Trouble finding the lands two different methods with wildly different results²

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mioduz

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Apr 22, 2009
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#1
I am trying to develop a load for my 6.5 cm

Using Eric cortina method from yt. I prepped a case and seated a projectile very long. Applied some lube and loaded it into chamber to find jam length
Results where 2.276 cbto

Using a hornady oal Guage and thr modified case I pushed as hard as I could on the springy thing to the point where the bullet what light embedded in barrel. Popped out projectile re inserted into case and measure
Results where 2.211


Those are wildly different. My only guess is that maybe in method one the bullet is stuck in the lands and is pulled out of the case slightly on extraction. Thoughts.???
 
#6
I use a case that has been fireformed to my chamber and make my own modified case for each rifle to use with the Hornady tool. Hornady will make you a modified case if you send them fireformed brass for not very much money, I think it's $15 but I only went that route once about 2 decades ago and figured I could just make my own. It's not difficult.
Then I use a "dirty" candle to soot up the bullet. Push the soot covered bullet into the lands very gently. You will see where the lands mark the soot on the bullet. You want to just barely disturb the soot. Maybe the first time you push in too hard and leave a "long" mark, so make a guesstimate of how much that is, back off the push-rod a hair, soot the bullet up again and repeat the process.
ETA: You can use a sharpie or a dry erase marker instead of a candle and soot with similar results. I use an Ottlight to look for markings on the soot or marker ink.
 
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#8
I would not jam it as hard as a can. Light pressure is all you need, and that will certainly cause the variation you are getting. You have to be consistent, and doing it as hard as you can won't get you accurate results.

You want to FIND the lands, not find the jam. I guarantee I can jam a bullet a lot harder into the lands with the bolt than you can with the Hornady spring pusher.
 
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#9
mioduz said:
I am trying to develop a load for my 6.5 cm

Using Eric cortina method from yt. I prepped a case and seated a projectile very long. Applied some lube and loaded it into chamber to find jam length
Results where 2.276 cbto

Using a hornady oal Guage and thr modified case I pushed as hard as I could on the springy thing to the point where the bullet what light embedded in barrel. Popped out projectile re inserted into case and measure
Results where 2.211


Those are wildly different. My only guess is that maybe in method one the bullet is stuck in the lands and is pulled out of the case slightly on extraction. Thoughts.???
Click to expand...

If you seat a bullet into a sized case and then use the camming action of the rifle to seat it deeper, what will happen is the bullet will be engraved and deformed by the leade. The degree of deformation is what you are seeing between the two methods you have already tried.

I use the slit case method. Even with that, the bullet gets stuck in the rifling do you have to use a cleaning rod to push it out instead of the bolt.

If you’re doing all of this to be within the magic .020” off the lands, then stop. It’s better to start load development at factory coal which is usually .040” to .060” off the lands. That’s a safe place to be given that bullets often vary more than .020” from lot to lot.
 
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#10
918v said:
If you seat a bullet into a sized case and then use the camming action of the rifle to seat it deeper, what will happen is the bullet will be engraved and deformed by the leade. The degree of deformation is what you are seeing between the two methods you have already tried.

I use the slit case method. Even with that, the bullet gets stuck in the rifling do you have to use a cleaning rod to push it out instead of the bolt.

If you’re doing all of this to be within the magic .020” off the lands, then stop. It’s better to start load development at factory coal which is usually .040” to .060” off the lands. That’s a safe place to be given that bullets often vary more than .020” from lot to lot.
Click to expand...
My intent was to start at .020 off the lands and work away from there with 3 shot groups until I found a stable node
 
#11
I use the Hornady tool and there is a bit of familiarization and practice needed to get a consistent feel for the bullet meeting the lands.

I take multiple measurements and when I get consistent results then I don't worry if I'm .005 off or so from an exact absolute measurement as this just becomes a bench mark for me when seating deeper and looking good grouping.

I'm not sure why I should care that much if its a super accurate absolute measurement. And, with some wear on the chamber I found myself limited on the long side by mag length.

