COAL

[Webster]

I have tried every method to find touch. I keep coming back to the split neck method. I get the impression that if you have erosion the rifling doesn’t have sharp edges to mark the bullet.

Split neck method:
It seems that you may have to have an ideal neck tension to get good results?

I plot in Excel the starting COAL, record the extracted COAL and plot starting COAL VS how far the bullet was pushed in. I eliminate the few obvious bad numbers or pushed in results. Most of the results are no more than 3 thou from the best fit line. If the results don’t pass through zero you can use the formula to determine COAL at Zero (touch). I keep adjusting the start COAL with pliers on the nose to get a spread of numbers in the correct range. Chart for a 58 GR VMAX, 0.065" freebore.

 

[Texan]

I don't have it or use it, but have you tried using Hornady's tool with the modified cases?

Like you, I've used a sized case with the split/slit neck for a long time, but have also been looking at alternatives (including the Hornady tool).

I've decided that I'm going to make my own tool using an appropriate diameter brass or nylon rod with two collars with set screws.

To measure, you would close the action and lock one collar down with the rod touching the back of the breech.

The next step, the action is opened and a bullet is inserted (with or without a case), and the second collar is locked down with the rod touching the bullet tip.

Next you measure between the two collars and make a dummy cartridge with the same bullet used in the initial measurement, then measure the OAL off the ogive to find the true distance to the lands.

 

[ED3]

I don't have it or use it, but have you tried using Hornady's tool with the modified cases?

Like you, I've used a sized case with the split/slit neck for a long time, but have also been looking at alternatives (including the Hornady tool).

I've decided that I'm going to make my own tool using an appropriate diameter brass or nylon rod with two collars with set screws.

To measure, you would close the action and lock one collar down with the rod touching the back of the breech.

The next step, the action is opened and a bullet is inserted (with or without a case), and the second collar is locked down with the rod touching the bullet tip.

Next you measure between the two collars and make a dummy cartridge with the same bullet used in the initial measurement, then measure the OAL off the ogive to find the true distance to the lands.

I use the rod and shaft collar method. I use a cleaning rod, and 'machined' (ground flat with file and drill press) the head of a round head brass bolt that fits the cleaning rod. I found the cheap, plastic rod stops commonly available would not consistently square up enough for repeatable measurements. I bought metal shaft collars from local hardware store

There are some important details to this procedure that I can't type out on my phone, but there are numerous references and tutorials around the interwebeses.

 

[hogpatrol]

Every method including the stripped bolt? After I use that method then I use the Hornady tool and I'm within .002 of the stripped bolt. I haven't found anything more consistent.

 

[Richard Coody]

i have no problems with the stoney point. for me it is quite easy and repeatable within .002.

it is really how you use the tool. when you first push the bullet in you will feel a point where you feel resistance. in my opinion that is the bullet going into the throat and freebore. Many methods will call that the lands. if you give another little push the bullet will move forward and stop with firm resistance. i go so far as to tap the back of the rod lightly knowing this is driving the bullet into the lands. extract the tool without the bullet and push the bullet out with a dowel rod or your cleaning rod. drop it in the tool and measure. that measurement is accurate and repeatable

 

[ED3]

Every method including the stripped bolt? After I use that method then I use the Hornady tool and I'm within .002 of the stripped bolt. I haven't found anything more consistent.

"...the stripped bolt?..."

Would you elaborate, please?

Thanks

 

[hogpatrol]

"...the stripped bolt?..."

Would you elaborate, please?

Thanks

First post, video instructions.

http://forum.accurateshooter.com/threads/finding-the-lands.3892416/

 

[Webster]

i have no problems with the stoney point. for me it is quite easy and repeatable within .002.

it is really how you use the tool. when you first push the bullet in you will feel a point where you feel resistance. in my opinion that is the bullet going into the throat and freebore. Many methods will call that the lands. if you give another little push the bullet will move forward and stop with firm resistance. i go so far as to tap the back of the rod lightly knowing this is driving the bullet into the lands. extract the tool without the bullet and push the bullet out with a dowel rod or your cleaning rod. drop it in the tool and measure. that measurement is accurate and repeatable

I have a stoney point. Always got a huge scatter in numbers. I don't think the case seated in the chamber the same way each try.

 

[Webster]

I don't have it or use it, but have you tried using Hornady's tool with the modified cases?

Like you, I've used a sized case with the split/slit neck for a long time, but have also been looking at alternatives (including the Hornady tool).

I've decided that I'm going to make my own tool using an appropriate diameter brass or nylon rod with two collars with set screws.

To measure, you would close the action and lock one collar down with the rod touching the back of the breech.

The next step, the action is opened and a bullet is inserted (with or without a case), and the second collar is locked down with the rod touching the bullet tip.

Next you measure between the two collars and make a dummy cartridge with the same bullet used in the initial measurement, then measure the OAL off the ogive to find the true distance to the lands.

