Clarification on "distance from lands"

[PJ1]

Maybe my newbie status to reloading (<2years), but when you fellows refer to 0.xx" from the lands, I'm a little confused. Here's what I am presently doing to determine my distance from the lands:

I follow what Eric Cortina has done in one of his videos. I take a fired 6.5C case f.l. size and then mandrel the neck to give me 0.002" of neck tension. I then seat the bullet out to about 2.3" long(cbto) in the case, lube the ogive area, then chamber the dummy round. Jam comes out to be 2.293" and is very repeatable for Hornady 140g hpbt. Next I subtract 0.020" to give me 2.273" as my starting point. I have found that 2.270 to 2.267" from jam to be the sweet spot.

I have tried the o.a.l gauge method for touching the lands and I end up with varying results. Usually around 2.213" This ends up giving me lousy and non-repeatable groups.

So I am curious as to how you folks are doing this. Please forgive my ignorance.

 

[Ccrider]

Use the Wheeler method for finding the lands. Here is a link to a video. Alex did one as well but this is the first one I came across. Also, look at some of the old finding the lands threads.

One more thing, make sure your shoulder is pushed back far enough not to cause interference. With the pin removed, the bolt should fall freely with the piece of brass chambered.

https://www.facebook.com/video.php?v=236173297591911

 

[JEFFPPC]

Lots of confusing terms without concrete definitions. That is why I call it Touch. Seat a bullet in a dummy round, load it , pull it out and LOOK at it. All you need is a reference point to work from. Now you have one, go in, go out whatever. Your loaded rounds can be checked to verify each is correct to your developed load. Very simple but usually made hard by no common sense and over thinking, look at me I am smarter than the last guy. Don't make it harder than it is.

 

[RegionRat]

Not sure how you get from 2.270" - 2.268" and get all the way over to 2.213"

I followed the first part about how you found your jammed dimension to be 2.293" using a dummy round and then discovered your best groups around 2.270" - 2.268".

It sounded like you were doing okay and on track, so what did you do with the other method and why?

In most cases, it isn't difficult to get two different methods to more or less follow each other and to show why one method puts a little more or less force on the test bullet to cause a "slight offset" and repeatability issue between the two methods and even within any particular method.

That said, your delta between the two methods is way too big, so you are clearly having a problem but we need a more detailed description of what you are doing (mostly with what you called o.a.l gage) and observing to be able to debug you.

ETA: OAL can imply you are picking up on tip variations the are common in open tip match bullets, or it may mean something else. Also include the specifics on your observations and what you are using to measure and what you are touching on the bullet.

 

[MSS]

Videos | wheeleraccuracy

www.wheeleraccuracy.com

 

[6bra1k]

Maybe my newbie status to reloading (<2years), but when you fellows refer to 0.xx" from the lands, I'm a little confused. Here's what I am presently doing to determine my distance from the lands:

I follow what Eric Cortina has done in one of his videos. I take a fired 6.5C case f.l. size and then mandrel the neck to give me 0.002" of neck tension. I then seat the bullet out to about 2.3" long(cbto) in the case, lube the ogive area, then chamber the dummy round. Jam comes out to be 2.293" and is very repeatable for Hornady 140g hpbt. Next I subtract 0.020" to give me 2.273" as my starting point. I have found that 2.270 to 2.267" from jam to be the sweet spot.

I have tried the o.a.l gauge method for touching the lands and I end up with varying results. Usually around 2.213" This ends up giving me lousy and non-repeatable groups.

So I am curious as to how you folks are doing this. Please forgive my ignorance.

just to be clear..THIS IS NOT THE LANDS, NOR DISTANCE TO THE LANDS.
do more reading and try a couple methods.
you want a spot where if you make the cartridge .001 shorter, there are no longer 4 marks( 4 groove bbl)
that is TOUCH.

 

[Zero333]

Sometimes the distance to the lands and the JAM distance (where it actually sticks in the rifling) can vary by a lot.
I have a barrel shooting 80 gr Berger's, and the JAM distance is like 0.030" farther than the "touching the lands" distance. (going of off memory).

 

[Straightshooter1]

Maybe my newbie status to reloading (<2years), but when you fellows refer to 0.xx" from the lands, I'm a little confused. Here's what I am presently doing to determine my distance from the lands:

I follow what Eric Cortina has done in one of his videos. I take a fired 6.5C case f.l. size and then mandrel the neck to give me 0.002" of neck tension. I then seat the bullet out to about 2.3" long(cbto) in the case, lube the ogive area, then chamber the dummy round. Jam comes out to be 2.293" and is very repeatable for Hornady 140g hpbt. Next I subtract 0.020" to give me 2.273" as my starting point. I have found that 2.270 to 2.267" from jam to be the sweet spot.

