Pin gauge length/brand?
- Thread starter eddief
- Start date
JerrySharrett
Senile Member
Pin gages (or deltronic) are fine for roughing in the bore then finish dialing in using a good quality dial indicator and indicate in the bore at the point that is most important to accuracy. On the chamber end that would be in the chamber throat area and at the muzzle at the bullet exit area.
Knowing that all barrels have some curve in the bore why would you want to dial a barrel in at points outside the barrel???
Mike Bryant
Active member
I'm not so sure that you actually need a full set of pin gages for each caliber as long as you are just using them to just rough in the bore and then go on in and indicate at the projected throat with a long indicator point directly on the barrel. I have a set of Meyer's and several sets of Deltronic's. I normally start with the center pin and use it to rough in the bore. If it won't go in, then I drop down to one that will. It is pretty easy to use the pin gage to help select the pilot size that you need to use on the reamer. You can do that with the pilots, but the pin gages are quicker to use and make selecting the correct sized pilot quicker.
Butch Lambert
Active member
I use Deltronic pins and have a set for each caliber that I chamber. Check with http://www.crescentgage.com/productlines.htm. I buy from them and they are great to deal with. I buy the 25pin sets. If say your 6mm barrel has a mean of .237 bore-the set will have the .237 in the middle and 12pins over and 12pins under. This will give the range from .2358 to .2382.
Butch
Butch
Pete Wass
Well-known member
Pretty tough to work in tenths when turning things in a lathe. PLUS, I think gauge pins are hardened but don't know for sure. I do know they are ground true.
Sort of on this subject: I have a Range Rod which I have had for a number of years and is still un-used. I have recently geared up to do some barrel work and the other day when I was at my shop I stuck it in a barrel. I realized it had the ability to have bushings of various sizes attached to it. I have the bushings but got to thinking, "What happens to the part hanging off the bushing when one is indicating a barrel in? There is bound to be some slop in the junction betwin the bushing and the rod, no?
Sort of on this subject: I have a Range Rod which I have had for a number of years and is still un-used. I have recently geared up to do some barrel work and the other day when I was at my shop I stuck it in a barrel. I realized it had the ability to have bushings of various sizes attached to it. I have the bushings but got to thinking, "What happens to the part hanging off the bushing when one is indicating a barrel in? There is bound to be some slop in the junction betwin the bushing and the rod, no?
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Butch Lambert
Active member
Pete,
You will find it is about .0002 or more under. Deltronic pins are hardened and ground. I have a couple range rods with bushings. I've asked several people to indicate their range rods, Indicate your work in with it, Remove it and reinsert it. What do your indicators show now?
Butch
You will find it is about .0002 or more under. Deltronic pins are hardened and ground. I have a couple range rods with bushings. I've asked several people to indicate their range rods, Indicate your work in with it, Remove it and reinsert it. What do your indicators show now?
Butch
The roller on a range rod is just that, a roller. Sure it's a bushing, and you've got to make sure it fits in the bore but other than that its function is the same as that of an indicator stylus, except with a roller instead of a ball..... in other words it will ride against one side of the bore..... on purpose.
Anyone attempting to float one on the middle of the bore and finding the "slop" is misusing the rod.
opinionsby
al
Anyone attempting to float one on the middle of the bore and finding the "slop" is misusing the rod.
opinionsby
al
D
Dennis Sorensen
Guest
Gauge Pins vs Range Rod
Pins are a constant diameter (not tapered). They were designed to measure the diameter of a hole.
Pins measure over their entire length.
Range Rods have a removable pilot and the rod itselt is tool steel and ground with a 1 degree taper.
Range rods measure at the pilot and at the point of contact wherre the diameter grows to the same diameter as the rod. It measures at two distintctly different points.
Just as Butch has described buying a set of pins in .0002 increments pilots should be purchased in such increments.
Properly used range rods measure over a distince varing from 1." to about 2."
Range rods are not technically used to measure the bore diameter at the top of the lands.
Nat Lambeth
Pins are a constant diameter (not tapered). They were designed to measure the diameter of a hole.
Pins measure over their entire length.
Range Rods have a removable pilot and the rod itselt is tool steel and ground with a 1 degree taper.
Range rods measure at the pilot and at the point of contact wherre the diameter grows to the same diameter as the rod. It measures at two distintctly different points.
Just as Butch has described buying a set of pins in .0002 increments pilots should be purchased in such increments.
Properly used range rods measure over a distince varing from 1." to about 2."
Range rods are not technically used to measure the bore diameter at the top of the lands.
