Finding the Lands

[One Hole]

Lots of methods for finding the lands but can someone explain a simpler or more accurate method then just taking a new or a fired and neck sized unprimed case seating the bullet long, chambering it then carefully pressing it out from the muzzle with a cleaning rod? Then using this dummy round to setup seating die.

 

[charlie 7]

Lots of methods for finding the lands but can someone explain a simpler or more accurate method then just taking a new or a fired and neck sized unprimed case seating the bullet long, chambering it then carefully pressing it out from the muzzle with a cleaning rod? Then using this dummy round to setup seating die.

Drop the projectile in the chamber.

Use the RCBS mic appropriate for your chambering.
Unscrew the steel projectile, put it aside and extend the nylon insert.
You may use the hex key to make the nylon slide in with little resistance.
Drop it in the chamber (remember you have the projectile there too).
Close the bolt.
Open the bolt and extract the RCBS mic making sure you do not extend or shorten the nylon insert.
Put the extracted RCBS mic in the base holder, push the projectile out of the land – use a cleaning rod.
Place the projectile on top of the RCBS mic and delicately screw in the
ogive top, to the contact point.
Take a reading. Voila, you have the base to the land measurement.

 

[WapitiBob]

Do you want "touch" or "jamb"?
You can smoke a seated bullet (wax candle soot) and will see when it "touches" or use the Hornady gage with light pressure. I see .003" difference between those two methods. Heavy pressure on the Hornady gage or using the lands to push the bullet back into the case will increase the measurement by quite a bit; I saw over .010" increased length with those methods. All on a new 7PRC and 195 EOL.

 

[One Hole]

Do you want "touch" or "jamb"?
You can smoke a seated bullet (wax candle soot) and will see when it "touches" or use the Hornady gage with light pressure. I see .003" difference between those two methods. Heavy pressure on the Hornady gage or using the lands to push the bullet back into the case will increase the measurement by quite a bit; I saw over .010" increased length with those methods. All on a new 7PRC and 195 EOL.

Interesting. I guess it's really all relative. I just don't want to be close to touching during pressure testing. How much jump do you start with?

 

[med358-boise]

I solved this by not worrying where the lands are exactly. Rarely do we as hunters load to the lands. So I simply, close the bolt insert a cleaning rod with a flat jag on it and mark it with a piece of tape at the muzzle. Then I repeat this with a bullet seated against the lands and repeat the process and tape the rod again at the muzzle. I now measure the two leading edges of the tape and I have a very good estimate of the max COAL for that bullet.

But bullet length is the most variable dimension on a bulIet. So, now I measure the "CBTO" of that cartridge and subtract 10/1000 for regular bullets or 60/1000 for Barnes. I now have my starting "CBTO" for load development.

Eric Cortina does a good job of explaining the philosophy here.

 

[jseandsje]

With my mill, I perfectly split the neck of a case to .05 into the shoulder on both sides. Then run through resizing die.

Put a bullet slightly in mouth and slowly close bolt. Do this 5 times. Usually all 5 measurements are within .001 of one another.

No need to remove ejector or extractor. Have tested and there's never more than .002 difference.

For hunting rounds, set back .015 for C&C, .050 for mono's, to start.

Even if this is not exact, gives point of reference for consistency.

Our 8 big game rifles, using this method, are trustworthy well beyond our imposed limits.

 

[Varmint Hunter]

Lots of methods for finding the lands but can someone explain a simpler or more accurate method then just taking a new or a fired and neck sized unprimed case seating the bullet long, chambering it then carefully pressing it out from the muzzle with a cleaning rod? Then using this dummy round to setup seating die.

This inexpensive tool will get you there with much greater accuracy then the method you've described.

Lock‑N‑Load® O.A.L. Gauges & Modified Cases - Hornady Manufacturing, Inc

Lock-N-Load® O.A.L. Gauges Regulating seating depth and the resulting jump to the rifling is widely regarded as fundamental to improved accuracy. A few thousandths of an inch change between the bullet and the rifling can make the difference betw...

www.hornady.com

 

[Phil Rizzo]

I've run 4 ladder tests and multiple groups in a new rifle this weekend, firing brass for the first time and getting 100-125 shots down the hole. Using up supplies I've had for a while.
140 Nosler BT
150 Nosler BT
147 Apex Afterburners
168 Nosler ABLR.

Each of these 4 shot outstanding groups at touching to .005 of the lands with powder charges 2-3 grains wide…careful backing off too much automatically.
Don't be afraid to get close if needed. I've been shooting bullets seated there since my dad loaded for me as a pre-teen with no problems. Touching isn't jammed!

 

[Coyote Shadow Tracker]

Lots of methods for finding the lands but can someone explain a simpler or more accurate method then just taking a new or a fired and neck sized unprimed case seating the bullet long, chambering it then carefully pressing it out from the muzzle with a cleaning rod? Then using this dummy round to setup seating die.

LOL Modified Case.

 

[WapitiBob]

Interesting. I guess it's really all relative. I just don't want to be close to touching during pressure testing. How much jump do you start with?

I use 20

 

[Coyote Shadow Tracker]

This inexpensive tool will get you there with much greater accuracy then the method you've described.

Lock‑N‑Load® O.A.L. Gauges & Modified Cases - Hornady Manufacturing, Inc

Lock-N-Load® O.A.L. Gauges Regulating seating depth and the resulting jump to the rifling is widely regarded as fundamental to improved accuracy. A few thousandths of an inch change between the bullet and the rifling can make the difference betw...

www.hornady.com

We have Drilled & Tapped hundreds of Modified Cases for well over 200++ shooters the past few years. We have a number of cases that have to send out to a LRH members tomorrow. Not going to tell anyone how to measure your barrel's Freebore to the Lands, but a lot of reloaders use this method. Colton will get your Cases out tomorrow. Had some medical setbacks from last week.

 

[jseandsje]

This inexpensive tool will get you there with much greater accuracy then the method you've described.

Lock‑N‑Load® O.A.L. Gauges & Modified Cases - Hornady Manufacturing, Inc

Lock-N-Load® O.A.L. Gauges Regulating seating depth and the resulting jump to the rifling is widely regarded as fundamental to improved accuracy. A few thousandths of an inch change between the bullet and the rifling can make the difference betw...

www.hornady.com

Modified cases must be bought, or you can make your own, for each different cartridge.

 

[Phil Rizzo]

9/32" drill bit
5/16-36tpi tap

 

[MagnumManiac]

I use the split case method.
Cut 2 slits opposite each other in the neck, remove the burrs, size the neck, seat a bullet long and CAREFULLY chamber it SEVERAL times while measuring either BTO or COL and then CAREFULLY extract the case.
I normally disassemble my bolts doing this and remove the ejector plunger if there is one.
Once you get the feel for this, it is very accurate and repeatable with the easiest method I have found.
I have the Sinclair tool, the RCBS and this is more accurate than any of them.

Cheers.