Something I tried was taking a barrel stub about 1" long and inserting a bullet and rotating it so the lands scratched the ogive at the land diameter. If you measure the height of the bullet and the stub together and subtract the stub height you get the distance of the land contact to bullet base length. Also you know the portion of the bullet in the barrel with no contact. I gave up when I realized the stub didn't have parallel ends, off by about .015". Don't think freebore is involved in the math? You end up with the land contact to case end distance and a bunch of other numbers. Not sure but I think you could calculate the touch COAL for any bullet without the rifle? The distance from the ogive with the ogive touching the land to the case neck is always the same distance no matter what bullet is in the rifle. Bigger bullets just go farther into the case. You could probably calculate COAL by this method to within a couple thou. I gave up and went to the split case method.

Added later: I think something serious was left out of the process. I think you also need a good COAL determined with the rifle with one bullet as a reference. Too much gray matter required. Then you can do any bullet mathematically? Assumed the distance from the ogive touching the lands to the case neck doesn't depend on the freebore, the distance is the same for any bullet. The case is in a fixed position and the ogive is always touching the lands. Sounds interesting but I am not willing to spend more time on it.

 

[BillPa]

Split neck method:
It seems that you may have to have an ideal neck tension to get good results?

What I found to get consistent measurements with a split neck case.....
Before starting make sure the splits extend past the neck-shoulder junction into the shoulder a bit.
1. Size the neck using a FL, neck or bushing die.
2. Start a bullet in long, chamber, but don't extract it. Alternate between lifting and re-locking the bolt two or three times then extract it.
3. Pull the bullet out a little, maybe only .010-.020".
4. Chamber it but again don't but don't extract it, close and lift the bolt on it two or three times then remove and measure it.
5. Repeat step #4 two or three more times measuring each time.
6. Log the measurement for "that" bullet.
The reason to size the neck before each and every use, it's tension is the same every use and by only pulling the bullet out only a 10-20 after its initially seated long the tension remains as close as possible constant.

Bill

 

[Richard Coody]

I have a stoney point. Always got a huge scatter in numbers. I don't think the case seated in the chamber the same way each try.

i can see how that could cause a problem.

to each his own

 

[ED3]

First post, video instructions.

http://forum.accurateshooter.com/threads/finding-the-lands.3892416/

Of course,
Thanks.
When I read 'stripped bolt', my mind went a vision of a fastener with bad threads.

 

[bloc]

Of course,
Thanks.
When I read 'stripped bolt', my mind went a vision of a fastener with bad threads.

My first thoughts went to . . . someone a much younger guy might find in a bar . . .

 

[Ned Ludd]

I have a stoney point. Always got a huge scatter in numbers. I don't think the case seated in the chamber the same way each try.

Try practicing more with it, feeling for that first light touch. Use the same bullet repeatedly until you can obtain reproducible measurements with that one bullet. That's what I did when first starting out with the Hornady OAL gauge...I've used one for years now and it's as reproducible as almost any measurement I make in the reloading process. I've seen a variety of different methods posted here over time, but none IMO is any easier than using the Hornady OAL gauge. Once you get the hang of it, its use should be almost second nature.

Regardless of the method you use, the resulting value obtained is by nature at best relative. It will change as the lead smooths and erodes over time. It can change due to ogive variance even between bullets from the same Lot #.

The idea is to find a reasonably close value, which can then be used as a working start/set point. After that, all critical reloading measurements and firing analysis are done off of actual loaded rounds, so the measurements translate directly to whatever you might see on the target and can be reproduced with great precision. Because it's a relative measurement, it doesn't matter much if your working (start/set) distance measurement to the lands is off by a couple or even three thousandths, even though it's possible to be more precise than that with the Hornady tool, IMO. Once the working distance to the lands is set, you can reproduce any seating depth relative to that measurement to within .001" and will determine from the target what shoots best. Direct test results on the target from actual loaded rounds that can be measured with very good precision are what is important. What difference does it make if the actual [true] measurement is off by a thousandth or two? No matter what method you choose, they will all be off by that much after a hundred rounds or so, or if your Lot of bullets has significant ogive variance, as most do.

When I first started reloading, I agonized over my inability to be able to take a direct and precise measurement of distance to the lands with the tools I had available. As a scientist, the idea of indirect or relative measurements did not sit at all well with me. However, I eventually got past it and except for the occasional [weekly] flare ups, the nightmares, disorientation, cold sweats, nausea, headaches, and need for daily medication, have mostly gone away .

 

[geraldgee]

Like many in here I use the stripped bolt method to get a base-line measurement of where the lands are. Once I have established that and I want to try a different bullet or I want to check/compensate for erosion, I use the Sinclair Seating Depth tool. I find it to be pretty accurate and repeatable.

Good luck.

 

[tenring]

"...the stripped bolt?..."

Would you elaborate, please?

