The lands

[NCHillbilly]

I’m not the one advocating he jam anything, that was someone else. I have been telling OP to measure to touch, not to the point where he pulls a bullet...

Think about this for a second.
If you don’t know the measurement to touching the lands how do you know that for a given CBTO seating depth (+- your regular variance) wont have some bullets jumping, some touching and some jamming?

What happens when you are on the verge of pressure with a heavy powder charge, decide to load a little longer and end up unknowingly into jam?

What happens when you need to load some more ammo and have different brass, neck preparation process, lubing (or not) projectiles etc etc etc and you lose your “master” dummy loaded round seated to jam? Your new jam number will be different to the original and you have no point of reference from before.

By measuring to touch you have a REPEATABLE point of reference that wont change regardless of your brass prep or other variables.

You could argue that a smart move would be to write this all this info down in the first place, but a smart person wouldn’t use “jam” as a reference point either.

I may be the one you're talking about, but I'm not telling anyone to jam, unless they know what they're doing. I only do it at the begining of load development to find my charge ceiling. Once I start seeing pressure, I'll back off .5 grains and use that as my max charge. It's all in the stickies posted at the top of the sub-forum. I certainly would NOT jam, unless I had worked up, and yes, I know where my lands start, so I know when I'm .010" into the lands. Sorry if I caused any confusion.

 

[Shootin Stuff]

I may be the one you're talking about, but I'm not telling anyone to jam, unless they know what they're doing. I only do it at the begining of load development to find my charge ceiling. Once I start seeing pressure, I'll back off .5 grains and use that as my max charge. It's all in the stickies posted at the top of the sub-forum. I certainly would NOT jam, unless I had worked up, and yes, I know where my lands start, so I know when I'm .010" into the lands. Sorry if I caused any confusion.

Nah man you’re making sense. I read your comments as you found your CBTO to touch and loaded +0.010 for a pressure test only, once you found pressure at that depth you came back to a -x.xxx value and continued your load development from there.

This is all about the @hollywood1981 circus and how the lands don’t matter to him, as he goes on to say he mashes a projectile into the very thing that doesn’t matter to him...

 

[hollywood1981]

Nah man you’re making sense. I read your comments as you found your CBTO to touch and loaded +0.010 for a pressure test only, once you found pressure at that depth you came back to a -x.xxx value and continued your load development from there.

This is all about the @hollywood1981 circus and how the lands don’t matter to him, as he goes on to say he mashes a projectile into the very thing that doesn’t matter to him...

OMG you are still talking about this subject I mean seriously there are more than one way to skin a cat. Once again the lands of the rifleling does not matter to me and where it is. Once I again I do not mash the projectile into my rifling. Your a dip shit if you think I do that for real. Just rewatch the video AGAIN that I posted. I do the same thing as Erik Cortina does. So stop the speculating on what I do shootinstuff, because you obviously in this aspect have no clue what you are talking about. Once again jam and lands are two different measurements and reference points.

 

[Shootin Stuff]

OMG you are still talking about this subject I mean seriously there are more than one way to skin a cat. Once again the lands of the rifleling does not matter to me and where it is. Once I again I do not mash the projectile into my rifling. Your a dip shit if you think I do that for real. Just rewatch the video AGAIN that I posted. I do the same thing as Erik Cortina does. So stop the speculating on what I do shootinstuff, because you obviously in this aspect have no clue what you are talking about. Once again jam and lands are two different measurements and reference points.

@Dthomas3523 dragged this back from the dead not me, but since it IS back then please explain what you are jamming into if not the lands?

 

[hollywood1981]

@Dthomas3523 dragged this back from the dead not me, but since it IS back then please explain what you are jamming into if not the lands?

