Maybe I don't understand the problem, but in lieu of an expensive device to measure barrel wall thickness,(some of which are worthless) why not just measure the inside diameter of the barrel then use a simple micrometer to measure the outside diameter. Half of the difference between the two is barrel wall thickness.
I don't want to but the knock on Midway, but I think some of their videos should be taken with a grain of salt.
No guarantee of bore and outside wall concentricity is why each wall must be measured multiple places.
Yes, multiple measurements is a must, but it just as easily done with a mic.
pooch, your suggestion can be used as a rough guide,HOWEVER,
concentricity is one problem, the other is that an outside micrometer,because of the rib, cannot measure the outside wall accurately,and this is often the area that suffers most from dents etc. and thin spots are found.
It is not uncommon to find a gun out of concentricity by .015".
Your .032" minimum wall thickness may be only .017"!
A true wall gauge is the only way, anything else is deeply flawed with meaningless results.
Barrel wall measurement under the rib cannot with any device I am familiar with. A barrel bored off center by .015 would most likely fail initial proof. A Spanish gun may be the exception.
I am currently polishing a barrel whose wall thickness varies from .025to .040 at the same point. The manner in which it was struck at the factory or repaired later on can make a huge difference in thickness that cannot be discovered without a wall thickness gauge.
Barrel wall measurement under the rib cannot with any device I am familiar with. A barrel bored off center by .015 would most likely fail initial proof. A Spanish gun may be the exception.
You are right, Pooch. However, barrels were frequently heavily struck after they had been joined. Therefore it is most likely that the barrel under the rib is thicker than any other part.
You need access to the inside and outside of a barrel to measure its thickness, unless you have a rather complex X ray instrument that can take slices. The barrel thickness inside the rib presents the same problem to the barrel wall thickness gauge as it does to the simple micrometer.
A .015 off center would show up when you are micing the outside, if were only at one point. To be .015 off and not picked up by the outside mic, the barrel has to be bored .015 off center the length of the barrel. Since we are usually investigating guns that nearly 100 years old it difficult for me to imagine a barrel wall initially being .020 and not have failed by now.
$95.00 for a wall thickness gauge. The bore micrometer and the vernier caliper or micrometer used to measure the "difference" would cost you that much or more. The $95.00 wall thickness gauge would also give you the true measurement. Sorry, Pooch, you're no machinist.
The $95 gauge from Brownells is a joke.
A $500 galazan gauge or hosford gauge is not, however.
A real gauge gives real measurements. I would not be interested in owning a gun measured using the Pooch method. The odds of misrepresentation are too high.
Only a real wall gauge is going to measure accurately at the depths necessary to know a gun is safe. A .015" reading at the muzzle of a cylinder bore is irrelevant to safety, a .030" guesstimate 10" from the breech is not trivial.
Get the right tool for the job.
to be safe and sure, take your barrels to an old time smith who has the tools and experience to do the job.
I agree with Rookhawk. The Hosford gauge is the way to go, but one has to understand the data it generates. It is real good for measuring the depth of pits too. Pooch, I see in your biography you work for Cabelas. Surely, as many English guns and others going through Cabelas, they have a gauge. If not, you should be able to talk them in to buying one. They are a very useful tool and pretty easy to use. I wouldn't buy a vintage gun without measuring up the barrels. It is clearly the smart thing to do when contemplating a purchase of any old gun.
They have been pretty lucky so far. But the decisions come down from Corporate where there are no engineers and my voice is not big enough to reach Corporate. We were sent the $95 special for wall thickness, which does more harm than good. The Hosford is a decent instrument but it's still not checking the wall thickness beneath the ribs. The best of the mechanical measuring devices are still a bit dodgy because of the difficulty controlling the tension on the support rods.
Ultrasonics are used on turbine blades and barrels can suffer a similar abuse, just not as extensive. The Chinese are producing some pretty cheap ultrasonic testers, maybe that will be a future tool for gun barrel wall thickness.
Nah, cabelas is blissfully ignorant. I bought a Ferlach from them and it had 2.75" chambers.
I measured it in there store when it got shipped in and it measured .015" minimum walls for quite a length of the gun. It had been shot with steel and someone tried to hone out huge flaws.
