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How does one measure a barrel; groove to groove or land to land?
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Micing Barrels
- Thread starter Marc Adamchek
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To fully measure the important things measure both.
If you are trying to find the caliber measure land to land.
This is pretty easy with the newer barrels that have an even number of grooves.
If it is an old barrel or one made using the old method of cutting the grooves with a single tooth cutter it will have an odd number of lands like 5 or 7.
For the average guy using common measuring devices like dial calipers it is almost impossible to measure land to land because there will be a groove opposite each land.
If you are trying to find the caliber measure land to land.
This is pretty easy with the newer barrels that have an even number of grooves.
If it is an old barrel or one made using the old method of cutting the grooves with a single tooth cutter it will have an odd number of lands like 5 or 7.
For the average guy using common measuring devices like dial calipers it is almost impossible to measure land to land because there will be a groove opposite each land.
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You're right, Zonie, it's a tough hassle and it seems like it shouldn't be. All I really wantg to do is get a reading for ball/patch combos, bulllet size, just basic stuff.
Also, The dial calipers are ground down about halfway, making a small (very) kind of notch. I'm assuming that THIS is the spot to, for lack of a better word, hang on the muzzle to get a consistent measurement of the inside. Am I making any coherent sense here or am I just too tired and inexperienced (probably BOTH)to get it across?
Also, The dial calipers are ground down about halfway, making a small (very) kind of notch. I'm assuming that THIS is the spot to, for lack of a better word, hang on the muzzle to get a consistent measurement of the inside. Am I making any coherent sense here or am I just too tired and inexperienced (probably BOTH)to get it across?
paulvallandigham
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The inside measuring blades on the dial caliper are beveled to give you strength where its needed, but a near- knife blade width to insert into small bores to get an accurate measurement. Other wise, you would have to slug the barrel( A royal PITA, by comparison, IMHO) and take your measurements off the slug you pull out of the barrel.
Insert the " jaws" for the inside measuring of the calipers into the muzzle, and, for the lands, set one jaw on one land, and the other on a land opposite of it. Take a reading. Then move the jaws to the grooves next to the lands and take that larger measurement. Write them down. Subtract the bore diameter( Land to land) from the groove diameter, divide by 2, and you will now have your groove depth. Depth is important when buying patch material, as you want fabric that is thick enough to fill those grooves complete.
In fact, because lubed cotton fabrics will compress at least 1/3 their thickness, when loaded in the barrel, I look for fabric that is 150% of groove diameter. If your groove depth is .010", then look for .015" thick fabric, or thicker, depending on the ball diameter you intend to use. :thumbsup:
Insert the " jaws" for the inside measuring of the calipers into the muzzle, and, for the lands, set one jaw on one land, and the other on a land opposite of it. Take a reading. Then move the jaws to the grooves next to the lands and take that larger measurement. Write them down. Subtract the bore diameter( Land to land) from the groove diameter, divide by 2, and you will now have your groove depth. Depth is important when buying patch material, as you want fabric that is thick enough to fill those grooves complete.
In fact, because lubed cotton fabrics will compress at least 1/3 their thickness, when loaded in the barrel, I look for fabric that is 150% of groove diameter. If your groove depth is .010", then look for .015" thick fabric, or thicker, depending on the ball diameter you intend to use. :thumbsup:
ohio ramrod
75 Cal.
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Land to land can be measured accurately with what old time machinists called "hole gauges" They were a set of expanding probes that you would tighten in the barrel and then remove and check with a micrometer. You can make one fairly simplely if you have a lathe. Send me a p.m. if you want detailed instructions. grove to grove can be more difficult on odd groves for even groves most dial calibers will give you an accurate reading. But the simplist method for odd groves is to measure the thicknes from flat to land and flat to grove. The difference is the grove depth. This method depends on concentricity of flats to bore to be accurate.
paulvallandigham
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If you go around the 8 flats and measure all of them, you can use the average to get an idea what your groove depth will be.
Otherwise, if you can't or don't want to remove the butt plug from the barrel, you can put a heavy brass rod down the barrel, then oil the bore, and hammer an over-sized Round ball down the barrel far enough that it begins to move easily. You want a ball that is at least as wide as your groove depth, so that the grooves are completely filled with the soft lead.
Tip the barrel up over a pile of rags or newspaper to catch the slug, and shake the barrel so that the heavy brass rod pushes the slug back out of the barrel. The Lands will appear as "Grooves" in the lead slug, while the grooves of the bore will appear as the "lands" on the bullet.
Now you can measure the bore and groove diameters with the micrometers already pictured here. If you don't have these tools, call local machine shops to find one. Most will be intrigued to see your gun, and won't charge you a dime to measure your slug.
Otherwise, if you can't or don't want to remove the butt plug from the barrel, you can put a heavy brass rod down the barrel, then oil the bore, and hammer an over-sized Round ball down the barrel far enough that it begins to move easily. You want a ball that is at least as wide as your groove depth, so that the grooves are completely filled with the soft lead.
Tip the barrel up over a pile of rags or newspaper to catch the slug, and shake the barrel so that the heavy brass rod pushes the slug back out of the barrel. The Lands will appear as "Grooves" in the lead slug, while the grooves of the bore will appear as the "lands" on the bullet.
Now you can measure the bore and groove diameters with the micrometers already pictured here. If you don't have these tools, call local machine shops to find one. Most will be intrigued to see your gun, and won't charge you a dime to measure your slug.
