finding the coal of my rifle

[stevesmith]

im new to reloading rifle bullets,,ive loaded thousands of 12 guage shot shells but never bullets..i need to know the least expensive way to somewhat measure to where i can safely load the bullet in the brass in direct reference to the lands.. ive heard this term of (coal) used quiet a lot..i understand what it is just ive heard so many different ways to do it that it gets confusing..as of right now im not wanting to be a pro at it so i just want to know how to measure it the least expensive way to be safe. as time goes ill get better and buy more..just starting out is expensive..bought the savage 110ba 338 lapua and have about 150 rounds through it..as you probably know they are a very expensive round so i need to load my own for that reason..if anybody has good ideas..god recipes etc.. i sure would appreciate any knowledge from anyone who has done it and will tell me anything about there process..
thanks in advance for your time in this matter,,
i hope you have a blessed week...

[Bart B.]

If you'll load them from the magazine, make a dummy round; seat a bullet in an empty sized case so the cartridge length is 1/16" less than magazine length. Then put it in the magazine and load it.

If the bolt closes easy on it, that is what will function best in your rifle. If not, remove the round, make another dummy round 1/32" shorter then try it the same way. Repeat this if needed. Good enough for 338 Lappymags.

[Gster]

I would start with published oal for the load you choose and check for accuracy. A cheap way to measure to your lands is to slightly neck size a case(without a live primer) from a round that you fired in your gun, so that a bullet will be snug but still push into the case as you carefully close the bolt on your gun. Then simply open the bolt gently so the cartridge doesn't eject out on to the floor. Lift it out and measure. Do it a few times to get an accurate measurement. This worked for me and I now load them 10/1000s shorter than touching the lands. I did all this after I found an accurate charge. Hope this helps. You'll get a lot more methods here shortly I'm sure.

[olddav]

What you don't want to start with a 50 BMG? The way I find max bullet length is take a deprimed resized brass case and insert a bullet, seating it long. Insert it into the action and try to close the bolt, (gentle like). If bolt resist closing, seat the bullet just a little deeper and try again, repeat till bolt closes. At that time I Seat the bullet deeper still, (I don't like the bullet jammed against the lands).
I got to shoot a Savage 110BA chambered in 338 Lapua, man oh man.

Good luck and for crying out loud be safe!

[Woolecox]

The way I find max bullet length is take a deprimed resized brass case and insert a bullet, seating it long. Insert it into the action and try to close the bolt, (gentle like). If bolt resist closing, seat the bullet just a little deeper and try again, repeat till bolt closes. At that time I Seat the bullet deeper still, (I don't like the bullet jammed against the lands).

That is a great and very accurate way to do it. Take the firing pin out of the bolt for better feel. If you jam it in there too hard, the bullet can stick and be pulled out of the case. Start over.

Tony Boyer would put extra neck tension on this test case, polish the bullet ogive with scotch brite, and put a little lube on it. He would then get a slight jam into the lands. Hopefully, the bullet stays put in the case when it is extracted.

You can now use a bullet comparator to measure exactly how deep your chamber's throat is. Dial your seater back .003” and that is a good place to start.

Just remember that as the throat erodes, you will have to remeasure.

The problem is that the magazines in most factory rifles will not accept cartridge OAL’s long enough to reach the lands. I have a Rem 700 in 7mm Mag that will because the action and magazine are the same as for a 300 Win Mag which is longer. Bonus.

[Unclenick]

Stevesmith,

Several home brew methods exist. Just understand that a bolt will usually close on a light jam into the lands of the rifling. This is used by many shooters to help align bullets. It tends to cause pressure to go up by about 20% over what the same load produces with some jump into the lands, about what a 8-10% increase in powder charge would be likely to produce. Also, as a loading method it is only most accurate with some bullet designs and not others. The main point is that if you load this way, your powder charges need to be worked up carefully, as minimum charges in much load data will be maximums for jammed bullets.

The first home gauging method I heard of was to size a case the way you normally do, and split the neck with a hack saw. The idea is to have a neck that gets a friction grip on the bullet, but that still allows it to slips under finger pressure.