I showed the Cabelas management the issues and demanded my money back. I also demanded they disclose the deadly flaw in the gun to all customers. They said "yeah, sure". 3 months later it was back on their website and then sold to an unsuspecting victim.
Cabelas does not measure, nor do they pay a premium for good walls on guns. Every dodgy gun in the country gets pawned off on them.
This is my take-off of the Galazan gage. I can measure 10 and 12 ga. on one rod and 16 and 20 ga. on the other. In 12 ga. with very tight choke around .690 I cannot put it muzzle down as it will not fit over the rod with the ball. I can measure 15 1/2" from breech end.
I put a level on mine mainly for 10 ga heavy wall barrels in doing muzzle end with all the weight now up, especially in the first few readings.
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In my opinion, to use the Hosford type gage, you really have to know what you are doing in measureing the breech end because of the weight on the bar. It would have to be measured more than once to get the right feel.
If I wanted to change the digital dial out to a Starrett, I could use a variety of tips and one is a needle tip if I wanted to get that critical next to both ribs.
I don't know how reliable a micrometer would be on the outside in combination with a dial bore gage.
I forgot to mention on doing 10 ga barrels with the muzzle down. The aluminum gage in the box is a 10 ga chamber gage with a spirit level mounted in it. When the base is level and the barrels are mounted and the muzzle end is in the tapered collar (brass) then I insert the chamber spirit level and then measure from top rib to bottom rib usually in 3-4" increments. Takes a while but then I know what I have.
We have collected a bunch of junk. They came and got me to help in this area, but without the right tools and without everyone using them I don't think much is going to change.
I've been trying to design something using a laser and a mirror to align things but I think the ultra sound will be the system of the future.
JDW how do you set your zero? Do you secure the barrel at both top and bottom?
There is a ball bearing that is in the shaft opposite the spring loaded arm. Zero is set each time and then rechecked.
The barrel whether I am measuring the muzzle end or breech end, fit into a tapered cone to center the barrel.
I mainly do L.C. Smiths and had to make the cone longer for measuring the breech end so that the extension rib did not hit the cone when rotating barrel to get readings.
Pooch was wrong about measuring the outside of barrels to determine wall thickness, and he is wrong again when he says the Manson gauge is a joke. It is not a joke if you know how to use it. The vertical method has quickly become obsolete, even when used with the Gaddy modification. There is a step by step explanation of how to use the Manson in the most convenient and accurate method on the PGCA forum in a thread titled "Barrel wall thickness" page 5. The thread is in "General Parker Discussions".
eightbore do you know how to find the distance between two circles?
Pooch,
The question is: do you know how to measure the distance between two ellipses? Exactly.
That's the problem.
You need a real wall gauge. The concentricity and out of round issues are too great to ignore.
Pooch, good luck--but I think you're fighting a losing battle at Cabela's. I do think most of the Gun Libraries now have bore gauges, and at least some of the guys who work there know how to use them. But that has not always been the case. I know they measure wall thickness at Sidney, and I think at Scarborough with Jack Dudley, but not in many other stores.
It is real good for measuring the depth of pits too.
That's a good laugh
Pooch replied to my offer of instruction on the Manson gauge by posting a sarcastic comment. I will repeat my earlier statement, "Pooch is no machinist." The post I referred to on the PGCA forum is a clearly written block of instruction on use of the Manson gauge. If Pooch decides not to take advantage, he has met my expectations.
It is real good for measuring the depth of pits too.
That's a good laugh
You know what Joe, you might be right, but the gauge is better than nothing at giving an estimate of the depth of a pit. You could, however, be a little more diplomatic in your response to a statement you disagree with. I think patronizing and downright sarcasm is a most unbecoming trait, at least so in a learned individual. But, at any rate, thank you for the correction.
buzz, to give you an answer better than jOes, there is no way to measure the depth of pits using any type of dial gage. I do have different tips to use on a non-digital gage, one has a needle point, but if the pit was a few thousanths deep, it would get caught in there and mess up the rest of the readings.
Thanks David. Your response make sense. However, and for what it's worth, Kirby Hoyt who sells the Hosford gauge, describes it in his advertisement as being able to measure the depth of 'some pits'.