No you dragged this back from the dead mentioning my forum name in your stupid comment. You are nothing but a troll at this point. I really do not have the time to debate with you AGAIN! Correct me if I'm wrong, in this thread you where proved wrong. Again I'm not here to start shit, but when you bring up my name in a subject that has been long gone, you are indeed stirring the pot with your nonsense ideology. Once again, please do your research and homework. I'm not debating if touching the lands or jamming the lands is wrong or right when finding your reference point on load development. You can do it both ways, but where you are wrong is jam and touching the lands is 2 diffrent things PERIOD! I'm just going to be the bigger person, and put this to rest once and for all. You do it your way, I will do it mine. Both ways are technically right i give you that, for finding a reference measurement for a load up. Do some more homework and reloading, and go shoot that is what this is all about. It's suppose to be fun, and about helping ppl on here become better. So please stop your nonsense, and move the on!

 

[Dthomas3523]

@Dthomas3523 dragged this back from the dead not me, but since it IS back then please explain what you are jamming into if not the lands?

Just doing my job making sure bad info is called out or purged. You know enough to lead someone unknowingly down the wrong path.

 

[Shootin Stuff]

Ok, I’m done with this.

To any potential future readers:
If you load your dummy to the point of touch and zero your calipers, you have a reference point that is neither jammed nor jumped, but a true zero (or as close as practical/possible).

Any positive number after zeroing is an amount of jam (however small it may be) and any negative number is an amount of jump.

It really is that simple.

 

[Benjo]

Hey I’m new to reloading,but done lots of research and now have my (jam and kissing) measurement
sorry couldn’t help myself. But where would you start 10 thousand 20 thousand back?

 

[Benjo]

10 thou

Thanks would I likely see a massive difference at 20 tho?

 

[Benjo]

Define massive

I mean in relation to moa, would 10 tho difference increase moa dramatically ? I.e if you where getting .5 moa @ 100yrds
and then seated bullets another 10 tho back would groups open up .5 or 1 moa etc ?

 

[Tokay444]

Load a round to max mag length. Does it chamber and extract without drag on the bolt? Yes? Then that’s your max length and start seating deeper from there.

 

[308pirate]

No shit lol, I'm not debating that. Obviously you have to go thru the barrell where the bullet loads into you chamber to find either or. All im saying is I use the jam method to get initial measurement, I don't use the kissing the lands method. I take my jam measurement and adjust my seating depth back from there.

You do whatever you want, but without knowing where your datum (the start of the lands) is, your method give you no idea if the ogive of your bullet is right at the start of the lands, or .020" past them.

I strongly encourage any noobs reading this to ignore your advice.

 

[308pirate]

This is incorrect.

There’s finding a touch point (some call kissing, or other names) and then there is jamming which is loading into the lands and further than your touch point.

When you jam or load into lands, there is a possibility of sticking/pulling a bullet. Things like neck tension will dictate how far jammed or loaded into the lands will pull the bullet.

Finding and loading to your touch point will not stick a bullet (unless large amounts of carbon buildup which creates a jam situation).

@Shootin Stuff is 100% correct.

 

[Deleted member 113831]

Mr. Cortina's method is concerned with only 2 things:
1) Not sticking a bullet in the rifling and having it pull out to be left in the barrel.
2) Establishing a baseline to seat deeper than.

The initial amount of additional seating depth is more than enough account for any difference between "touch" and "jam".

Furthermore, he makes the point that seating from "touch" isn't as consistent as people think, because the very angle of the lead changes as the throat wears. So for accuracy concerns, chasing the lands using "touch" will vary as much as any other method.

However, if you are only concerned with safety, then your "jam" measurement minus (wtf ever...0.010", 0.020"...) will always be relevant.

 

[upsdownsideways]

Load a round to max mag length. Does it chamber and extract without drag on the bolt? Yes? Then that’s your max length and start seating deeper from there.

Simple and concise.

 

[chadrp]

Is it necessary to remove the plunger ejector if just finding jam like Cortina method? It didn't look like he did but I didn't know if his action had a mechanical or plunger ejector.

 

[MakeSawdust]

Is it necessary to remove the plunger ejector if just finding jam like Cortina method? It didn't look like he did but I didn't know if his action had a mechanical or plunger ejector.

