adjusting coal to the lands "methods"

[oley55]

I have been trying to decide what is the best method for determining (fine tuning) coal. Where to start; on the lands, .001, .002, .003, or where.

I just stumbled onto this 2009 article on the Berger bullets site. This article speaks specifically to the Berger VLD bullets, but why wouldn't it work on others?

http://www.bergerbullets.com/getting-the-best-precision-and-accuracy-from-vld-bullets-in-your-rifle/

the following is the last part of the article where the method is explained:

Trying to find the COAL that puts you in the sweet spot by moving .002 to .010 will take so long the barrel may be worn out by the time you sort it out if you don’t give up first. Since the sweet spot is .030 to .040 wide we recommend that you conduct the following test to find your rifles VLD sweet spot.

Load 24 rounds at the following COAL if you are a target competition shooter who does not worry about jamming a bullet:
1. .010 into (touching) the lands (jam) 6 rounds
2. .040 off the lands (jump) 6 rounds
3. .080 off the lands (jump) 6 rounds
4. .120 off the lands (jump) 6 rounds

Load 24 rounds at the following COAL if you are a hunter (pulling a bullet out of the case with your rifling while in the field can be a hunt ending event which must be avoided) or a competition shooter who worries about pulling a bullet during a match:
1. .010 off the lands (jump) 6 rounds
2. .050 off the lands (jump) 6 rounds
3. .090 off the lands (jump) 6 rounds
4. .130 off the lands (jump) 6 rounds

Shoot 2 (separate) 3 shot groups in fair conditions to see how they group. The remarkable reality of this test is that one of these 4 COALs will outperform the other three by a considerable margin. Once you know which one of these 4 COAL shoots best then you can tweak the COAL +/- .002 or .005. Taking the time to set this test up will pay off when you find that your rifle is capable of shooting the VLD bullets very well (even at 100 yards)

Is this how (or variations) what others use when fine tuning coal?

 

[hounddawg]

I like the Berger method for rough tuning COAL. You can load the depth test bullets, pressure test bullets, and charge test bullets at home just leave those at maximum length and use a Lee handloader to seat the pre loaded charge test bullets to the best COAL at the range. Saves the hassle of powder measuring at the range

I sometimes do a second tune on COAL working my way in and out from the best in .003 incs to fine tune. You can tune groups horizontally and vertically with practice

 

[USSR]

oley55,

I had a hard and fast rule when loading for 1,000 yard F Class Competition: Never set your COAL to less than 0.010" off the lands. Reason: Even with Sierra MatchKing bullets the ogive variances will put some of the bullets off the lands and some into the lands due to the bullets coming off different machines at the factory. Not good for accuracy. So, I would usually set my COAL for 0.012" off the lands or 0.020" into the lands and call it good.

Don

 

[cw308]

I read that before , never liked the idea of going .120 or .130 off the lands . I would think it could cause pressure problems if your powder charge is at the top of the scale . Starting from a jam .001 isn't a jam a jam whether .001 or .010 What I did is find my zero to the lands then jammed .002 then zero then jump .002 to .020 with a powder charge mid range on the powder scale . Once I found the best consistent length I raised or lowered the powder charge . What worked best for me was a charge at the lowest end of the csale with a .002 jump . Keep in mind I'm only shooting from the bench at 200 yards always . For hunting or shooting different distances or long , powder charge should be higher . I don't own a chronograph , some of my friends just go by the numbers , I just go what groups the best by trial and error . Hope I Helped in some way .

Chris

 

[oley55]

COAL Ogive measuring results

last night and again today I have been re-remeasuring ogive COAL on my Savage 10 FCP using two methods; the Hornady Lock n Load COAL tool and fire formed brass close bolt to seat bullet against the lands. In the course of this exercise I have encountered two issues.