Dunno....I'm not one of the highly experienced guys here so I may well be doing it wrong.
 
#12
918v said:
If you seat a bullet into a sized case and then use the camming action of the rifle to seat it deeper, what will happen is the bullet will be engraved and deformed by the leade. The degree of deformation is what you are seeing between the two methods you have already tried.

I use the slit case method. Even with that, the bullet gets stuck in the rifling do you have to use a cleaning rod to push it out instead of the bolt.

If you’re doing all of this to be within the magic .020” off the lands, then stop. It’s better to start load development at factory coal which is usually .040” to .060” off the lands. That’s a safe place to be given that bullets often vary more than .020” from lot to lot.
Click to expand...
Really? What kind are you using?
 
#15
When using the Hornady device push the bullet forward into the lands and then release your grip and measure. Because the plunger is plastic pushing hard will actually cause it to bow and give a false reading. Good video regarding this on the Ultimate Reloader site. Recommendation from Gordy Gritters, the accuracy guru.
 
#16
This is because Erik’s method finds what he calls “jam.” His definition of jam is the point where a bullet will be far enough into the lands you are in danger of sticking a bullet and it not extracting with the case in the event you need to extract a live round.

The reasoning behind this is he wants to have the most range for seating depth.

You likely won’t be able to push a bullet hard enough with the Hornady gauge to get it that far into the lands.
 
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#17
If you want to find “jam” = Erik’s method. Your seating depth testing will start with the bullet loaded into the lands though.

If you want to find the “touch” point = stripped bolt or Hornady tool (stripped bolt will generally be more consistent). If you use this method and back off X amount, you’ll usually be not touching lands when you start your seating depth test.


There are other methods, some mentioned here. Just realize different techniques measure different things. Use the one appropriate for you intended purpose.
 
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#19
mioduz said:
My only guess is that maybe in method one the bullet is stuck in the lands and is pulled out of the case slightly on extraction. Thoughts.???
Click to expand...

I think this is what happened to you.

When I fireform brass using jammed bullets I will find the "hard press" jam number with the hornady tool, seat out longer than that and try to chamber the round on a firm bolt close. I found that that much more than 15-20 thou past the hornady hard jam number starts to push the bullet into the case and if you extract the unfired round you end up with a result that is not much different than the Hornady number. Going 65 thou beyond the Hornady number will result in an extremely hard bolt close and seating the bullet deeper in the case.

I would try the Hornady hard jam number and back off 30 thou, or try the Wheeler method video above (age restricted, "How to find your lands exactly") and back off a bit from the "touch" point. I use both methods.
 
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#23
I use a dial depth gauge on the back of the barrel extension (Edit: on my DTA). It's super simple and very repeatable.

#1. Plop my fireformed reference brass into the chamber and zero out the depth gauge.

#2. Gently and carefully insert a long seated dummy round into the chamber and measure with the depth gauge.

#3. Subtract the depth gauge reading from your CBTO of the long seated dummy and there is your distance to the lands.

Once you have a piece of fireformed reference brass to establish a zero point it takes literally 30 seconds to calculate the distance to lands with ANY new projectile. It is extremely repeatable.

I pull my barrels to do a proper clean so I track throat erosion every cleaning session. You can even plot throat erosion against round count and establish a trend over the barrels life if you are into graphs and shit.

This method also works with traditional style barrels without an extension, but you will need a spacer for the depth gauge to work as the case head protrudes from the chamber.

You could even do this with the barrel still in the action, but finding a repeatable surface for the depth gauge might be difficult depending on how the rear of the action has been designed.
 
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#24
A good way to increase the repeatability of the Hornady tool is to completely remove the plastic rod and get all the flashing off of it. This should reduce the drag on the rod and make it easier to feel when the bullet hits the lands. Using this method you should never need to knock the bullet out of the barrel with a cleaning rod because you jammed it in there too hard. If it does stay in the barrel, a light bump to the stock should knock it free. If it doesn't, you pushed on it too hard.
I generally take 10 measurements; you can throw out your bad measurements and you should have all the rest within something like 0.003".
 
