Finding distance to lands

[Brians356]

IMO, the R-P tool is/was the best for finding touching w/resp to your bolt face. Its a version of the 'cleaning rod method'.
Look over Woods post here for pics and instructions: http://www.reloadersnest.com/forum/topic.asp?TOPIC_ID=9027
Maybe you can make or find a version today.

I read that thread, wondering where the name "R-P" comes from, didn't find out. It suggests Remington-Peters in my feeble mind. I seem to recall Fred Sinclair pictured with that setup.
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[Richard Jones]

See Alex Wheelers video of Tom Mosel's way of checking seating depth. It is the most accurate way of doing it. Matt

Why?

Not arguing, just asking.

 

[dkhunt14]

Why?

Not arguing, just asking.

I believe it is the most accurate way. If using a case or Hornady tool, it puts pressure on the bullet. It takes almost zero pressure to push a bullet into the lands. MATT

 

['Freak]

Of the ‘store bought’ thing-a-ma-jigs, I prefer Sinclair’s Bullet Seating Depth Tool #749-004-650. You’ll work a stainless steel rod through a Delrin guide (no “special case” ever involved) while shoving directly against either the base of a bullet or, in a separate 2nd step, against the case head of any case you’d choose but ideally a case already fitted to be completely filling the bolt face to shoulder datum length of that chamber.

Two stop collars will be set in position on the stainless rod. The first is set representative of the distance to the base of a bullet ‘just touching’ or ‘hard jammed’ or …, and the second collar is set representative of the distance to the head of a case whose shoulder is held firmly shoved into the taper of the chamber’s shoulder.

A measurement from the first to the second stop collars gets you the distance from the case head to the base of the bullet. Add to the first measurement the bullet’s base to ogive length obtained via the use of a bullet comparator, and that result is a would-be loaded round’s case head to bullet ogive length.

 

[Drop Port]

You will get varying answers so what ever method you feel comfortable with that has repeatable measurement will work for a base line.

I use a Stoney Point / Hornady tool with a piece of brass fired in my chamber and a 5/16 x 36 tap. While taking measurement I've found the rifle MUST be held vertical to get consistent readings, with the case shoulder held firmly forward contacting chamber shoulder I can raise the seater stem getting a good feel of the bullet touching the lands. With this method I can raise the projectile feeling the weight o the bullet on my finger and an ever so slight pressure when contact is made with the lands. 5 (five) readings within .001 and I'm done. I can also use increasing light pressure to the point the bullet just hangs in the lands for repeatable readings between touch and light in.

Just my .02 I like the feel I trust my touch sensation.

I then take notes and keep the bullet used for the test in the die box for erosion testing down the road.

 

[hogpatrol]

Was watching football and missed this thread or I would have broken out the popcorn with the OP. I use Alex's method, firing pin and ejector/spring removed.

 

['Freak]

Is there somewhere a text description of the method shown on the “Alex’s Video” …? Thanks to my dialup infernal.net so called service, I can’t watch this or any other of so often recommended video tutorials.

 

[XTR]

I have found something that works well for me.

I pull the barrel. Seat the bullet, push it in the chamber with my thumb, if I can't pull it with no resistance using my fingernail, its in the lands. I know what is close with my Hornady tool, so I start pushing back .001 at a time with my Wilson die, drop it in, pull it out, repeat till you can take it out with your fingernail. I have to use a small flat bladed screwdriver till it's not in the lands. Usually takes about 5 minutes.

I get much better feel that way than with the bolt, and I find it easier to pull the barrel than the pin and depending on the rifle the ejector.

 

[PMA3]

Of the ‘store bought’ thing-a-ma-jigs, I prefer Sinclair’s Bullet Seating Depth Tool #749-004-650. You’ll work a stainless steel rod through a Delrin guide (no “special case” ever involved) while shoving directly against either the base of a bullet or, in a separate 2nd step, against the case head of any case you’d choose but ideally a case already fitted to be completely filling the bolt face to shoulder datum length of that chamber.

Two stop collars will be set in position on the stainless rod. The first is set representative of the distance to the base of a bullet ‘just touching’ or ‘hard jammed’ or …, and the second collar is set representative of the distance to the head of a case whose shoulder is held firmly shoved into the taper of the chamber’s shoulder.