1. The throat/jump to lands portion of my chamber is quite snug on the bullet (see attached diagram below). To the point when initially measuring with the Hornady coal tool, I was getting really short measurements (2.1050"). Basically the bullet would not move forward to touch the lands without a lot of pressure. So I thought maybe I have some carbon ringing in there. So I plugged the chamber at the shoulder and soaked the throat/lands in Slick 2000 Carbon Remover for 30 minutes, then made a few twists with a brass bore brush up to and barely touching the lands. Then a through cleaning and tried again. It helped, but the jump area is still tight on the bullet as shown by the scuff marks shown in attachment 2. The top/left bullet is in the Hornady COAL tool and the bottom/right one is in my fire formed brass.

Is this bullet scuffing abnormal??

2. I really had trouble getting repeatable measurements using the Hornady tool. I applied a good bit of forward pressure on the tube that holds the case and would rotate the whole assembly clockwise to coax the case to the center of the chamber shoulder before pushing the bullet forward (last pic shows rub marks on the shoulder). I also used a 1/4" brass rod covered in heat-shrink to protect the crown/rifling and worked the bullet in and out with pressure from both directions feeling for the point of lands contact. Being not so confident with non-repeatable measurements, I used the close bolt method found here at Berger bullets: http://www.bergerbullets.com/effect...coal-and-cartridge-base-to-ogive-cbto-part-2/ On account of the tight jump area, I deviated from their suggestion and used fire formed brass that had been neck turned and bushing neck sized, I then opened up the neck with a my K&M neck sizing mandrel. This gave me a fairly firm bullet hold (beyond bare finger pressure). I slipped the case under the ejector and guided the round into the chamber, seating the bullet against the lands until closing the bolt. I did this several times and got repeated results that were predictably different form the Hornady tool's brass.

Hornady tool average= 2.2350" vs LC F/Formed consistent=2.2390". (Ogive measurements). That's a difference of .0040"

Then I measured the Hornady brass and compared it against my fire formed brass, and predictably found the Hornady brass to be shorter as measured using a Hornady comparator gauge.

Hornady tool brass=1.6215" vs LC F/F brass=1.6235", for a difference of .0020".

Taking into account the .0020" difference in case lengths, my final coal ogive measurements are still off by another 0020". Since the F/F case close bolt method gave repeated results, I think that is the measurement I should be working off. But then again, perhaps the force needed to seat the bullet against the lands is actually a jammed measurement.??

 

[RC20]

I have only found that the Hornady tool is a guide, not a given.

I think its the plastic and all the give. My brother machined some (not for sale) and gave one to me. That is much more accurate.

At best the Plastic tool was .020 short (not a given) short of true.

I too find the lands with the metal tool for general, then refine that with a SIZED case with a long seated bullet.

Why? It does not slip. The issue I do run into with long shank bullets is they will stick if the setup is too long. So when doing that, I very gently close the bolt and when (if) I hit resistance and it sticks, I tap the handle with a plastic screw driver handle gently and they come back out.

You can do the whole find the lands thing with the bullet in a sized case. Seat it long and gently close the bolt. As long as not hard you can tap it out with the plastic handle. Just set it .010 shorter each time (or more if its way out) and you will be very close on the one that does close. Then use it or add another .010 longer for safe. Note the close reading for reference.

Mostly they don't move but I mike them with the Ogive compactor when I get them back out to be sure.

Per above, I have found that .010 can have a stray that is long Ogive.

I usually don't go closer than .015, a stuck bullet is nasty in that you need to tap it out with a rod, you can pull it out with extraction and you have powder granules all over the place.

Each mfg type bullet will be different (Match, ELD, hunting etc all have their own shapes. )

How the target types can jam them and no issues I don;t know or they ignore the issues maybe.

Granted I am not going to ever be David Tubb.

 

[cw308]

I use the close bolt method , takes some time but I find it the most accurate and repeatable .

 

[reynolds357]

Who knows? Different rifles like different stuff. Ain't worth a doodle for a hunting rifle, but my best shooting 1k rifle likes it the way many bench rest shooters did it 60 years ago. Inside ream necks to almost no neck tension, stick enough of the bullet in the case that it probably won't fall out, let the lands seat the bullet as I slowly close the bolt.

 

[cw308]

357
Some of my friends soft seat but you take the chance of powder spilling all over your action if you have to open your bolt an the bullet sticks in the lands . Not really the same as finding where your lands start and knowing that measurement .