I have tried the o.a.l gauge method for touching the lands and I end up with varying results. Usually around 2.213" This ends up giving me lousy and non-repeatable groups.

So I am curious as to how you folks are doing this. Please forgive my ignorance.

With .002" neck tension and jamming the dummy cartridge into the lands is giving you a lot longer measurement than if you're just touching. But I wouldn't expect there to be such a large difference like between the 2.293 you got with the hard jam and the 2.213 of touch with your OAL gauge. It doesn't sound right and I'd check to see if the uses of the OAL gauge is right.

When I use my Hornady OAL gauge, I have on a factory barrel found that the bullets would hang up a little and I needed to give it a little tap to get past that and actually touch the lands. I'm wondering if that kind of thing is happening with you . . .??? ¯\_(ツ)_/¯

 

[Ccrider]

just to be clear..THIS IS NOT THE LANDS, NOR DISTANCE TO THE LANDS.
do more reading and try a couple methods.
you want a spot where if you make the cartridge .001 shorter, there are no longer 4 marks( 4 groove bbl)
that is TOUCH.

Hell, I have trouble seeing those little marks, even with a magnifying glass. I can easily tell when by bolt falls down with no resistance.

 

[Rset]

What does it really matter? As long as you have a start point for reference, who cares if its +020 or -.140 or whatever. Find a start point, run your seating tests and go. Your rifle and your target will tell you what is best.

 

[JEFFPPC]

What does it really matter? As long as you have a start point for reference, who cares if its +020 or -.140 or whatever. Find a start point, run your seating tests and go. Your rifle and your target will tell you what is best.

Your absolutely correct. I doubt any one can distinguish a .001 mark as opposed to a .002 mark. Get a mark YOU can see. Go in go out , find a sweet spot. Once your die is set the mark is irrelevant anyhow. Sometimes I can't stand the .....oh well, some learn how and developer a process that works for them. Most never do.

 

[BULLET 05]

Use the Wheeler method for finding the lands. Here is a link to a video. Alex did one as well but this is the first one I came across. Also, look at some of the old finding the lands threads.

One more thing, make sure your shoulder is pushed back far enough not to cause interference. With the pin removed, the bolt should fall freely with the piece of brass chambered.

https://www.facebook.com/video.php?v=236173297591911

Will this work with a savage action.

 

[hpshooter]

Will this work with a savage action.

Yes, if you put a wrap of tape around the bolt to hold the retaining pin for the bolt head in place.

 

[D-4297]

Guess I'm the odd-ball here . I use the Hornady gauge , and have no trouble with using it . And I take my measurement from the Ogive of the bullet "TOUCHING" the LEADE . NOT the Lands . If you're touching the Lands ,, you're JAMMING the bullet . Not a good way to get a accurate , or consistent reference measurement in my mind . I do ten measurements , write them down and take the average . Then do seating tests from there . Touch and feel . Not for the Ham-handed.

 

[Ned Ludd]

How does one know exactly how deep a bullet is jammed into the lands without making inferences via other measurements? All bullets are not the same and everyone's technique for doing this may differ a bit as to what constitutes a "hard" jam. When using that approach and you start moving the bullet back out of the lands during a seating depth test, you are merely guessing as to where the bullet is just barely touching the lands. In using approaches designed to find "touching", the risk is the opposite. That is, you may think the bullet is just just barely kissing the lands, when in reality it could be .003" to .005" or more into the lands.

Regardless of which approach you employ, you are merely establishing a reference point that may or may not be accurate with respect to the distance you think it is in relation to just "touching" the lands. Nonetheless, as a reference point, we use it as though it were accurate in order to set up a seating depth test. Then we let the [very] accurate CBTO measurements taken from the actual loaded rounds of a seating depth test and the subsequent groups on the target tell us exactly what CBTO measurement constitutes optimal seating depth, which is easily reproducible.

 

[6bra1k]

Guess I'm the odd-ball here . I use the Hornady gauge , and have no trouble with using it . And I take my measurement from the Ogive of the bullet "TOUCHING" the LEADE . NOT the Lands . If you're touching the Lands ,, you're JAMMING the bullet . Not a good way to get a accurate , or consistent reference measurement in my mind . I do ten measurements , write them down and take the average . Then do seating tests from there . Touch and feel . Not for the Ham-handed.

NOT, actually lots of "not's" in this post

 

[PJ1]

Not sure how you get from 2.270" - 2.268" and get all the way over to 2.213"

I followed the first part about how you found your jammed dimension to be 2.293" using a dummy round and then discovered your best groups around 2.270" - 2.268".