Nat Lambeth
Mike Bryant
Active member
The Deltronic pin sets that I have are in .0001" increments. I do have a set in .0005" increments that I use for checking neck diameters on .22's and 6mm's. The 6mm set will check neck diameters from .261" to .2725". It makes it nice to know that a .2620" pin will fit in the neck and a .2625" pin won't after you've chambered a .262" neck PPC. The pin sets in .0005" increments come in sets of 24 pins. The sets in .0001" increments are 25 pin sets. With either set you specify the mid range size that you want when you order them and go from there. The 6mm set that I have for indicating bores has a .2365" mid range. I haven't had any barrels larger or smaller than what the set would accomodate. You can certainly chamber barrels without having pin gages, but they will help you indicate a barrel in faster and as it's said "time is money".
My sets are not as good as Mike's.
I have been buying MSC .0005" increments with the + and - versions that are within .0002"
http://www1.mscdirect.com/CGI/NNPDFF?PMPAGE=1376&PMITEM=88927652&PMCTLG=00
I just buy them when I have a barrel that the standard .001" increment pins to not fit perfectly.
So far that was just for .257 and 7mm:
88927652 .2765+ CLASS ZZ GAGE 1 2.8700 $2.87
89027650 .2765- CLASS ZZ GAGE 1 2.8700 $2.87
89025050 .2505- CLASS ZZ GAGE 1 2.8700 $2.87
88925003 .2500+ CLASS ZZ GAGE 1 2.8700 $2.87
I have been buying MSC .0005" increments with the + and - versions that are within .0002"
http://www1.mscdirect.com/CGI/NNPDFF?PMPAGE=1376&PMITEM=88927652&PMCTLG=00
I just buy them when I have a barrel that the standard .001" increment pins to not fit perfectly.
So far that was just for .257 and 7mm:
88927652 .2765+ CLASS ZZ GAGE 1 2.8700 $2.87
89027650 .2765- CLASS ZZ GAGE 1 2.8700 $2.87
89025050 .2505- CLASS ZZ GAGE 1 2.8700 $2.87
88925003 .2500+ CLASS ZZ GAGE 1 2.8700 $2.87
Joe Ponto
New member
The set I have is the .0001 set....
Pete Wass
Well-known member
The underlying message here
seems to be that a Range Rod will not give one a true indication that they have their barrel centeres in the lathe, is this correct? If so , that would mean that one should use pins in both end of the barrel to true it up?
I surmised the purpose of a Range Rod was to be able to true the bore up to the spindle at the breech end only, is this not so? I think there are a lot of winning barrels being made up by folks using Range Rods, No?
seems to be that a Range Rod will not give one a true indication that they have their barrel centeres in the lathe, is this correct? If so , that would mean that one should use pins in both end of the barrel to true it up?
I surmised the purpose of a Range Rod was to be able to true the bore up to the spindle at the breech end only, is this not so? I think there are a lot of winning barrels being made up by folks using Range Rods, No?
The effect of bullet tilt in ammunition is up to 2moa before the chamber bends the 30-06 cartridge straight, per what Abbatiello wrote in the American Rifleman decades ago.
Centering up the chamber is not nearly as important, because while the ammo's eccentric bias may be inserted randomly, the chamber's bias is always the same.
I cut off the threads on a 7mmMag barrel with a cut off tool and did not de burr.
When I put in the reamer, the burr got the reamer started off center.
The reamer had .0050" of wobble all the way to headspacing.
That rifle shoots sub moa.
What does it all mean?
You could chamber winning barrels without dialing them in, jut put them in a 3- jaw.
Centering up the chamber is not nearly as important, because while the ammo's eccentric bias may be inserted randomly, the chamber's bias is always the same.
I cut off the threads on a 7mmMag barrel with a cut off tool and did not de burr.
When I put in the reamer, the burr got the reamer started off center.
The reamer had .0050" of wobble all the way to headspacing.
That rifle shoots sub moa.
What does it all mean?
You could chamber winning barrels without dialing them in, jut put them in a 3- jaw.
Butch Lambert
Active member
Sub MOA, depending on how much sub Moa might be way too large to place.
Butch
Butch
The function of a range rod is the same as the function of a dial indicator..... it doesn't "measure" much of anything most of the time, it just shows wobble and because of this, YES it most certainly does show you when you're centered up. And if you drive it up and down the bore looking for and eliminating wobble then you have to be centered to the best of the ability of the chuck support.
There are no "measurements" involved in this.....nor repeatability. Any more than there's repeatability if you swing your dial indicator out of the way and then reinsert it.
al