I'm an engineer or was, but the answer is simple school boy math. One draws a line to the center of each circle. Then at the tangent point, where the lines intersect the arc, draw lines perpendicular to the line connecting the centers. The distance between the two parallel lines is the distance between the arcs in question. As for arced, irregular surfaces any three points can be projected with tangent points to get the center of any arc in question. The key words here are perpendicular, parallel and straight line relationships. These require fixed points and fixed relations preferably ones at 90 degrees.
The Manson or tuning fork device method of one chap holding it on a string while the other chap rotates the gun barrels in a circle. Might provide the accuracy for two monkeys to peel an apple, but is not the stuff of accurate measurement.
The management threw us underlings a barbecue dinner last night. Seems we who are number 37 in Library size are continuously ranked in the top five in volume of sales and profit. There are some changes in the works planned to take us to the top. This means moving lots of guns and the pitch is simple - to the customer selling his gun, he's told - This what I can sell it for, this is the margin I need. The boss's rule, we don't make killings, just margins. We need guns to move them.- Why put out $20,000 buying a prestige gun that will take a year to sell when you can buy 10 guns at $200 each and turn that money over a couple dozen times in a year.
It's fun, makes sense and I like it.
Pooch,
Here's how much ground I'll give you in this debate. The manson guage is mediocre. If you had a gun in your hands that was being sold for $20,000, and it was YOUR $20,000 on the line, you can follow the instructions provided over the course of say an hour and properly blueprint the entire pair of barrels. No one working retail at Cabelas with the pressure of customers, noise, and the fact that it is other people's money is going to make such measurements feasible with a manson gauge.
The classic gauge used throughout Europe's fine gun rooms (a.k.a. a Galazan gauge in this country since they sell them) works very, very well. I can get accurate measurements within a minute or two. For a methodical blueprinting of an entire pair of barrels, I can do it in 15 minutes or less.
Other people rave about the Hosford gauge and I've seen a very well respected gunsmith outworker to Purdey's use a Hosford very proficiently...It's just not for me.
Before I ever started buying best guns from private parties I bought myself a quality gauge so I know exactly what I'm dealing with. Call me anal, I just don't have big cash to throw around making measurement mistakes on guns I buy for my hobby. Thousandths matter significantly as to value and I do tire of some of my guns over time and may wish to sell or trade them in the future. Neither buyer nor seller deserve a lemon that is misrepresented.
As to Cabelas gun purchasing strategy, I'd call it the hall of rank amateurs. (minus perhaps Dudley up in Maine) I decided to unload a few guns and brought 12 in for evaluation. They offered me $1200 for a $5000 gun wholesale. (no deal) They offered me $1800 for a gun worth $12,000 wholesale, $20,000 retail. (no deal) They then offered me $2700 for a gun worth $2700 retail. (sold) They offered me $2500 for a gun worth $2500 retail, $1200 wholesale. (sold) They offered me a $1700 for a gun worth $1700 retail. (sold)
The pricing system is a bit Zaney for me and definitely erratic. You certainly have to be able to control emotions as you hear the offers because the pricing is so very erratic. Knowledge is shallow as are the appraisals. Much easier to sell Cabelas cheap guns for full retail than best guns for 1/4 retail. A gauge would go far to help out the outfit if they knew how to price guns based on whether in proof and with thick walls.
When it comes to fine guns we, at my Cabelas, are amateurs. We are being successful at our store because we realize that fact and understand our markets. We sell to ordinary folks and strive to provide them a decent gun at a decent price. Most of the folks working the Library were buyers at other stores so they know their limitations. Cabelas is a big box store, the stuffed animals, the fancy gun library are just tools to make ordinary folks feel special. If we make our customers feel special they come back and they buy things. It's not about being a gun expert it's about maintaining a consistent profit margin, and return customers.
WE don't deal in fine guns, we have a few nice ones, but mostly we just sell guns to be used. My contention is I can get better indication of barrel wall thickness with a caliber and a good bore gauge then I can with a Manson. There are lots of indications of a thin barrel wall. Dents, the rings in the bore, the feel of the gun. These aren't the accuracy required to deal in fine guns but they are a good indication of when it's time to run.
buzz, If they are that big, then you can see them and they will be dark (deep shadow) and yes you will feel the tip of the needle passing over them, but measureable......maybe a few thousandths.