Thanks

This explains the stripped bolt method:

The Stony Point (now Hornady) tool is not repeatable. A cleaning rod equipped with two stops as mentioned above, is ideal. Sinclair sells it with their own type rod.

One thing you need to heed: Do not force the bullet into the throat. With the rod and stops method, you can slowly move the bullet back and forth until it just barely kisses the lands. Write that down and repeat 5 times, average the results.

 

[Richard Coody]

This explains the stripped bolt method:

The Stony Point (now Hornady) tool is not repeatable. A cleaning rod equipped with two stops as mentioned above, is ideal. Sinclair sells it with their own type rod.

One thing you need to heed: Do not force the bullet into the throat. With the rod and stops method, you can slowly move the bullet back and forth until it just barely kisses the lands. Write that down and repeat 5 times, average the results.

opinions vary

 

[Milo 2.0]

This explains the stripped bolt method:

The Stony Point (now Hornady) tool is not repeatable. A cleaning rod equipped with two stops as mentioned above, is ideal. Sinclair sells it with their own type rod.

One thing you need to heed: Do not force the bullet into the throat. With the rod and stops method, you can slowly move the bullet back and forth until it just barely kisses the lands. Write that down and repeat 5 times, average the results.

I use the Hornady OAL tool and mod cases. I'm looking for a ball park number, 3 readings the same I call it good. Would someone explain to me why an exact number is needed? I still play with seat depth on a load, the number I found is my baseline.
I see and hear people talk about this, I usually ask if they save the bullet they used the first time for reference, usually no is the answer.

 

[T-shooter]

I use a different method and it works well for me. If I'm careful, I can get the same reading to .001" completely starting over and redoing the measurement. You'll need a cleaning rod close to the bore diameter, not a small diameter one in a larger bore. Then a couple drill bit stops that fit the rod. Also the open threaded end of one section of the rod will have to be plugged. Years ago I got a cheap kit to do this that came with plastic inserts that thread into the rod. The other parts weren't made well. Simply filling the end of the rod with epoxy will work as long as you don't need to use it for any other purpose. I don't strip the bolt. The end of the rod will fit under the ejector but needs to be checked to make sure you're not on the end of it. You can do this by pushing the rod in as you slide the bolt back (keeping both in contact) and look through the port.

Start by closing the bolt, inserting the rod carefully through the muzzle, slide a drill stop over until it firmly touches the muzzle of the barrel and lock it down. Pull the rod out and slide the second stop on. Seat a bullet in a bare case that's too long to chamber. Insert it into the chamber and push forward just until you feel it contact the lands. I use my finger and then slide the bolt up against it. I use a medium size rubber band to keep the bolt against the case just to hold it in place. Carefully insert the rod again until you feel it make contact with the end of the bullet. Slide the second stop against the muzzle (being careful not to push the bullet back, just light contact) and lock it in place.

Remove the rod and measure outside to outside on the stops. Then subtract the thickness of the last one you put on (#2 in the picture). This is your overall length. I always completely re-setup and run the test over to double check myself. If I'm over .001", I need to know what I did wrong. If you see rifling marks engraved on the bullet, or it tries to stick in the chamber, you inserted it too hard. Now take the same bullet and case, seat the bullet from the tip to the exact same overall length. Save this as a test dummy round and mark it for future reference. Measure this with a Hornady tool which measures at close to the bullet diameter (.298" on a .308). With the same lot of bullets, I can now adjust my jump by subtracting whatever I want from the dummy round specs.

With any different bullet, or the same bullet with a different lot number, you need to redo the test. Even with the same brand and part number can vary quite a bit.


I measure every loaded round with this tool.


This is how much different lots of the same bullet can vary. Measured with the tool above from both ends, one lot of these averaged .015" longer than the other.

 

[gotcha]

What I found to get consistent measurements with a split neck case.....
Before starting make sure the splits extend past the neck-shoulder junction into the shoulder a bit.
1. Size the neck using a FL, neck or bushing die.
2. Start a bullet in long, chamber, but don't extract it. Alternate between lifting and re-locking the bolt two or three times then extract it.
3. Pull the bullet out a little, maybe only .010-.020".
4. Chamber it but again don't but don't extract it, close and lift the bolt on it two or three times then remove and measure it.
5. Repeat step #4 two or three more times measuring each time.
6. Log the measurement for "that" bullet.
The reason to size the neck before each and every use, it's tension is the same every use and by only pulling the bullet out only a 10-20 after its initially seated long the tension remains as close as possible constant.

Bill

Being a fan of the split case method I'll add one more item to Bill's list.......... Try to advance and lock the bolt with minimum force, as little as necessary to get the job done. Once you've had a little experience with this item you'll be able to get as many as 6 to 8 measurements out of ten that match to within .0005" if not precisely ............. no lock rings, flimsy plastic rods as with the LNL tool and no need for COAL measurement conversions. Regarding BillPa's advice on sizing the split neck to maintain uniform tension, I've got a .223 case that I actually annealed it had been used so many times.