It sounded like you were doing okay and on track, so what did you do with the other method and why?

In most cases, it isn't difficult to get two different methods to more or less follow each other and to show why one method puts a little more or less force on the test bullet to cause a "slight offset" and repeatability issue between the two methods and even within any particular method.

That said, your delta between the two methods is way too big, so you are clearly having a problem but we need a more detailed description of what you are doing (mostly with what you called o.a.l gage) and observing to be able to debug you.

ETA: OAL can imply you are picking up on tip variations the are common in open tip match bullets, or it may mean something else. Also include the specifics on your observations and what you are using to measure and what you are touching on the bullet.

Thanks to all for the replies.

The hornady oal is what I have been using and it just lead to a lot of frustration for me. If it works for others, great. What I found, and was noted by Straightshooter 1, is that I had to add additional pressure on the piano wire once I could feel the initial touch of the bullet. Seems strange to have to apply more pressure once you feel the initial touch and I did take measurements of the two. The seating , in my opinion, was inconsistent and this led to the rather large differences in readings. None came close to 2.270" cbto using Eric's method with jamming and subtracting 0.020" to start out with.


The point of my question was to see what methods you guys were using as I know that rifle lands will gradually slope to reach the full caliber of the bullet. I have followed one of your suggestions by taking one of my live rounds and chambering it. That round measured 2.270" cbto before chambering it. After chambering, I had the same 2.270"cbto with very light marks from the lands on opposite sides, so it maybe best to drop down to 2.268" and see how they perform. I have been achieving 0.50 moa at 100 yds, but the es and sd numbers are in the 30's and that concerns me.

Feel free to correct me on anything you think I'm screwing up.

 

[tsyarnall]

As far as getting your reloads to a repeatable measurement and then, adjusting from there for best seating depth of your bullet, IMO, the Wheeler method is hard to beat. Pick one that you prefer ( Wheeler or Hornady tool) and stick with it. The problem is so many different names/terminology for the same point or measurement and differing ways of getting to the same place can really, really get confusing. At least for me.

 

[miningshawn]

I fought this battle for my first year or so as well, and it can be confusing.

Using the same equipment as you, (presumably), a Hornady OAL gauge and and a Hornady Bullet Comparator, I have developed the following method.

Using a Hornady Modified Case I insert the bullet of choice and push firmly. After locking I use the bullet comparator to find distance to ogive. BTW all measurements are taken from the ogive in my world - I learned that distance to tip is far too variable. I will perform the measurement as many as 10 but never less than 5 times. I average the result and that becomes my new "zero" distance for that bullet in that rifle. I will record that measurement and until a new bullet development comes along that will remain my "zero" for that rifle using that bullet.

Now that that is established I will start seating deeper in increments of .005" and shooting groups of 5 to determine optimum seating depth. The "sweet spot" for me in .264 with heavy-for-caliber (above 130gr) bullets tends to be about 0.20" to 0.30" and again around .050" to .060". Because components are getting so hard to find I will often start at .020" and/or .050" of jump and work in from there instead of running a full series from the lands.

You didn't mention if you are shooting from a magazine. If you are, the "zero" distance is the magazine - often 2.880" OAL, and measuring the ogive distance from there. That being the longest distance you can load and still use the magazine - it makes no difference the distance to the lands. Now the tuning window for seating depth begins with the magazine maximum OAL.

As the lands erode there may be very small changes to optimal seating depth, (my experience has been that as the lands erode it may be necessary to adjust outwards to "chase" the lands).

Once I started working from a "zero", all of my problems pretty much dried up. The best advice came from folks on this forum and from the Berger Tech line. Walt is gone, but Phil and Cory are still giving great advice.

Good luck!
Edited 2.280" to 2.880". Max mag length for a typical AICS mag.

 

[Ned Ludd]

Because you already have the Hornady OAL gauge, one thing you can do is to practice with it until you can obtain the same measurement repeatedly with a single bullet. It takes a bit to get the "feel" for using it, and by using the same bullet over and over, you should eventually be able to obtain reproducible measurements with it. I hold the end of the outer sleeve tight to push the case tight into the chamber. I hold it on and just above the set screw collar with my left hand thumb and first two fingers, then push gently on the plastic stick with my right hand until I feel a very slight "touch". At that point, I use the left hand ring and pinky finders to hold the plastic pushrod still with the bullet touching the lands, then tighten the set screw with my right hand. I use a cleaning rod from the muzzle to push the entire bullet/OAL gauge assembly back out fo the chamber to take measurements. There are a variety of different ways to achieve the same goal, but practice with a single bullet can help with achieving consistency in the measurements.