The only difference in the Hosford gage is that you use it horizontal, as to being better... Mine is too heavy to be carrying around to different tables. If the seller does not have the wall thichkness written down showing this gun, and does not give you a few days to do so, then you are at his mercy.
As eightbore showed in his use of the gage, you really need two people to use the Hosford gage accurately.
Mine like the Galazsn one, I can rotate the barrels at the same spot and read from top rib to bottom rib and then move the cone and do the same and then flip it over and do the muzzle end.
If its all about the profit margin and return customers you should not accept consignments or purchase guns for resale that require an attention to details that you are incapable of dealing with.
How do you attach the tension spring on the interior leg? I have been thinking a tension spring and a method of making the barrel wall perpendicular to the gauge would be a way to turn that Manson into a real instrument.
"Tuning fork" gauge with the Gaddy tension spring opposite the anvil on the interior leg and suspended vertically DOES produce repeatable measurements. Depth of a pit cannot be "measured" but the thickness of barrel wall (including some oxides to be sure)in the pit can be with an indicator tip that will enter rather than bridge the pit. Wall thickness adjacent to the pit can also be measured. Obviously "depth" of the pit can be extrapolated: WT adjacent - WT @ pit = Depth of pit. You have to be cack-brained to believe that the indicator can't "read" the presence of a declivity/irregularity/anomaly in the barrel wall! Obviously, whether the depth of a pit can be determined depends greatly on the size of the pit and very shallow pitting is usually detected only as physical chatter or vibration in the instrument and the indicator needle. I have yet to read the New Gospel according to the Parker lads but should be interesting.
jack
Correction to above: "indicator tip" should be "anvil on interior rod." With a bearing ball of any appreciable size as the anvil, Pooch and others are right that you can't get the anvil into a very narrow pit. You certainly can get a 1/8-3/16" diameter bearing ball to drop into a larger area of pitting and you can extrapolate the depth. The idea that a "needlelike" anvil can be calibrated to a ball-end indicator tip is no more ridiculous than the opposite but I have to admit that is not how my gauge is constructed. My face is a bit red for confusing which leg of the caliper goes in the hole! One should make sure one is not waxing geriatric before waxing theoretical.
Sorry pooch, I wanted to add to post, double-posted, deleted the first and then found your response. Few yrs. back, there were several threads on this subject which discussed Oscar Gaddy's [now discredited?] piano wire tension spring. They may still be archived or perhaps the langoliers have done their work. A number of us followed Gaddy's lead by modifying commercial guages or scratchbuilding our own to include the spring. Look at the photo of JDW's "table" gauge. The brass rod pivoting in a slot cut in the interior rod and no question hiding a coil spring behind is the same principle for the same purpose with a different execution. I'll see if I can find a picture and will post if I can.
jack
Here is a pictue showing how tension is put on the interior wall of the barrel. Opposite of that is the ball bearing. The rod for the 10 ga and 12 ga is 5/8"=.625 the ball bearing is 5/16"=.3125. The spring loaded brass bar is tapered and so is the slot. When compressed fully it has to be the same size as the shaft, 5/8" and the side that the bearing is on has to be drilled to less than half the diameter. As it is I cannot measure muzzle end barrel wall thickness on very tight choked 12 ga. guns, say .690 and less because of this.
The tapered brass cone that slides on the shaft and held with the thumb screw centers the barrel. With the breech end down it does the same.
Since the bore of the barrel is not concentric to the outside, you will always get a higher reading on one side than the other, but still you will get an honest wall thickness reading.
Here is a picture of the spring loaded brass and the dial needle resting on the ball bearing.
These gages are fairly easy to make, if I had a milling machine it would be a cinch to make these. The hardest thing is making the tapered slot and I did it on a 20" drill press with an XY table feeding .002-.003 at the most each pass. It still shook sometimes like a dog shi-ting razor blades.
Any tool that will produce consistent readings is worth cost / effort.