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#25
Depending on your chamber, your wildly different measurements suggested by the short measurement... you're likely touching the start of the freebore diameter, not the lands. Push the bullet past that point (wiggle it) and you'll feel it jump forward and stop again. That 2nd stop is the lands. 6.5 cm and a few other calibers have a small freebore diameter if you have a tightly cut chamber. The freebore diameter doesn't adequately account for the minor variations in bullet diameter.
 
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#26
BattleAxe said:
Depending on your chamber, your wildly different measurements suggested by the short measurement... you're likely touching the start of the freebore diameter, not the lands. Push the bullet past that point (wiggle it) and you'll feel it jump forward and stop again. That 2nd stop is the lands. 6.5 cm and a few other calibers have a small freebore diameter if you have a tightly cut chamber. The freebore diameter doesn't adequately account for the minor variations in bullet diameter.
Click to expand...
That bullet would have to be in there pretty damn crooked for your theory to work . I say no way in hell . More like eriks idiotic method stuck the bullet and pulled it .
 
#27
I measure mine with the barrel out of the action.

1. Hold the barrel horizontal, place the projectile in the chamber.

2. Slowly Rotate barrel to vertical so the projectile falls to the lands. Tap side of barrel to settle.

3. Measure from barrel face to back of bullet with depth mic. I take care to not jam the bullet any further when measuring.

4. Add Barrel face to bolt face distance to the above measurement.

5. Add projectile length to above measurement.

Now you have your OAL at light touch/gravity force.
 
#28
Haney said:
That bullet would have to be in there pretty damn crooked for your theory to work . I say no way in hell . More like eriks idiotic method stuck the bullet and pulled it .
Click to expand...
Not my theory. One of the top PRS gunsmiths in the country showed me in person how this happens with the SAAMI blueprint sitting on the bench. It doesn't have to be crooked. Normal bullet diameter runout variation can cause it in a tight chamber. Hornady 140s do it in mine. They shoot stellar but you can't use a light touch to find the lands.
 
#29
mioduz said:
I am trying to develop a load for my 6.5 cm

Using Eric cortina method from yt. I prepped a case and seated a projectile very long. Applied some lube and loaded it into chamber to find jam length
Results where 2.276 cbto

Using a hornady oal Guage and thr modified case I pushed as hard as I could on the springy thing to the point where the bullet what light embedded in barrel. Popped out projectile re inserted into case and measure
Results where 2.211


Those are wildly different. My only guess is that maybe in method one the bullet is stuck in the lands and is pulled out of the case slightly on extraction. Thoughts.???
Click to expand...
The 6.5CM bullet profile and lands I find other past methods did not work for me either. I used micrometer seater in a bump, try to chamber, change die and reseat, try to chamber and find when it chambers and measure, then because of multiple seatings on same bullet, I add .005 to last seated length and try another bullet and find usually about .002 thousands longer than the bullet first used. This has been very repeatable.
 
#30
Amazing how complicated some people make this.

Just measure from the muzzle to the bolt face. With gentle pressure, chamber a round that is loaded too long for the bolt to close. Measure from the muzzle to the bullet tip. The difference is your max OAL. Done.

It’s easier if you zero the first measurement (use a moveable stop on the cleaning rod).
 
#31
The Hornady tool is easily deformed. Do not over tighten the screw that locks the rod. Doing so leaves a more or less permanent dent that will affect where the rod licks in the future.
The bullet must only just touch the rifling. Best way I’ve found us to very lightly lube the ogive with sizing wax, hold the case in contact with the chamber, gently advance the bullet with the push rod. Stop when you just feel contact. Lock the rod. Pull the tool and take the measurement. Repeat 3 or more times until you get consistent readings.
If you still have inconsistencies try lubing the test case too.
In order to get a true number you must relate the measured dimension to the true value. Fired case is one way but prone to errors if CBTD is inconsistent or of your cases are actually headspacing off the extractor.
Using a stripped bolt will usually work best.
Another thing to understand is that every shit erodes the forcing cone. Research has shown that having large jump works best across barrel life. See Precision Rifle Blog for the story.
See my web site for techniques.
 
