the same reloads. It is a 700 action trued and has a Shilen 26" heavy sporter contour barrel,a polished old style Remington trigger set in a Brown Precision fiberglass stock accra glass bedded. It is not Fancy, But it shoots with a Manson Crowned barrel. It has an older Swarovski scope on it. If I thought for a minute that I could improve on that I would . But I don't have the Money to buy the Lathe that it would take to improve on Perfection. After crowning 50-100 rifles we have seen awesome improvement on most. My shooting Buddy perchased the Tool to do some Military rifles originally. We now have one of each collet that Manson makes . The cutters are so sharp that after shooting 30 or 40 rounds one can look through a set of loops and see a pefectly even powder ring around the bore.

I'm suprised your rocket scientist machinist father never heard of a 4 jaw chuck?

During the time of the space program, lathes costing 100's of thousands of dollars would have been extremely large lathes, bed lengths that are measured in feet and not those that would be used to work on a rifle barrel.

I can assure you if one was to use a toolroom lathe from those days, say a Monarch 10EE, that they would be able to hold exremely tight tollerances, much tighter than a piloted cutter.

I'm not saying a good crown can't be cut with a manson cutter, but to say that a lathe can't cut a concentric crown is shows a great deal of ignorance on your part.

BTW, how can that highly accurate manson cutter be manufactured, if not for one of those highly inacurate lathes? Ponder that one obywan.

Of all the Bench-Rest records that have been set over the last 50 years , were the crowns cut on a Lathe or Hand Operated tool? Does anyone know the answer to this? My bet would be a Lathe