Bullet seating into the lands.

[dbduff]

Finding where your lands are is relatively easy provided you have the tools to strip your bolt.
The Sinclair & Hornady tools push the bullet being tested into the lands just enough to throw off the readings.

Wheeler Accuracy has posted a very nice video:

super good information.

 

[carlsbad]

I don't think I'll ever be able to measure up to Mr Smith's intellectual standards so I'm gonna go cry in my Partial Differential Equations book. --Jerry

 

[carlsbad]

"Mom, can you bring my dinner down to the basement? I'm in an important argument on the internet."

 

[Mark W]

"Mom, can you bring my dinner down to the basement? I'm in an important argument on the internet."

I always liked this one....

 

[Shooter13]

The copper jacket is malleable, therefore there will be a certain jam distance that does not seat the bullet deeper when the round is chambered.

And with all that being said don't try to extract it if you are jamming into lands.

 

[David Christian]

Why don’t we all go find the closest range or desolate field and blow off a few rounds. Sure seems like this quarantine things is getting to all of us, including me!

 

[Straightshooter1]

Why don’t we all go find the closest range or desolate field and blow off a few rounds. Sure seems like this quarantine things is getting to all of us, including me!

Let's go . . .

 

[Intheshop]

This pic doesn't give the whole story because I never could get a good shot of how each land was so perfectly aligned,length and position wise. This is a 2016/17'ish R700 223 brand new factory barrel ,Lee 225-55. 18.8g of H4198=tiny groups. This is one of my favorite pics. Hope this helps on a visual of how the lands to ogive is a complex interface. I sort of understand it,but the math gets a little over my pay grade. I've "coped" enough crown (mould),not to mention metal tubing to fill several tandem axle dump trucks. So,never bothered with the math... it's either "fitted",or it's not.

The luxury in cast is we can change the bullet at a whim. 2nd and 3rd pics are of a taper bump die that,I can't remember the reamer's angle? Anyway,the beauty of this taper is that it can be manipulated,on the axis... independent of the base location. Like math,and metrology,it's easier to see than measure sometimes.

 

[Intheshop]

This is a 7mm BTW

 

[Chuckhunter]

Call it like I see it ! Freeloader sucking the life out of the place ....that's OK with you ? Seems pretty soft.

Daleboy, they have this sweet little button called ignore, I pushed it on this clown long ago.

 

[Ccrider]

It'll move if you jam it a quarter inch. I run very light neck tension (.001") and .020 jam and they don't move. Most people run more neck tension than I do and nobody that I know jambs much beyond .040.

So sure you can move it if you try. But what will happen more likely is you jam it, it doesn't move but bullet gets stuck in the lands. You have to pull hard to open bolt, extracting bullet and dropping powder in the action....why a lot of people don't like to jam.

--Jerry

Pretty much gone full circle. What is jam? All I need is a consistent starting point. You can get that by loading long and then pushing into the lands with your bolt. Or, strip your bolt if you are able to do so.

 

[std7mag]

So, essentially when i take a fired case and size the neck just enough to hold the bullet, insert into rifle, close bolt, carefully remove & measure. Then take 0.005" off that distance, i'm actually jamming the bullet?

Berger VLD-H.

This gives me my best groups from my hunting rifles.

 

[JEFFPPC]

I think there is a misunderstanding in that some view jammed as actually pushing the bullet into the case while others view it as touch or a visual mark from the rifling. I use the term touch since that is what I want to know. At what point does the ogive engage the lands. I think the idea that if your touching the lands your automatically pushing the bullet deeper in the case is not valid. Depending on many factors it may or may not be true. I prefer to use the method as described by Dale early in this post. If you feel your always driving the bullet deeper in the case why adjust seating depth? It will always be the same.

 

[JEFFPPC]

So, essentially when i take a fired case and size the neck just enough to hold the bullet, insert into rifle, close bolt, carefully remove & measure. Then take 0.005" off that distance, i'm actually jamming the bullet?

Berger VLD-H.

This gives me my best groups from my hunting rifles.

If that is the point of best accuracy how you measure is a mute point. Your target has told you.

 

[justpassinthru]

I've been using this for measurements taken at the ogive.
https://www.whiddengunworks.com/product/multi-purpose-overall-length-gauge-2/
By using the bushing that matches the lands in your barrel, you get one number that works with all bullets. It makes no sense to me for a company to make a measuring tool that touches the bullet so far away from where the lands of the rifling meet it. I bought the Hornady system but returned it.

 

[mike mccormick]

Answer me one thing: Is the world round or flat?

Spherical, actually.....

 

[KY_Windage]

I do not see why there is any advantage to having your bushing touch where your lands touch. I just need repeatability. I get that just fine with the Hornady system.

 

[KY_Windage]

So, essentially when i take a fired case and size the neck just enough to hold the bullet, insert into rifle, close bolt, carefully remove & measure. Then take 0.005" off that distance, i'm actually jamming the bullet?

Berger VLD-H.

This gives me my best groups from my hunting rifles.

No, if you added 0.005" to your measurement you would be jamming.

 

[Richard Coody]

Wow all this over a simple datum point to start seating test from. Doesn't matter what it is as long as it is repeatable. Whatever works for you!

I use the stoney point and tap the rod to what I call a hard jam. Don't believe I could put enough neck tension on a case to pass this point. I find it repeatable and from there I only can go one direction.

I could care less what someone else defines as touch. With a custom action put together by at top Smith that drop of the bolt is a beautiful thing but in the real world lots of actions aren't that smooth. If the barrel has a few tool marks in the throat that could easily make one believe that was touch. My thought after barrel break in there is a good chance touch has moved.

 

[justpassinthru]

I do not see why there is any advantage to having your bushing touch where your lands touch. I just need repeatability. I get that just fine with the Hornady system.

If it doesn't, every time you use a bullet with a different ogive profile, you have to start again from square one. With the Hornady system, do you not have to take a measurement for each bullet used and they're all different?
If I'm going to measure something relative to the lands, I want to do it right there, not farther down on the bullet.
That's the way I see it anyway, may be totally wrong.