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#32
Yondering said:
Amazing how complicated some people make this.

Just measure from the muzzle to the bolt face. With gentle pressure, chamber a round that is loaded too long for the bolt to close. Measure from the muzzle to the bullet tip. The difference is your max OAL. Done.

It’s easier if you zero the first measurement (use a moveable stop on the cleaning rod).
Click to expand...

With what a 24" depth micrometer? Of all the ways to measure the lands, this is the most complicated.
 
#34
2aBaCa said:
With what a 24" depth micrometer? Of all the ways to measure the lands, this is the most complicated.
Click to expand...
No, with a cleaning rod with a locking collar, as I said at the end of my post. Set the collar against the muzzle to zero the bolt face position, then measure the gap with a bullet against the lands.

It’s not complicated at all, and a lot faster and more repeatable than the silliness some of you are doing. It shouldn’t be hard to understand either; if it is you’re overthinking it.
 
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#35
"generally take 10 measurements; you can throw out your bad measurements and you should have all the rest within something like 0.003"."

This is what I do also. Take 10 measurements, toss the obviously bad ones, then average the rest. Then I minus .005" and start load development at .005" increments.
 
#38
2aBaCa said:
Basically what @Yondering is doing. Still seems more complicated and more margin for error.
Click to expand...
Not really complicated at all. Takes less than a minute and requires no special equipment. It’ll take me longer to type this blurb then to use this method. Insert cleaning rod until it contacts the bolt face, mark rod, take bolt out and drop bullet into chamber, use pencil, primer tube, etc to push bullet into lands, push cleaning rod until it contacts tip of the bullet, mark cleaning rod again. Measure. Super easy. Very reproducible. Not cartridge dependent.
 
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#39
chase723 said:
Not really complicated at all. Takes less than a minute and requires no special equipment. It’ll take me longer to type this blurb then to use this method. Insert cleaning rod until it contacts the bolt face, mark rod, take bolt out and drop bullet into chamber, use pencil, primer tube, etc to push bullet into lands, push cleaning rod until it contacts tip of the bullet, mark cleaning rod again. Measure. Super easy. Very reproducible. Not cartridge dependent.
Click to expand...
And twice the time to use the Hornady guage.
You're having to use the rod and set collars twice, the second time with a another rod to push the bullet while simultaneously tightening collar. And getting a loose bullet into the chamber always goes well 🙄. You almost need 3 hands. Then measuring from the bullet tip and not the ogive?

I'm sure if you do it a bunch you can get it down but I'm sorry that's about the most complicated way to do it.
 
#40
You can use tape or an O ring or a sharpie. It doesn’t matter. It’s not complicated at all and doesn’t require 3 hands. To get the bullet into the chamber you literally just point the muzzle down and drop it in. But, I guess different people have different perspectives on what’s hard.

Even if you have a Hornady COAL gauge, if you have a new rifle in a different chambering and don’t have a case for it, or a tap to make one, then it’s useless. This technique is universally applicable, easy, accurate, and time efficient.
 
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#41
Yondering said:
Amazing how complicated some people make this.

Just measure from the muzzle to the bolt face. With gentle pressure, chamber a round that is loaded too long for the bolt to close. Measure from the muzzle to the bullet tip. The difference is your max OAL. Done.

It’s easier if you zero the first measurement (use a moveable stop on the cleaning rod).
Click to expand...

USE same. So easy and fast. I dont use any collars.

close bolt, put cleaning rod in till hits bolt face, mark rod at muzzle with sharpie. If you pull rod against edge of barrel you can get a very clean line to measure against.

Insert long round and slowly insert till hits lands. Mark rod again. Measure difference.

I put a rubber band on bolt to hold pressure while I mark rod second time. will be verry close and close enough to start load workup.

One thing, make sure bullet tip is not disformed AND put the end of cleaning rod that isnt cupped - ie male end down barrel


That or a stripped bolt and slowly seat bullet until bolt falls closed on its own.