The only way to measure pits (this topic keeps coming back) that might be available is an ultrasonic thickness gage. Relatively inexpensive ones are around, but will not do the job. It would take a high end instrument, one that measures coatings.
You can pick up an inexpensive bore scope. Then you can at least view the pits.
There are number of folks who have already posted on this thread. They know what they are talking about. This board is a good place to vet an idea, it is even a better place to learn. I am still learning from many here.
Pete
Thanks guys this is good stuff. I see a project coming on.
Rabbit, the Gaddy modification is not "discredited". It is just about impossible to use at a gun show or auction. Take the time to read my method. It was taught to me by Jon Hosford, who knows a little about shotgun measuring devices. One poster says my method requires two people. The vertical method requires a whole lot more help than that, not just a helper. I used the vertical method for a while, but never found a convenient place to hang the gauge at a gun show or auction. Another (Rookhawk) says my method is time consuming, would take an hour. I can measure a pair of guns in ten minutes, one gun in five, all results repeatable. His argument is that the Manson instructions cause him to think the gauge is "mediocre". Rookhawk has made a decision not to read the instructions on the PGCA site, which have no relationship to the Manson instructions. By the way, I never saw any instructions in the Manson box. I never did expect Pooch to read the instructions on the PGCA forum, but I expected better from Rookhawk. If you guys want to haul a Galazan table gauge to gun shows, be my guest, but my method and my Manson gauge will do the same job. I used the Galazan table gauge for years, but it never went out of the shop. Do you guys haul your table gauge to shows and auctions?
Here is a video of the Hosford gage. You need Adobe Flash player. Part Two is on the right, scroll until you see it.
A video is much easier to understand than words in my opinion.
Most all will work, the Hosford is a great tool to use at a show providing it is not to crowded and the seller lets you do so.
http://www.youtube.com/watch?v=1jQZn4kohH4&feature=relmfu
Eightbore,how can I access those instructions on the PGCA site? I having a hell of a time getting consistent readings from a gauge I bought. Thanks,justin
Why don't you stop picking on Ol' Pooch. Ol' Pooch did read the the instructions on the PGCA board, that's where I came up with the two monkeys trying to peel an apple analogy. With a Manson I've made enough readings to rate two guns within 10 minutes also and of the two dozen or so readings, one of them might actually be right. About the same success rate as two monkeys.
An eight bore is the diameter of a number 9 shot. The ramifications crack me up.
NOW a quick survey is space, time and ancillary equipment dependent? I thought that's the way it always was. A few yrs. ago Bill M. said he was getting by hanging the Manson from the tailgate on his rhino chaser. I guess that was only true for the camel jockey, shekels on the blanket, gotta run outside widit informality of Vintagers' events? I saw the Hosford demo'd at Pintail Pt. Beautifully-machined gadget but not particularly notable for a small footprint in use. I also had an opportunity to try a Galazan table gauge and neither the "hold your tongue just right" manipulation of barrels nor the repeatability of measurements impressed me despite being the time-honored design. Different strokes . . . .
jack
Justin, the instructions are on the PGCA forum, "General Parker Discussions" subforum. The thread title is as I stated on my post and it is on page 5 of that thread. I will not restate my instructions here, because several posters have made it clear that they will not read it. Maybe someone who thinks it is a good set of instructions will link it to this thread. I am trying to help people to read wall thickness in expensive shotguns for $95.00, not trying to get into a pissing match with people like Pooch. Benefit from my knowledge or don't. I'm through here. I am doing exactly what Rabbit did with his posts about the Gaddy modification. The only difference is that I'm getting shit from idiots who do not want to learn. Thank you, Rabbit for your information.