Once you have the case, note that there is some variability in bullet length in many bullet designs that can affect your measurements by up to a hundredth of an inch or so. To handle that, select several bullets from your box that measure to be the same length and use these to measure maximum overall length of the cartridge and to set up your seating die to match it. Since most bullet seating stems push on the ogive of the bullet, other length bullets won't give you an exactly matching COL, but the portion of the ogive that contacts the lands will be in the same position within two or three thousandths, allowing for bullet tooling differences.

Remove the bolt from the gun and set it on a cleaning cradle. If you don't have one, prop the gun up on sandbags or cut a couple of large V notches in opposite sides of a sturdy cardboard box and set it into those. Set one of your matched length bullets into the split neck of the modified case sticking out way too far. Press the split case and bullet into your chamber with your thumb or leave the bolt out and use a dowel rod to push it in until the case shoulder stops against the end of the chamber. This is the position a cartridge will have during firing because the firing pin drives the cartridge forward. You should feel the bullet being seated by the chamber if you use your finger for this.

Next, take a cleaning rod or small diameter dowel that fits your bore, and gently push it in from the muzzle and push the bullet and case out slowly with this so as not to disturb the position of the bullet in the split neck. With this split-neck dummy removed, measure its length. That is the COL at which the bullet touches the throat. Seat the bullet in a live cartridge out 0.010" longer, and you will have 0.010" jam into the lands. Seat it out 0.030" shorter and you will have a cartridge 0.030" off the lands.

Note that some chambers have freebores so long you cannot seat a bullet out to touch the lands and still fit the the finished cartridges in a magazine, as Bart described. Such rounds have to be loaded singly. Note that some freebores are so long that a short bullet cannot be seated out to touch the lands and still be inside the case mouth. But these anomalies aside, you now have a method of controlling the seating distance of the bullet ogive off the lands. This, however, begs the question, what should you control it to for best precision on target?

The answer to that question rests in load tuning. Berger recommends seating 0.010" jam into the lands and developing a best accuracy load that way first, then backing the bullet out in 0.030" increments (target accuracy; they used 0.040" increments for hunting accuracy, though I don't know why you'd want to distinguish between the two) looking for groups to tighten. The problem with this is the pressure and barrel time change with seating depth. So you don't really know if you are tuning a best seating depth or a best barrel time. Two methods of trying to avoid that issue are to adjust powder charge for best accuracy for each bullet position. This is usually close to the charge weight at which velocity matches, but not exactly. It falls somewhere between the charge weight that makes velocity match and the charge weight that makes peak pressure match. Or you can tune the loads for smallest group.

Another strategy is just to avoid causing much muzzle disturbance by using a very light load made using Trail Boss powder filling the empty space under the bullet by around 90%. These light reduced loads produce very limited recoil and muzzle ringing. I have not, however, compared the results carefully to full powder charges to verify the optimal seating depth remains exactly the same under the more stressful dynamic conditions of a full pressure load. This is an area open to further experimentation.

Be aware the firing pin blow can shorten some cases several thousandths more, in effect sizing them down a little in the chamber. Between that and bullet variability, figure you can, at the moment the powder ignites, expect to be able to achieve real consistency of around 0.005" to 0.010" off the lands, but no tighter. People who think they are seating 0.005" off the lands are actually getting rounds anywhere from that to touching the lands at the actual firing event. For this reason, trying to tune seating depths to a greater precision than 0.010" is likely to prove to be a fool's errand.

Bullet and cartridge terminology might be useful to review. The term overall length, with initials ol, refers to the total finished length of a cartridge. Prior to the 1950's, dictionaries gave the word overall in hyphenated form, over-all, when it referred to length, and so it then had the initials oa. Until then, the compound form, overall, was only used to mean all things considered. After the 1950's, the hyphenated form disappeared from dictionaries, having became obsolete.

Today, you see the initials for Cartridge Overall Length, the full term, as COL. It used to be COAL when the hyphenated form was still current, and a lot of publications have never got out of the habit of using the initials for the hyphenated form. Some folks drop the "Cartridge" to leave OL and some use OAL for that same reason, but still using the obsolete form of the last part of the term. A few folks confuse that last version with the Internet service, America On-Line, and give you AOL. Interestingly, on-Line is another word, like e-mail, where the hyphen has been dropped since that company was founded (but they aren't changing the name spelling now). The Chief Editor at the Merriam Webster dictionary says hyphenation is gradually falling into disuse in English in general.