 

[reynolds357]

Some of my friends soft seat but you take the chance of powder spilling all over your action if you have to open your bolt an the bullet sticks in the lands . Not really the same as finding where your lands start and knowing that measurement.

Finding the measurement is easy. I Never spill powder.

 

[cw308]

oley55
After looking at your posted bullets , what you could try is measuer from the base of your posted cases to the start of the scuff on the bullet . Seat a bullet to that ogive measurement or subtract from OAL and see how it chambers , smoke or use a marker on the bullet to see if your touching the lands.

 

[RC20]

Oley 55:

You last post went in before mine did.

The left one is not normal scuffing . Did it stick or did it change COAL when you pulled it out.

The right one is just touching the lands, maybe too hard maybe not (if it sticks then too much of course). .020 less would be safe, you might get it to .010.

What bullets are you using?

As noted, one issue is you get close and bump along then have to unload for a cease fire and you find its stuck. The Ogive variation can do that.

As I am not bench rest class, I don't mess with that.

 

[hounddawg]

I alternate between the closed bolt and Hornady tool and get pretty consistent results between the two. I tap the bullet a few times with the brass cable to make sure it is all the way in, do three to five bullets. Most difference I ever see is .001 - .003 base to ogive with Sierras or Berger's and the outliers are few and far in between.

@RC20 if ypou want a metal tapper get the curved model. I have a ten years old one and it is all anodized aluminum and with a brass cable and brass stopnut. No plastic at all. Just like the ones in these pics

https://www.hornady.com/reloading/p...tools-and-gauges/oal-gauges-modified-cases#!/

edit - and on the Berger test you don't have to do .100 etc to lands, I like .075, .050, .025, and .005 for a rough seating test and do 5 rounds per depth.

 

[F. Guffey]

adjusting coal to the lands "methods"

I want to know where the lands are located; I also want my bullets to have 'that jump', and then there is the running start. When my bullet hits the lands I want the bullet to have that running start.

F. Guffey

 

[oley55]

RC,

the one on the left is more scuffed because using the rod through the barrel and the Hornady COAL tool, I gently seesawed it in and out feeling for the point where the bullet stopped against the lands. Having measured many times, no telling how many times it went into and out of the throat/jump area. The one on the right has less scuffing because I was doing the close bolt method, so it only went in and out 4 times.

all bullets stuck using the Hornady tool because the neck is really loose and the bullet is just laying in the case. Did not have any stick using the "close bolt" in F/F brass. I think I will do the close bolt again and feel with the brass rod against the bullet tip to try and feel if the bullet is being pulled back out any as the case is withdrawn.

Hornady 168gr, HPBT Match bullets

All that aside, are throats normally that snug?

 

[oley55]

F. Guffy,

Yea adjust to lands may not be the best choice of words. Adjust from the lands may be better.

 

[Unclenick]

That extra 0.020" is about the length of a typical freebore. I think the chamber reamer may have been a little worn and cut that freebore too snug. If so, it can be fixed with a throating reamer. I have had bullets catch a little due to misalignment in the Hornady tool (though mine is the original Stoney Point version, and has a metal rather than a plastic bullet ram), but jiggling has always got the bullet to find its way forward. If this is a chronic problem, size the upper half to two-thirds of the neck in die bushings until it just lets the bullet fall through with maybe 0.001" clearance. Or you could size the top half of the neck in a regular sizing die with the expander removed, then use a turning mandrel to get it back out just a thousandth over bullet size, if you have one that will do that for you. The idea here is to align the bullet straighter going in, but without adding friction. Doing it only to half to two-thirds of the way down from the mouth of the neck will allow the remaining fat part of the neck help center the case in the chamber.