A measurement from the first to the second stop collars gets you the distance from the case head to the base of the bullet. Add to the first measurement the bullet’s base to ogive length obtained via the use of a bullet comparator, and that result is a would-be loaded round’s case head to bullet ogive length.

Freak,

I have used the Sinclair tool since it came out about 35 years ago. Last year I switched over to the "Wheeler" procedure and found by comparison that what I thought was the "touch point" with the Sinclair tool turned out to be, on average, about .008"-.009" INTO THE LANDS.

With the Sinclair tool, just tapping the bullet base A LITTLE BIT DIFFERENTLY with the steel rod can result in a .005" or more variance. This can't happen with the Wheeler procedure.

Paul

 

[Delfuego]

Thanks for the info Paul. I use the Sinclair tool and will pay much closer attention to the results now.

 

[Brians356]

Of the ‘store bought’ thing-a-ma-jigs, I prefer Sinclair’s Bullet Seating Depth Tool #749-004-650. You’ll work a stainless steel rod through a Delrin guide (no “special case” ever involved) while shoving directly against either the base of a bullet or, in a separate 2nd step, against the case head of any case you’d choose but ideally a case already fitted to be completely filling the bolt face to shoulder datum length of that chamber.

That's the Sinclair rig I was picturing. nearly identical to this so-called "R-P" since it is just two set collars on a rod.
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[Thisguy65]

Alex's video of he states you have to be careful when the bolt is closed. Example at 1.765 the bolt goes down under it own weight and up as well, there is no felt camming of extraction but when I apply sharpie to the bullet it clearly shows the ogive touching the lands as seen in the OP.

 

[bobinpa]

Alex's video of he states you have to be careful when the bolt is closed. Example at 1.765 the bolt goes down under it own weight and up as well, there is no felt camming of extraction but when I apply sharpie to the bullet it clearly shows the ogive touching the lands as seen in the OP.

Alex's video/method is a very accurate way of finding the lands, if you know what you are looking for. In my opinion (and I'm only trying to help) I don't think that the mark you are getting is from a land. To me it looks too long and it almost looks like it is behind the ogive, but I may be wrong. The mark in the picture appears to be from the bullet touching the side of the chamber/throat on the way in or out, like as if the ejector is pushing it against the side of the chamber. Assuming that you took the ejector out, clip the round on the end of the bolt instead of just pushing it in with the bolt, like in the video. When I use Alex's method, I use a piece of scotch bright pad to scuff the surface of the bullet. I usually get the same number of marks on the bullet as I have lands in the barrel and with a scuffed bullet the marks are easier to see because they are shiny. I seat the bullet in a sized case and close it in the chamber with the bolt. I take it out, seat it deeper, re-scuff it and repeat the process until I can barely see the marks with a magnifying glass. To me that is close enough to call my "touch" number. I only do this for some of my guns. The other guns I have the "gizzys" that Butch described. Using those makes it way easier and way faster. The next time you get a gun chambered have your smith make you a gizzy with the same reamer and you won't have this headache, .

 

[Ned Ludd]

Regardless of the method used, most reloaders will ultimately determine on the target what the optimal load parameters for their specific setup actually are. Actual measurements of proven rounds are relatively accurate and easy to reproduce. In contrast, initially finding the distance to the lands is much more of a "relative" measurement used as a starting point for load development. For that reason, whichever method someone prefers is fine as long as it works and they're happy with it.

As long as the initial estimate is within about .005" or so, subsequent testing using actual targets as the readout largely renders the relative inaccuracy of different methods moot, with at least one notable exception. If your seating depth testing involves seating bullets at or very close to the lands, inaccuracy in the initial distance to the lands measurement might put the bullet as much as .005" into the lands when it is only believed to be just touching. It is certainly possible in some cases that overpressure issues could be the result, particularly if the optimal charge weight had already been determined at a seating depth farther off the lands.

I use the Hornady OAL gauge and have been very satisfied with the results. It takes a bit of practice to develop a good feel for the using the tool properly, but really isn't very difficult to determine when the bullet just touches the lands IMO. I pick 10 bullets from a new Lot at random, label them #1 to #10 on the bottom with a Sharpie and use them as a "measurement set" for that specific Lot of bullets as long as they last. I measure bullet OAL, then determine CBTO and COAL at "touching" with all 10 bullets, then determine the average +/- SD for each measurement. I use the "average" CBTO and COAL measurements at "touching" as my starting point for load development and QuickLoad. My typical mean CBTO values at "touching" have SDs of about .001". Due to bullet OAL variance, the mean COAL SD values for the same 10 rounds are usually around .002" to .003". I typically start charge weight testing at .015" off the lands, well outside the likely measurement error. I typically test seating depths from .006" off to .024" off in .003" increments, so it is unlikely that my initial "touching" measurement with the Hornady tool is off by enough to actually put the bullet at the longest seating depth depth into the lands.