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Bore mikes work well. They have multiple axially oriented elongated contacting surfaces that project outwards and press against the inside of the hole being measured. This is my ArmiSport 1847 being checked out. The bore is .696". Grooves are between .003"-.004" deep.
http://i791.photobucket.com/albums/yy192/SNARGLEFLERK/boremikes.jpg
http://i791.photobucket.com/albums/yy192/SNARGLEFLERK/boremikes.jpg
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Zonie, Zonie, Zonie--MANY THANKS for reminding me the only tool I have at my disposal is dial calipers I bought from Midway years ago. I meant to mention that but forgot to. You seem to have picked up on that, though, so maybe it's not the end of the world I forgot to add this point in.
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I'm spaced out from being online too long and starting to forget what I've written and so re-writing the same thing a different way and......Anyway, I'm with Hogghead: where can I get such a cool tool?
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Hogghead said:
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GoodCheer please check out this link and let me know if this is the tool you are talking about. And any information on using one would be helpful. Thanks, Tom.
http://www.starrett.com/download/277_p225_230.pdf
http://www.starrett.com/download/277_p225_230.pdf
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Yep, that's the type. Some have three contacts that come out, some four, some even more.
There's another type that has three ball bearings pushed outwards by a spring loaded tapered inside rod. Has a dial indicator at the handle.
Like everything, each has it's limitations. For example, three contact points spaced 120 apart would be pretty useless on a barrel with an even number of grooves unless divisible by three.
There's another type that has three ball bearings pushed outwards by a spring loaded tapered inside rod. Has a dial indicator at the handle.
Like everything, each has it's limitations. For example, three contact points spaced 120 apart would be pretty useless on a barrel with an even number of grooves unless divisible by three.
Which one do you think would work best for using on barrels from 22 to 50 caliber(if that is possible). If you have the time. I realize that is alot to ask. But if you have the time please keep in mind that I would like to keep my cost down. However if a particular one would work well then I might be able to find a good used one somewhere. Thanks again for all your help. Tom.
I've had good luck with Cerrosafe. It's intended for measuring chamber length on cartridge rifles, but it works just as well for slugging muzzleloader barrels.
For those unfamiliar with it, Cerrosafe is a 'metal' that melts at around 190 deg F. You pour it in the barrel (you first need to block the barrel with a thick wad on a string or wire) and then when it hardens pull it out and measure it like any slug. It's available, with instructions, from Brownell's.
For those unfamiliar with it, Cerrosafe is a 'metal' that melts at around 190 deg F. You pour it in the barrel (you first need to block the barrel with a thick wad on a string or wire) and then when it hardens pull it out and measure it like any slug. It's available, with instructions, from Brownell's.
mykeal said:
+1 to that! The stuff is too easy to use. It melts at less than boiling water temps. It's a bismuth alloy.
http://www.trackofthewolf.com/Cate...Id=2&subId=204&styleId=1074&partNum=CERROSAFE
Pour it, it shrinks the first 1/2 hour, then regains full/actual size in 1 hour and maintains that size for 24 hrs before shrinking again, (There are charts)
But on a side note, unless it's a chunk or bench gun that's going to be loaded to the tenth of a grain powder each time and each and every patch section is going to be mic'ed and selected for consistancy,,knowing exact land and grove diameter to the nearest .001 is kinda mute a common PRB combo, the patch is there too "impart" the rifling to the projectile and is by far the easiest/most flexable variable to the mix
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I have about 1-1/2# of Cerosafe. I have used it before. But you need to be careful and take into account its shrinking properties. However we cast for a lot of different MZ's, and CF's. I just think a mic would work great, and be easy to use. Just an opinion. Tom.
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Which one do you think would work best for using on barrels from 22 to 50 caliber(if that is possible). If you have the time. I realize that is alot to ask. But if you have the time please keep in mind that I would like to keep my cost down. However if a particular one would work well then I might be able to find a good used one somewhere. Thanks again for all your help. Tom.
Each set of mikes generally does not cover a very broad range. Trying to cover .22 to .50 would get really pricey with multiple sets of tooling.
Slugging the bore and measuring the slug is the tried and true method because of it's utility; just one measuring tool for outside diameter measurements of any slug.
Finding one set of bore mikes that spans the range of fifty to fifty-eight would be a real treasure. That's something to keep my eyes peeled for.
Each set of mikes generally does not cover a very broad range. Trying to cover .22 to .50 would get really pricey with multiple sets of tooling.
Slugging the bore and measuring the slug is the tried and true method because of it's utility; just one measuring tool for outside diameter measurements of any slug.
Finding one set of bore mikes that spans the range of fifty to fifty-eight would be a real treasure. That's something to keep my eyes peeled for.
daperdon69
32 Cal.
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There is another way to get the dia's in question with out buying expensive ID. mics, or slugging the barrel with odd numder of lands. You might try useing a plug gauge the same size as the bore. Slide the pluge into the bore then use shim stock in .001 increments to find the land depth. (Kind of like checking your spark plug gap) Times that by 2 and add to the plug gauge dia. Now you have both sizes.
If you need a gauge pin made, make it out of brass.
This is just another idea to try to get you in the ball park with out pushing lead down the bore or buying special mics. other than your dial caliper.
You could make a casting of the depth with say clay, and measure the depth with your caliper? Then do the math.
Never tried this, but dosen't cost any thing to try.
Good luck, Tradegunner
If you need a gauge pin made, make it out of brass.
This is just another idea to try to get you in the ball park with out pushing lead down the bore or buying special mics. other than your dial caliper.
You could make a casting of the depth with say clay, and measure the depth with your caliper? Then do the math.
Never tried this, but dosen't cost any thing to try.
Good luck, Tradegunner
