Measuring for Lands

L

Lance B

Sergeant
Full Member
Minuteman
Mar 13, 2008
142
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NJ
#1
I am trying to measure for the lands of my rifle. When I insert a dummy round , I get "what looks to be 4 or 5 dirt marks around the bullet, is this the lands contacting the round? And if I want to be .010 from the lands do I use this mark as a reference.
Thanks, Lance

 
#2
Re: Measuring for Lands

I'd like some clarification too . . .

My current procedure is to slowly increase OAL until five symmetrical marks can be seen around the ogive of a dummy round with a bullet that has been dipped in blue die maker's ink and then chambered.

I would then call this OAL dimension zero, or just touching the lands. Therefore 0.010" into the lands would be 0.010" longer.
 
#3
Re: Measuring for Lands

I was always under the impression that you didnt want to load into the lands but rather keep it .010 OFF the lands. So you would take your measurement from where the ogive hit the lands then subtract .010 from that measurement.
 
#4
Re: Measuring for Lands

glock 24, that is about what i do, but in reverse, i start too long and keep backing off until the marks go away. then reverse the process in finer increments to double check, i have also checked headspace that way, i/e set headspace off of sized brass, then used a go/no go guage to see how close my sized brass is to the "spec" of the guage.
 
#7
Re: Measuring for Lands

heres a quicker way...close the bolt, stick a cleaning rod down the bore til it hits the bolt..mark the rod w a piece of tape at the muzzle. pull it out, open the bolt, have a buddy hold a bullet against the lands w/ a short rod or something. stick the rod down the bore again until you hit the meplat, and mark w/ tape the same way. knock out the bullet, pull the rod out. Measure from front edge of tape to front edge of tape = COAL to lands.
 
#9
Re: Measuring for Lands

I use a case that has used a sizing bushing that was too large to hold the bullet tightly. I then stick the bullet I am interested in softly into the case and then chamber it. With the right amount of tension, the oal on the shell will be exactly at the lands. With not enough neck tension, the bullet remains in the lands (I then change bushings and repeat). I then take that measurement and either add or subtract as needed for my distance to the lands. I then use that same bullet to set up my die- that way I get ogive measurements.
 
#10
Re: Measuring for Lands

I almost do like above, except I use a fired case and dent the neck slightly w/my teeth to hold the bullet.... Do several times so you are confident in the measurement and be careful you don't seat deeper w/the caliper.

On some of my chambers I have a partially chambered "gage", and I can use the gage to adjust the seater to seat right at the throat when shoulder is against the gage. Gage may cost an extra $35 when I get the chamber done, but I think money well spent (it checks brass headspace, seating, and trim length).

Cheers,

Bill
 
#11
Re: Measuring for Lands

I used the sinclair tool and got the following with 155gr Scenars:

AR10 w/ 21" Noveske barrel: 2.856"

Factory Savage 10FCP McMillan: 2.848"

I really expected to find some longer chambers. I wouldn't have minded in the case of the Savage, I measured the inside of the DBM and it appears that possibly up to 3" of COAL would fit.
 
#12
Re: Measuring for Lands

http://www.dillonprecision.com/content/p...e_Modified_Case

You can buy it at pretty much anyplace you buy your reloading gear. You also buy the "dummy" round which is a factory new case that threads onto the gauge and insert any bullet that you want to use. Slide it into the chamber and feed the cable until the bullet touches the lands-lock it and measure and... wala.

Invaluable tool for jump to lands measurement on what ever bullet you are using at the time and you can also keep an eye on throat erosion too!
 
#13
Re: Measuring for Lands

A cool thing that my 'smith did for me when I rebarreled my rifle was when he took the 1" to 2" off the end of the barrel for crown and muzzled work, he saved that cut off pieces, cut my exact chamber and headspace into the piece. Now I have a "tool" that allows me to get my exact headspace, and lenght to the lands. I thought that was pretty cool of him. I have also used the stone point gages and they work fine too.
 