 

[rardoin]

Alex's video of he states you have to be careful when the bolt is closed. Example at 1.765 the bolt goes down under it own weight and up as well, there is no felt camming of extraction but when I apply sharpie to the bullet it clearly shows the ogive touching the lands as seen in the OP.

Keep in mind that the marker you are using has a thickness to the applied coat. At the 1.756" depth you have found the 'Sharpie coat to lands" distance. Try eliminating the marking pen and going solely by feel. I think you will find a consistent 'distance to lands'. To illustrate how that marker thickness can affect the result, try coating an ogive on a seated round and measure with a comparator insert/caliper with a light touch. Clean off the markings with alcohol and repeat the test with the same 'touch'. I'll bet you find a difference of a couple of thou's.....

 

[BoydAllen]

I prefer not to use methods that require disassembly of the bolt. Throats move, and as long as I can get reasonably repeatable results from a given method, that is all that I need. It does not matter that I am not starting exactly at touch, because I am going to try different seating depths in relation to that starting point, and as long as I can get to that starting point reliably, there is no problem. For instance, if my Sinclair rod and stop collar measurement is actually .003 into the rifling, as long as that repeats reasonably well, I can get from there to where ever the rifle wants to shoot best. If it wants to shoot at actual touch, experimentation will show that I need to shorten my ogive length by .003 from my initial measurement. I AM careful to note the method I used to come up the initial measurement, whether it be the Sinclair tool, or the Stoney Point (now offered by Hornady). I also note the tool and insert used to measure off of the ogive. In reading these discussions I have come to the conclusion that some people like complication, and that perhaps the outside temperature and snow depth may also be factors.

 

[bsekf]

"I have come to the conclusion that some people like complication, and that perhaps the outside temperature and snow depth may also be factors".

I agree with Boyd....... and since I believe in KISS, I use the bullet in the case method. Just take several reading to make sure the bullet isn't sticking in the rifling. I use the Hornady comparator and have a good scale. It's just a starting point!

 

['Freak]

Since the Sinclair thang-a-ma-jig frees up a hand vs. using the Hornady/Stoney Point tool, when “attempting” to feel out the point of first ogive contact, instead of gravity and luck alone I’ve also tried a cleaning rod from the muzzle end opposing the Sinclair rod working the bullet’s base, allowing some back and forth action. I’ve tried both barrel horizontal and with the barrel vertical, both muzzle up and with the muzzle pointed down.

Whichever of these two tools, it still all boils down to a “matter of feel”. With Sinclair’s tool, and it figgers also the R-P tool, utilizing an opposing force so you can sneak up on what feels is first contact, back off a tad, sneak in on it again and repeat ‘til it “feels it’s repeating”, then lock in the collar’s setting, and the more likely the numbers I get will be repeatable, more so than what I can manage using the Hornady/Stoney Point tool.

Is the “just touching” reference number I get fer real? Probably not, lookin’ it’s possibly if not more likely a couple or four or maybe more thousandths into the lands, depending on the ogive’s profile. With what and how I shoot right now, don’t really matter. It’s mostly just a reference number for keeping track of various seating depths relative to their effect at the target. But hopefully someday such things will matter and I wanna be ready …

I’d still love to read a text version covering the highlights of the Alex Wheeler ‘how to’ video.

 

[rardoin]

I also agree with Boyd. Any consistent method to get a repeatable reference point and determine which seating depth works best relative to that position. In a factory action with a plunger ejector, I find the Hornady/Sinclair tool is easiest. In ejectorless R700 based actions I own, it is easier and more repeatable for me to use the method as described in Alex's video.

 

[dkhunt14]

What difference does it make when you can just go do load development again


Tom

In your words, you told me that some of your guns came alive in as little as .003 bullet movement. I can't measure that with a Hornady. I just used the 20 difference as a reference number. My 300 WSM doesn't move .005 in 1000 rounds, so no need to do load development again. Matt