It is not necessary. You will have improved feel if you want to feel the bullet in the lands or not. The Cortina method only seeks to find a soft enough jam that the bullet will not pull out of the case when extracting a loaded round.

A word of caution. Mr. Cortina is very consistent with neck tension, annealing, etc. If you want to be lazy (I am) and not anneal or only anneal every 3 firings then your neck tension will vary some. A jam depth that didn't stick a bullet could start to stick a bullet after a few firings. For this reason, I use the Wheeler method or the Mark Gordon method to find the point where I am touching the lands. From there I determine where I start my jump.

Other than that, I do the same thing as Mr. Cortina. I tried chasing the lands for a couple barrels. It was a disaster. It works best for me to shoot the load until it goes out of tune. At that point I either tune the load via seating depth, or if things have slowed down significantly, I will add powder to get the speed back, shoot a ladder at distance, and then tune the middle of the node with seating depth in .003" increments. Once I have the gun shooting good again, I run that same load until it will no longer shoot.

When I chased the lands, I was having .006+ per hundred rounds of throat erosion. I would change seating depth to chase it. Eventually my load would slow down or shoot poorly. Then I would have to do a complete new load workup. I got crunched for time once and had some left overs. They were jumping about .075" or more (I was chasing the lands at .010" off). I tried them. Back to good groups and nearly the same speed as when I started. That proved to me that chasing the lands is an effort in futility. Find the seating depth node and shoot until something is wrong. At that point it makes sense to change things up and see if the barrel will shoot or if it is dead.

 

[chadrp]

It is not necessary. You will have improved feel if you want to feel the bullet in the lands or not. The Cortina method only seeks to find a soft enough jam that the bullet will not pull out of the case when extracting a loaded round.

A word of caution. Mr. Cortina is very consistent with neck tension, annealing, etc. If you want to be lazy (I am) and not anneal or only anneal every 3 firings then your neck tension will vary some. A jam depth that didn't stick a bullet could start to stick a bullet after a few firings. For this reason, I use the Wheeler method or the Mark Gordon method to find the point where I am touching the lands. From there I determine where I start my jump.

Other than that, I do the same thing as Mr. Cortina. I tried chasing the lands for a couple barrels. It was a disaster. It works best for me to shoot the load until it goes out of tune. At that point I either tune the load via seating depth, or if things have slowed down significantly, I will add powder to get the speed back, shoot a ladder at distance, and then tune the middle of the node with seating depth in .003" increments. Once I have the gun shooting good again, I run that same load until it will no longer shoot.

When I chased the lands, I was having .006+ per hundred rounds of throat erosion. I would change seating depth to chase it. Eventually my load would slow down or shoot poorly. Then I would have to do a complete new load workup. I got crunched for time once and had some left overs. They were jumping about .075" or more (I was chasing the lands at .010" off). I tried them. Back to good groups and nearly the same speed as when I started. That proved to me that chasing the lands is an effort in futility. Find the seating depth node and shoot until something is wrong. At that point it makes sense to change things up and see if the barrel will shoot or if it is dead.

Thank you, thats some good info!

I do not have an annealer so i dont anneal yet. Ive only been shooting 140eldm so far and used wheeler method to find the lands and have been shooting them at .090 off that with good results.

I want to try some 130 and 140 burgers so I pulled my ejector so I could do both Cortina and wheeler methods just to compare. I normally mandrel with a .002 under but used a .001 under just to be a little more cautious using Cortina's method. What i found was kind of interesting.

I dont have the exact numbers in front of me so going off what I recall which is close.

The Berger 140 hybrids had .040 difference between the cortina jam and the wheeler touch measurement.

The Berger 130 are hybrid had a .115 difference between jam and wheeler touch measurement.

I would assume the difference is explained in the bullet profile with the 140 being more pointy and the 130 more rounded??

Edited to add both were checked multiple times with very similar results