#14
Re: Measuring for Lands

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ewoaf</div><div class="ubbcode-body">heres a quicker way...close the bolt, stick a cleaning rod down the bore til it hits the bolt..mark the rod w a piece of tape at the muzzle. pull it out, open the bolt, have a buddy hold a bullet against the lands w/ a short rod or something. stick the rod down the bore again until you hit the meplat, and mark w/ tape the same way. knock out the bullet, pull the rod out. Measure from front edge of tape to front edge of tape = COAL to lands. </div></div>
That's exactly how I do it, except that I purchased two nylon bushings that fit perfectly over my cleaning rod...tapped them and installed a nylon "lock" screw on each one.
 
#15
Re: Measuring for Lands

You need a measuring tool, Sinclair or Stoney Point (Hornady), so that you can MEASURE the distance. Without that, and without keeping accurate records, you won't really know anything or be able to replicate anything.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: NativeCraft</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ewoaf</div><div class="ubbcode-body">heres a quicker way...close the bolt, stick a cleaning rod down the bore til it hits the bolt..mark the rod w a piece of tape at the muzzle. pull it out, open the bolt, have a buddy hold a bullet against the lands w/ a short rod or something. stick the rod down the bore again until you hit the meplat, and mark w/ tape the same way. knock out the bullet, pull the rod out. Measure from front edge of tape to front edge of tape = COAL to lands. </div></div>
That's exactly how I do it, except that I purchased two nylon bushings that fit perfectly over my cleaning rod...tapped them and installed a nylon "lock" screw on each one. </div></div>That won't work. You don't need the distance between the bolt face and the bullet tip. You need to be able to measure, within .001, the distance between the case head and the bullet ogive.


 
#16
Re: Measuring for Lands

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Graham</div><div class="ubbcode-body">That won't work. You don't need the distance between the bolt face and the bullet tip. You need to be able to measure, within .001, the distance between the case head and the bullet ogive. </div></div>
It will work if you want to keep tabs on throat erosion and always use the same bullet for measuring, won't it. If the bullet is sitting against the lands (on its ogive), and you measure to its tip, that will give you the OAL for that bullet, right?
 
#18
Re: Measuring for Lands

For years I used the cleaning rod and tape method until I got my Stoney Point. Always worked until I got my .260 built. I didn't have the Stony point .260 casing yets so I used the rod method.

Silly me, I got spoofed on my measurement. I inserted the cleaning rod and inserted until I felt the bullet and taped and measured the tape. Turns out I was 0.037 short. I had loaded a bunch of 142 SMK's and didn't get the accuracy I was looking for.

I found that my .22 caliber Dewey rod tip was slipping under the tip of the bullet and referencing off the ogive just in back of the tip. The .22 rod isn't wide enough to reliably hit the bullet tip! Should have bought the bore sticks rod!

When the .260 modified casing from Hornady came in I found the discrepency and I wanted to know where I went wrong on the old cleaning rod method. you got to use the right size rod!

- You still have bullet tip variance to deal with too.
 
#19
Re: Measuring for Lands

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: glock24</div><div class="ubbcode-body">I'd like some clarification too . . .

My current procedure is to slowly increase OAL until five symmetrical marks can be seen around the ogive of a dummy round with a bullet that has been dipped in blue die maker's ink and then chambered.

I would then call this OAL dimension zero, or just touching the lands. Therefore 0.010" into the lands would be 0.010" longer. </div></div>

I have been told to never use any sort of marker or ink on bullets or the cases. They can cause pitting and unwanted problems in a bore or a die. What i do is use steel wool to scuff up the bullet and continue to seat deeper until the lands barely make marks on the bullets.
 
#20
Re: Measuring for Lands

Get a Sinclair case length guage. The kind you put in the end of a case to determine your chamber case length.

Turn the head of it down to your bore dia.,(.3080,.3380,.4080), use it the same as you would for case length but it will give you the dimension from bolt face to rifling.

<span style="text-decoration: underline"><span style="font-weight: bold">It is best to take this measurement in your new rifle before you fire the first round</span></span>.
 
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