GL
DT
 
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#42
I can actually see getting a reasonable measurement with the locking collars. The tape and marker stuff is a bit crude. Even scoring with a razor blade would only be a ballpark number.
 
#43
JBoomhauer said:
I can actually see getting a reasonable measurement with the locking collars. The tape and marker stuff is a bit crude. Even scoring with a razor blade would only be a ballpark number.
Click to expand...
They all index off the end of the barrel. I’d be willing to bet both the tape and Sharpie are as accurate as the collars. They’re probably accurate to within 5 thou. Plenty close for reloading. I’ve used this method on ~10 barrels with several different chamberings and several different bullets. Never unintentionally stuck one in the lands using the measurement as a basis.
 
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#44
chase723 said:
They all index off the end of the barrel. I’d be willing to bet both the tape and Sharpie are as accurate as the collars. They’re probably accurate to within 5 thou. Plenty close for reloading. I’ve used this method on ~10 barrels with several different chamberings and several different bullets. Never unintentionally stuck one in the lands using the measurement as a basis.
Click to expand...
I’m sure that is close enough, but I agree with the other comment that a locking collar is more accurate; it allows a direct solid measurement between the muzzle and the collar rather than eyeballing it to a mark. But unless you’re trying to load right at the lands (I don’t) it’s just a reference point.

FWIW for the collar I used one of those brass muzzle guides that fits over the cleaning rod (Shooter’s Choice? Whatever that common brand is with the yellow background) and flipped it over so the flat side is against the muzzle. I just drilled and tapped in from the side and inserted an 8-32 set screw with a piece of lead shot under it.

With the lead shot in there, I can leave the screw just tight enough so it’ll slide on the rod but stay in place where it’s set.

I also use a broken brass jag in the rod that I filed flat on the end, so it contacts the bullet tip consistently.

I think that adds up to less than $10 in special tools to measure lands this way, but IME it’s more consistent AND easier than any other method, including the Hornady tools or similar. It also is not affected by headspace of your brass, and doesn’t need a dummy cartridge like the Hornady tool. That’s a win-win in my book.
 
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#45
Rover31 said:
@Baron23
Take a fired case, new bullet
Lightly coat the bullet base “area” that will seat in the case neck insert bullet so it is long in the case, using care insert into chamber, close bolt, wait 10-15 min if done properly the bullet will be just at the lands.
Shown in this vid one of the methods

Click to expand...


I used this exact method from the UR video. Cross referenced using a hornady gauge. The measurement between the 2 was within. 002"

I used red loctite. Green would also work.
Apply it very sparingly!
Be sure absolutely none of it gets on the outside of the brass.
Don't put loctite on the bullet. Only inside the case neck.
 
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#46
2aBaCa said:
With what a 24" depth micrometer? Of all the ways to measure the lands, this is the most complicated.
Click to expand...
The stop collar will be set to the muzzle-bolt face length. With a round inserted to touch the lands the point of the bullet stops the rod so the collar is above the muzzle by COAL minus the amount the bullet point enters the cleaning rod female screw. So to get precise put something on the end of the rod that will accurately stop at the bullet tip. You can directly measure the distance with any caliper that takes inside dimensions greater than COAL.

This method takes the COAL. What you want (after bothering this much) is the distance from the case base to the ogive when the bullet is just touching the lands or CBTO.

Bullet manufacturing length runout is absorbed in the length between the ogive and tip. Sometimes quite a lot. It’s the reason we use the ogive as datum for precision loading.

I’m my experience the Hornady tool is sufficiently accurate and easy to get repeated readings that agree within a couple of thousandths.

The bolt lift method is I think the most precise method of obtaining the CBTO as an interior measurement.

In any event, if your resized cases are shorter than CBTD by more than 0.002 you may be headspacing off your extractor in reality when you fire.

It’s a bit tricky, and requires some thinking to get this measurement correct, and the apply it meaningfully. Particularly when we are learning that 0.040 -0.065 is a ‘good’ jump over barrel life for high accuracy. In other words don’t obsess over it unless you are a bench rest competitor …
 
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