Thanks to the RevDoc for the link to the Murphy/Hosford material at PGCA. Bill, your instructions for use of the Manson WTG are similar to those given by Amarillo Mike for his "Truth" gauge a few months back. Obviously, the orientation of the gauge to the "in use" position for zeroing the indy is of first importance. After reading this, I see no reason why the inexpensive Manson could not be provided with a "third hand": a table hold down comprising a couple of pillow blocks and a shaft with an expanding mandrel one end and a crank the other for securing and rotating the barrel tube in the cantilevered horizontal orientation. As I recall Hosford has some sort of vise or holding appliance for his gauge.
jack
Here's the link to PGCA that Drew posted on p.1 this thread if you missed it.
http://parkerguns.org/forums/showthread.php?t=7889
I cannot say I agree that the manson gauge is without merit. While it does not offer the quality of measurement that either the Hosford or Galazan gauges do, it does offer a much better than nothing solution. Further the dial can be swapped for a digital one from harbour freight.
I admit it is not prefect, but it is far better than flying blind and I expect it is close enough to rule out borderline guns
Rabbit, you are right about the barrel holding situation. It should be a piece of cake to design some bracket to hold and rotate the barrels, eliminating the need for a helper. However, I measured a pair of second tier English game guns at an auction using a friend for a helper. He had never seen a Manson gauge before and had no trouble holding the barrels to the table for the ten minute procedure. As far as finding and maintaining "zero", the Manson, used horizontally with the eye hook, is as reliable as the Galazan table gauge or the Hosford.
Well, at the risk of a scolding from eightbore, the "Truth Tool" made by Johnathan Poole has been around for a dozen years at least and is the original horizontal tuning fork type wall thickness gauge and would appear to be much easier to use than the Manson. It was designed to be used in the horizontal position. Its upper fork is longer and can be hung in the end of the barrel when you are zeroing the gauge. The block has a hole in it that is large enough (1-1/2"?) to be hung from your thumb. It must be "hung" on the thumb so you don't torque the forks and throw off the reading.
It was $200 the last I knew.
I get repeatable measurements from it. On three different barrels I measured the minimum wall thickness with my Truth Tool and got within 1/1000th of Kirk Merrington's measurement. I measured them before I sent them to Kirk for some work.
Best,
Mike
Not a scolding, Mike, but I am very familiar with Jon Poole's Truth Tool. I was in Vegas at the Riviera when he introduced it to the American market. It is identical in use to the Manson tool. The Manson tool is zeroed while out of the barrel, holding the "ball" in one hand and the loop in the other. If you want to hang the Manson by the thumb, you can do it. You can put a block with a 1 1/2" hole in it or use a rope loop, like I do. The result is the same.
Having measured the same barrel on two different gauges I got a different reading of.001" . You can also get a discrepancy if the gauge is perfectly square on the table as the weight of the barrel "leaning" if only a fraction can give a false reading . Lets face it if a barrel wall measures .015" one gauge and .016 on another ,a .001" makes no real difference .
My recollection of various company's metrology (gauge calibration/cert) and inspection departments was that they would advise using an instrument capable of 1/10th the required tolerance. So, if you have a tolerance band of +/-.010", you should use an instrument capable of repeatable accuracy to .001". If you need +/- .001 on the part, you should use an instrument repeatble accuracy of .0001".
My Truth Tool is not accurate to 0.0001"(one ten-thousandth). But I have no doubt it is at least accurate to plus or minus 0.001" (one thousandth) which to my mind is adequate for my purposes.
I am glad though that you airplane guys are so anal retentive about accurate measurements. Mechanical failures at 30,000 feet while traveling 500 mph could really ruin a day.
Chuck of all people knows that the limiting factor of repeatable accuracy in long calipers is rigidity and that sufficient rigidity isn't available in most materials with a diameter which will slip inside a shotgun barrel of 12ga. or under. Did you go any further with your experiment with carbon composite as either arm of the WT gauge, Chuck?
jack
The main problem with most of these wall thickness gauges is they are supplied with a very cheap dial caliper. Once I got that figured out I purchased a high quality Starrett dial caliper from eBay. Since then my readings have been much more consistent and I have a lot more faith in the results. The Manson design has nothing I could fault, except at that price it would have to have the very cheapest gauge available.
Joe, I think you put an end to all of this one ten thousandth of an inch silliness. Thanks.
I did not read this whole post but have a Hosford gauge and do not regret the investment one bit.... great tool... on top of that, I thought my dog had stole my top lock downed piece and called them... they sent me a replacement for free... I later found it under the couch in my office and called them... they did want anything back and never charged me for the extra part....