[rsnell]

All the responses to your inquiry are good. If you want to use a tool to measure the COAL, Sinclair sells a very simple one. The part number is 749-004-650WS and sells for $23.99. This is the one I use. It is very versatile, accurate, and easy to use.

[mehavey]

Simplest get-off-the-ground method:

Req'd:
1. Bullet
2. Blunt-ended cleaning rod
3. New pencil w/ eraser end
4. Calipers


- Insert bare bullet into chamber/throat and gently hold against lands by pressing up against it with the eraser end of the pencil.
- Insert blunt-ended cleaning rod into muzzle and run it down to the bullet from the other direction.
- Push the bullet back & forth using both pencil & rod to gently get it up against the lands.
- With sharp pencil, mark the cleaning rod as exactly as you can at the muzzle.
- Remove bullet; run the cleaning rod all the way down to the bolt face; Mark it again at the muzzle.
- The distance between the two lines is your OAL-to-the-lands (± a few thousandths pencil/case sizing tolerance error)
- Subtract 30 thousands from that (~ paperclip diameter) and you have a starting point. (Check to see that the OAL still fits the magazine)

(Downstream, consider getting the likes of a Hornady OAL Gauge Set.)

[Bart B.]

One variable that'll cause a small spread in bullet jump to the rifling with cases headspacing on their shoulders. If case headspace has a .004" spread, that adds to the bullet reference to case head dimension spread. The case shoulder is hard against the chamber shoulder when it fires.

[T. O'Heir]

You have to work up the load for your rifle. No two will shoot the same ammo the same way, so what shoots well out of mine won't necessarily do so out of yours.
To find the length of your chamber, not the COAL, size and seat a bullet with absolutely no crimp or hint of one and chamber it. The bullet should be pushed back when it hits the rifling. Then you get to fiddle, by trial and error(there's no formula), with the COAL to find the length your rifle likes best.
It's another thing that is not the same in every rifle. Some will like 20 thou off the lands. Some more. Some less.
Personally, I've never bothered with it. I might if I had a high end match rifle. The max OAL with the bullet given in your manual works just fine. In any case, mucking about with the OAL is a load tweaking technique done after you have a load.
"...If case headspace..." No such thing. Headspace is a rifle manufacturing tolerance only.

[Bart B.]

SAAMI says there is such a thing as case headspace. So does the vast majority of the firearms and reloading industry. Just because it ain't in SAAMI's glossary doesn't mean it is not widely accepted and common terminology.

One ammo and reloading tool company says "little headspace" is the space between the bolt face and case head in one page of their web site ignoring SAAMI's definition of that is properly called "head clearance," then later on the same page they say "headspace" is the distance between the bolt face and whatever stops the cartridge's forward movement in the chamber. They make and sell a case headspace gauge shown in another section that helps calipers measure cases from head to shoulder reference point. Go figure that out reading:

http://www.hornady.com/ballistics-resource/internal

[condor bravo]

From the OP it wasn't that clear whether the request was for determining the COAL from bolt face to rifling for a particular rifle or determining OL for best accuracy; perhaps both and both have been covered in this thread. For another method in determining COAL from bolt face to the rifling (touching the lands lightly), I have a post entered in the current thread titled COAL that you might want to acquaint yourself with.

[RC20]

I would simply get the pretty low cost Hornady comparator (you might have to order the so called modified case for the 338 Lapua as that is not a common carried one)

It takes all the futzing around out of it, I have found it far more accurate and you can use it on any other gun by getting the right modified case for it.

Go with something between .010 and .005 shorter than it shows. Not familiar with the 338 Lapua so go with Bart B and that seems to be up close to the rifling.

[Tipsy Mcstagger]

Lots of good stuff here, but if it wasn't said or wasn't obvious I want to make sure you know that your coal will differ with each bullet type, since the bearing surfaces are in different places for different bullets. That matters if you're not loading book coal and trying to seat the bullets further toward the lands. I use the sized case with 4 neck cutouts a bullet or two, calipers, and the bolt to figure out where a bullet type touches the lands.