Inaccurate measurements from Stoney Point OAL Guage

[firstshot425]

I have one of the older "Pre Hornady" Stoney Point OAL guages. It is the one with the curved handle and a heavy metal wire for moving the bullet forward. For years, I have been using this guage along with a sinclair comparator tool to measure dist to lands and have never questioned the measurement results when actually seating bullets. I just took the OGIV measurement and subtracted 0.010 and used the result for seating the bullets. All the time thinking I was seating the bullets 0.010 off the lands.

Just on a wim, I took a 120g NBT and put it in the OAL guage, pushed it out a ways, measured the OGIV with the comparator tool and got a measurement of 2.030

I then used a hot glue gun to anchor the bullet to the modified OAL guage case, unscrewed the case & anchored bullet all the way off the OAL guage and measured it with the comparator tool. Low and behold, I got a measurement of 2.290. A 0.010 difference. What the heck?

I was able to duplicate this with several other bullet types. 145 Nosler SPT, 140 Sierra SPT, 140 Nosler Accubond and 120 Sierra SPT. In each case the actual OGIV (case NOT on the tool) was 0.010 less than the measurement with the case on the OAL guage.

In trying to figure out why, I noticed that when measuring with the case on the OAL guage, the metal wire that pushes the bullet forward was preventing the rear blade of the caliper from measuring at the center of the case head. In other words the thickness of the metal wire was raising the rear blade up slightly so that it was actually measuring on a slight angle instead of perfictly centered on the case head.

So, I'm thinking that all this time when I thought I was loading bullets 0.010 off the lands, I was actually loading them 0.020 off the lands.

Does this make sense? Has anyone noticed this before? Can anyone out there with this type of OAL guage duplicate my findings?

Thanks
firstshot

 

[stool]

just a guess..but the dia of your lands at the throat and the dia of the tool appear to be different.
the word is ogive....

have you tried a sinclair/hornady comparitor ?

 

[firstshot425]

just a guess..but the dia of your lands at the throat and the dia of the tool appear to be different. Don't understand this statement

the word is ogive.... Yea... I know.. fat fingered that one

have you tried a sinclair/hornady comparitor ? I'm using a sinclair comparitor and the old version of the hornady OAL tool

 

[firstshot425]

I just measured DTL for a 140 Sierra SPT using the stoney point OAL/sinclare comparator and got 2.207. (BTW this is the exact meaurement I got when I previously measured 10 random bullets)

So instead of backing off 0.010 as I normally would, I seated the bullet in an empty case to exactly 2.207. I then used a black Sharpie to blacken out the bullet, loaded it in the rifle, and closed the bolt. As I closed the bolt, I didn't feel any resistance as if the bullet had hit then lands and upon close inspection under magnifying glass, there were NO rifling marks at all on the bullet.

 

[bozo699]

Firstshot,
Throw that old school stonypoint tool away and do this right. Take a case and set the shoulder back .002 or more and give the neck about .001 tension, start a bullet into the case a ways then put it in your rifle and close the bolt. That will give you your jam length, you will see the land marks in the bullet, take a measurement of the marks and run your seating die down to where you think they will just about disappear when you seat the bullet. take oooo steel wool and lightly clean the marks off and seat the bullet further and then rechamber the round and again look for land marks, if your eyes are old like mine you will need a Jewlers Loupe, there cheap! after repeating this several times you will see one land mark disappear , then another disappear until you don't see them any more, that is when your just at the lands, once you learn it is pretty fast and deadly accurate! Wayyyyyyy more then the hornaday or stoney point. If your competing you need to sort bullets base to Ogive and you will need to do this with your different lots of bullets you have sorted. If your just trying to get a so so accurate hunting load then do what you been doing.
Wayne.

 

[stool]

please skip this method unless you are in to imprecise loading or have a optical comparator to measure the length of the jam into the lands.

Firstshot,
Throw that old school stonypoint tool away and do this right. Take a case and set the shoulder back .002 or more and give the neck about .001 tension, start a bullet into the case a ways then put it in your rifle and close the bolt. That will give you your jam length, you will see the land marks in the bullet, take a measurement of the marks and run your seating die down to where you think they will just about disappear when you seat the bullet. take oooo steel wool and lightly clean the marks off and seat the bullet further and then rechamber the round and again look for land marks, if your eyes are old like mine you will need a Jewlers Loupe, there cheap! after repeating this several times you will see one land mark disappear , then another disappear until you don't see them any more, that is when your just at the lands, once you learn it is pretty fast and deadly accurate! Wayyyyyyy more then the hornaday or stoney point. If your competing you need to sort bullets base to Ogive and you will need to do this with your different lots of bullets you have sorted. If your just trying to get a so so accurate hunting load then do what you been doing.
Wayne.