Regarding the length of the measurement, get the case comparator inserts for the Hornady caliper adapter. Measure the Hornady OAL gauge case with it write down the number it gives you. Then measure with the bullet comparator. Subtract one number from the other (which from which doesn't matter as long as you are consistent). This will be a number that makes no sense by itself, but if you do the same thing with your cases when you are checking your bullet seating adjustment progress, you will find that when the numbers match you are seating to zero bullet jump with rimless bottleneck cases and you can then adjust however many thousandths deeper you want it to go to set bullet jump. That is because you are setting how far the ogive of the bullet is from the case shoulder, and since the shoulder is what the case headspaces against, it is what actually determines how far the bullet sticks into the throat of the bore, not the bullet ogive location with respect to the head of the cartridge.

As to the Berger method, their recommended 0.030" to 0.040" are intended for the long ogive VLD bullet shape, as you noted. I like the method but prefer to use 0.020" with shorter ogive bullets as they don't have to set back as far to allow a given amount of additional gas bypass between the time the neck lets go of the bullet and the time it finds the throat.

 

[F. Guffey]

Yea adjust to lands may not be the best choice of words. Adjust from the lands may be better.

That would depend on where you are standing. I understand that makes no sense to you and that confuses everyone else. Reminds me of the TV series 'WELCOME BACK COTTA'. Vinny was struggling to keep up when he came up with one of the greatest reloading responses of all time; He said; "I am so confused!".

You say tomatter and I understand but when you say 'from' I am reminded of a trip I did not take because I could not understand how the train could arrive before it left. So instead of purchasing a ticket I ask if they would allow me to stand back and watch that train take off.

A man built 4 magnificent with a wildcat 7mm chamber that was similar to the 7MM Gibbs. He made the chamber reamer, did all of the stock work and the bluing etc.. When finished one of the rifles came back, it just did not shoot, n groups just patterns.

The rifle did some traveling from shop to shop and finally got a bore scope stuck up the chamber; nothing but teeth gnashing and the wringing of hands and then? He called me, the builder was at wits end but just before that he got onto the Internet and started to tell me what they suggested.

I thought, when he called he wanted to know what was wrong with the rifle, I was not interested in the long boring story about his effort in determining the problem with the rifle so he asked me where would I start. I started by telling him where I would start and how I would go about testing the rifle.

His thinking? If it was that easy anyone should be able to 'do it' so he took the Internets advise and it did not take him long to determine something did not make sense.

So? He called again. I asked him to bring all of that stuff he found on the internet, with the rifle, reamer and fired cases over and then we would get started.

Adjust to the lands or from the lands. I did not start at the lands because I did not know where they started; all of the smiths that checked the rifle had no clue where the lands started. I found the lands by determining the distance to the lands from the bolt face. I sized the neck of his fire formed cases. I used all of the bullet hold I could get. I pushed the bullet out of the case until it contacted the lands. By that time the bullet had come out of the case and skidded through the throat .300"+ before the bullet contacted the throat.

I had access to over 250 chamber reamers, there was no reamer available that would allow me to ream the chamber to any 7MM chamber like a Weatherby and if I found one the magazine and receiver would be too short.

Fixing the rifle was not my problem, the tools I used to check his chamber dimensions were home made, I can measure the distance from the beginning of the rifling to the bolt face with a home made tool, I choose to make a tool that measure from the bolt face to the rifling instead, Instead of the bolt face I could use the shoulder to the beginning of the rifling or I could use 'the datum' or I could transfer the measurements from the chamber to the seating die and from there I could transfer the dimensions to another datum based tool: problem we have too many Vinnie's on the Internet.

F. Guffey

 

[cw308]

Ordered a go gauge to check the chamber with a stripped bolt on my Rem.700 308 , the 1.630 go gauge and a .002 shim my bolt closed with the slightest resistance . From there I full sized my cases to 1.631 to 1.630 no more or less . Then I did the same using a sized case seating the bullet long and lower slightly in the die untill it closed the bolt without resistance to find the rifling , from there I can jump or jam , what ever works best . My rifle likes a .002 jump using a Sierra 168 MK . Takes alittle time but works well for me , I check my measurements with the RCBS Precision Mic.

 

[USSR]

cw308,

Some advice from a long time 1,000 yard shooter: First, don't use the 168SMK for anything beyond 600 yards. Then, use low neck tension (0.001") with good brass (Lapua). Lastly, if you jam, drop your powder charge back 1 full grain.

Don