 

[dannyjbiggs]

Firstshot,
Throw that old school stonypoint tool away and do this right. Take a case and set the shoulder back .002 or more and give the neck about .001 tension, start a bullet into the case a ways then put it in your rifle and close the bolt. That will give you your jam length, you will see the land marks in the bullet, take a measurement of the marks and run your seating die down to where you think they will just about disappear when you seat the bullet. take oooo steel wool and lightly clean the marks off and seat the bullet further and then rechamber the round and again look for land marks, if your eyes are old like mine you will need a Jewlers Loupe, there cheap! after repeating this several times you will see one land mark disappear , then another disappear until you don't see them any more, that is when your just at the lands, once you learn it is pretty fast and deadly accurate! Wayyyyyyy more then the hornaday or stoney point. If your competing you need to sort bullets base to Ogive and you will need to do this with your different lots of bullets you have sorted. If your just trying to get a so so accurate hunting load then do what you been doing.
Wayne.

AMEN! And EACH time you reload a "lot" of ammo for that particular rifle.

Dan Biggs

P.S. As a corollary, I once spent my spare time fishing 'stead the rifle range...and I quickly learned that a lot of the lures presented, were more designed to catch fisherman...than fish !
Team Berger

 

[stool]

the dia of the tool you use on your caliper is a different dia than your actual lands at the throat.
the diff dia means you are measuring up or down further on the bullet......

when you say sinclair is that the stony point type caliper tool or their hex nut comparator ?...

just a guess..but the dia of your lands at the throat and the dia of the tool appear to be different. Don't understand this statement

the word is ogive.... Yea... I know.. fat fingered that one

have you tried a sinclair/hornady comparitor ? I'm using a sinclair comparitor and the old version of the hornady OAL tool

 

[stool]

now load a bullet at 2.212( 5 thou out) and see hat happens in the same test.

I just measured DTL for a 140 Sierra SPT using the stoney point OAL/sinclare comparator and got 2.207. (BTW this is the exact meaurement I got when I previously measured 10 random bullets)

So instead of backing off 0.010 as I normally would, I seated the bullet in an empty case to exactly 2.207. I then used a black Sharpie to blacken out the bullet, loaded it in the rifle, and closed the bolt. As I closed the bolt, I didn't feel any resistance as if the bullet had hit then lands and upon close inspection under magnifying glass, there were NO rifling marks at all on the bullet.

 

[Erik Cortina]

It doesn't matter which method you use as long as you get consistent repeatable results. Whatever measurement you come up with is just a reference point.

 

[firstshot425]

stool
That is exactly what I was planning to do, except probably will move bullet out 0.002 at a time to see when it hits the lands.

Erik
I'm getting consistent repeatable results now. As soon as I finish the above test mentioned above. I'll have that "warm fuzzy" about it.

 

[bozo699]

please skip this method unless you are in to imprecise loading or have a optical comparator to measure the length of the jam into the lands.

Firstshot,
Throw that old school stonypoint tool away and do this right. Take a case and set the shoulder back .002 or more and give the neck about .001 tension, start a bullet into the case a ways then put it in your rifle and close the bolt. That will give you your jam length, you will see the land marks in the bullet, take a measurement of the marks and run your seating die down to where you think they will just about disappear when you seat the bullet. take oooo steel wool and lightly clean the marks off and seat the bullet further and then rechamber the round and again look for land marks, if your eyes are old like mine you will need a Jewlers Loupe, there cheap! after repeating this several times you will see one land mark disappear , then another disappear until you don't see them any more, that is when your just at the lands, once you learn it is pretty fast and deadly accurate! Wayyyyyyy more then the hornaday or stoney point. If your competing you need to sort bullets base to Ogive and you will need to do this with your different lots of bullets you have sorted. If your just trying to get a so so accurate hunting load then do what you been doing.
Wayne.

Take note of the name of this forum,...".Accurateshooter" Yes I am into accurate loading and shooting and only could assume that everyone on here is the same, there are other forums out there for so so loading and shooting practices. The people shooting and winning at 1000 yards use the method I described! Don't bad mouth my method unless you have experience in it. Oh and I do have an optical comparitor at my disposal just for the record.
Wayne.

p.s actually two of them in our machine shop.

 

[dkhunt14]

I agree with you Bozo they should throw all them away. Once you learn what to look for with the steel wool and check it is so easy and repeatable. The very best thing about it is its FREE. Matt

 

[bozo699]

I agree with you Bozo they should throw all them away. Once you learn what to look for with the steel wool and check it is so easy and repeatable. The very best thing about it is its FREE. Matt

Spot on I also agree 100%
Wayne.

 

[bozo699]

the dia of the tool you use on your caliper is a different dia than your actual lands at the throat.
the diff dia means you are measuring up or down further on the bullet......

when you say sinclair is that the stony point type caliper tool or their hex nut comparator ?...

just a guess..but the dia of your lands at the throat and the dia of the tool appear to be different. Don't understand this statement

the word is ogive.... Yea... I know.. fat fingered that one

have you tried a sinclair/hornady comparitor ? I'm using a sinclair comparitor and the old version of the hornady OAL tool

Negative,.....most people I know build there own or use a chunk of there barrel they cut off prior to chambering. Then it is the same size when the barrel is new, one throat erosion starts you will be chasing the lands anyway
Wayne.

 

[stool]

except he does not have a pc of his bbl set up that way...
he HAS the stoney point type tool and yes it works...as he has shown.

and how do you chase the lands ACCURATELY. HOW DO YOU MEASURE how much JAM you have and where the lands actually start?
stoneypoint tool works..it is just a reference point but it is much better than an unmeasure, who knows how long, JAM.

the dia of the tool you use on your caliper is a different dia than your actual lands at the throat.
the diff dia means you are measuring up or down further on the bullet......

when you say sinclair is that the stony point type caliper tool or their hex nut comparator ?...

just a guess..but the dia of your lands at the throat and the dia of the tool appear to be different. Don't understand this statement

the word is ogive.... Yea... I know.. fat fingered that one

have you tried a sinclair/hornady comparitor ? I'm using a sinclair comparitor and the old version of the hornady OAL tool

Negative,.....most people I know build there own or use a chunk of there barrel they cut off prior to chambering. Then it is the same size when the barrel is new, one throat erosion starts you will be chasing the lands anyway
Wayne.

 

[GPat]

Wayne and Danny et al are correct, Danny has won a lot of matches so his advice should be regarded highly. All I could add to what they've prescribed is to do so with the firing pin out of the bolt.

I've recently simplified the way I determine seating depth on the recommendation of a friend. Start with the firing pin out, seat a bullet long in a fired and sized piece of unprimed brass, sized with your normal neck tension of .002" or so. Insert this dummy round into the chamber and close the bolt, if you can't close it, seat the bullet a little deeper (say .005") and try again, repeat if necessary but you should be able to get the bolt closed. Close the bolt, remove this round and measure it. Write this measurement down, pull the bullet and repeat two more times without resizing the case and using the same bullet. Usually the second and third time it's done are within a couple thousandths of each other and give you the most accurate readings. Use this measurement as your jam length. If you're comfortable with it, start there for your load development. Work off that measurement .003" at a time.

Right, wrong or indifferent. That's how I've been determining it for a little while now and I think it works.

If you insist on using a tool, I think the Sinclair is probably more repeatable, but when used properly won't give you jam length only the "touch".

 

[bozo699]

except he does not have a pc of his bbl set up that way...
he HAS the stoney point type tool and yes it works...as he has shown.

and how do you chase the lands ACCURATELY. HOW DO YOU MEASURE how much JAM you have and where the lands actually start?
stoneypoint tool works..it is just a reference point but it is much better than an unmeasure, who knows how long, JAM.

the dia of the tool you use on your caliper is a different dia than your actual lands at the throat.
the diff dia means you are measuring up or down further on the bullet......

when you say sinclair is that the stony point type caliper tool or their hex nut comparator ?...

just a guess..but the dia of your lands at the throat and the dia of the tool appear to be different. Don't understand this statement

the word is ogive.... Yea... I know.. fat fingered that one

have you tried a sinclair/hornady comparitor ? I'm using a sinclair comparitor and the old version of the hornady OAL tool

Negative,.....most people I know build there own or use a chunk of there barrel they cut off prior to chambering. Then it is the same size when the barrel is new, one throat erosion starts you will be chasing the lands anyway
Wayne.

Sir I do not wish to argue with you. I have used just about every way imaginable and The stony point/ Hornaday system works if you are precise about doing everything the same each and everytime, most people don't have that accurate of a touch. Now to answer your question, pour a cup of joe and sit back this will take a bit. You chase the lands with the method I mentioned also you can find hard jam that way and just touching, it is the purpose of the whole thing. NOW........I go one step further I use the optical comparator you mentioned to take an accurate measurement of my bullet, then I have one of my machinists build my seating stem to match the ogive of the bullet. I sort my bullets +or- .0005 . If and I repeat IF I can keep my neck tension perfect case to case I can repeatable keep my loaded round seating depth measured with very good equipment within about .001 or .0005 + or - and I can keep my total indicated runout to .001 or less also. I am able to keep my necks just about perfect with Gpat's near perfect neck turning tool. I have been able to do all this with a lot of years of trial and error, lots of mistakes, a lot of tutoring from some of the worlds best shooters right here on this forum. I didn't invent any of this I just listened to the people winning and copied them. I may have been one of the first to build my seating stems using a optical comparator but not many have one at there disposal. And I haven't seen total proven proof at 1000 yards that it even matters but it makes me feel better, thank you for your time.
Wayne.

 

[M14AMU]

Basically what these postings show is that what works for Joe may not work for Bill! ;D

 

[stool]

BINGO..we have another winner!!

Basically what these postings show is that what works for Joe may not work for Bill! ;D