How do you really measure distance to the lands?

[Jason]

What tools do I need and how to I use them to reliably measure the real distance to the lands for loading my HP rounds? My version of making a dummy round and just adjusting my seating die in until I don't see marks on the bullets anymore isn't exactly precise. I have calipers and have the bump gauge attachment for 6.5mm, but don't really have a way of measure the chamber itself to know what length to seat the bullets to.

[stsbuyer]

Jason,

You need to go back to Sinclair again. Take a look at this and a couple of others that they have. I use the one that Hornaday sell which used to be Stoney Point.

http://www.sinclairintl.com/product/680 ... -Tools-OAL

http://www.sinclairintl.com/product/104 ... -Tools-OAL

[Innocent]

Jason,
Beware there is that Sinclair word again!!!!

BTW Christmas is coming.

Innocent

[Joe Maisto]

Jason,
What all of us do in the "group" shooting world is as follows. It is the only accurate way . Forget the "stoney point" gauge, or any other.
To begin with, part of what you are doing is correct. A dummy round will tell you what you need to know. We prefer to "smoke" the bullet with several stick matches. You'll need to do this several times, paying attention to the rifleing marks on your bullet. I choose to have the marks only as wide as they are long, ( more or less a square mark now.)
In that way, you won't jam a bullet into the lands which can and will pull your bullet out of the case. (We been there), and now you have powder in the action.

Understand that all barrels are not created equal. Some like jump, some not. I prefer .004-.005 off myself. Furthermore, as your throat wears, you will need to make a change, at least in the game we shoot, which is trying to put 5 rnds. into the exact same hole the first one went into.

[Joe Maisto]

I have an original stoney point some one can have for $8.00 plus probably around $5.50 shipping. (depends where to)
The general consensus amoung us in group shooting is you never get the same reading twice. Each time you have to pick up another tool and measure simply increases your chances of not really finding out.

[Jim Beckley]

I use the Stoney Point/Hornady tool and then, I measure the overall length from a comparator also made by the same company. It measures off the side of the bullet or the ogive rather from the top of the bullet where there could be my guess as much as 10-20 thousands difference. I'll usually measure 3-5 times get a average and then subtract 10 thousands from it and that is my OAL. The case that you buy to help measure the OAL wasn't fired in your chamber so what ever difference in the two head spaces will come into play, but it's usually not much. Your best bet is to drill and tap one of your own cases. Like someone else stated that the lands are normally the first to go, so if you are going to follow the lands you will have to remeasure after about 300-500 rounds. Just my 2 cents!

[Jason]

We prefer to "smoke" the bullet with several stick matches.

Why smoke the bullet instead of just using a Sharpie marker or something?

[Joe Maisto]

Some do use a sharpie. Some shine the bullet with 0000 steel wool. I have done both. I prefer the smoke. Just seems to show up better. Probably a hang over from the old Marine Corps days of smoking the front sight on an M1.

[kevinbear]

Ditto;The boys in the Houston warehouse proved that this was correct and published it in Precision Shooting in the eighties. Square marks on the bullets.
[quote="Joe Maisto"]Jason,
What all of us do in the "group" shooting world is as follows. It is the only accurate way . Forget the "stoney point" gauge, or any other.
To begin with, part of what you are doing is correct. A dummy round will tell you what you need to know. We prefer to "smoke" the bullet with several stick matches. You'll need to do this several times, paying attention to the rifleing marks on your bullet. I choose to have the marks only as wide as they are long, ( more or less a square mark now.)
In that way, you won't jam a bullet into the lands which can and will pull your bullet out of the case. (We been there), and now you have powder in the action.

Understand that all barrels are not created equal. Some like jump, some not. I prefer .004-.005 off myself. Furthermore, as your throat wears, you will need to make a change, at least in the game we shoot, which is trying to put 5 rnds. into the exact same hole the first one went into.[/quote]

[Jason]

I don't understand the "square marks" thing. My plan was to gradually adjust the seater (Forster ultra micrometer seater) down to the 1/1000 where I no longer saw any marks on the bullet at all, then seat the bullet .005" deeper, which is what I thought was meant by .005" off the lands. Can one of you guys explain the square marks things a little more thoroughly? Do you mean that you have it touching the lands enough to make square marks on the bullets when chambered and then extracting the loaded rounds?

[Joe Maisto]

Jason,
I'll try to be a bit more clear. To begin with, use an UNPRIMED case fired in YOUR chamber, resize it, seat a bullet LONGER than normal, slip it into your action, and s-l-o-w-l-y work the bolt forward. If it does not close as normal, remove the empty cartridge and examine the land marks on the bullet. They will be elongated . Adjust the bullet seating stem down .005 or so , smoke the bullet again, repeat the chambering process. It may require several times doing this.
Eventually, upon examination, you will find that the "marks" on your bullet are ONLY as wide as they are long.
To put it another way, you will now be JUST touching your lands, which is usually desireable. ( but not always)
As I said earlier, some barrels like a little jump.

Another IMPORTANT NOTE ...If you change bullets, you must go through this procedure again. The Ogive is almost always differant with differant manufacturers.

On another note, you would do well in using a Redding full length SMB (small base die) with neck bushings. You can change the neck tension by changing bushings to your likes, ( and your rifles).

Hope this helps.

[Jason]

Thanks, Joe. That does explain it well. Now for the next question. Why use a full length SBD die? I've heard of only neck sizing with those Redding bushing neck dies (which is what I was doing with borrowed dies before I bought my own) and barely bumping shoulders and neck sizing using Redding FL bushing dies. It sounds like a small base die would definitely resize the whole case every time, removing the benefits of having it already fired in my rifle's chamber.

[Joe Maisto]

The Redding die I mentioned is more than a full length die. It is also used as a shoulder bump die in addition to having the neck bushings of your choice. I have a $100. FL die I had cut and it won't size a case from another barrel
( that I have) which was chambered by someone else, because there is a slight differance in chambers. The Redding die took care of that problem. You understand...I ( some of us ) use a snug chamber, as well as a turned neck within
.000015, (1 1/2 thou.)
I finally bought my own reamer which is what many do. If you are using a factory rifle, it doesn't matter then.
If one of your sized cases fits into everybody elses rifle, that tells me they allowed plenty of room to begin with.

In my shooting, we find the correct shoulder bump by removing the firing pin assembly from the bolt, placing a sized case into the action, push the bolt on our single shot rifles forward, and carefully and s-l-o-w-l-y ease the bolt handle down.
If it "falls" with no effort, the case has been bumped too far. Probably only .0001 or .0002, but enough whereby there will be some play in the forward motion when firing. We stay away from any kind of play in that regard, and try to go for a bolt closing in the downward motion...with just a slight "feel" to it. Now we have achieved the best possible marriage of case and chamber.

On new brass, I can get away with neck sizeing only ......with my Wilson hand dies used with my arbor press for about 4 firings. When they start to grow a bit, it's time for a little bump.

[Jerry G]

I have gotten consistent results with the Sinclair. The real trick is to know how much jump to use to get the best accurcy. It is a lot of work for fractions of a minute. I'm not convenced that it is required for our crazy game.

[Jim Beckley]

I was thinking the same thing, Jerry. If I was a new shooter, I would probably spend my time getting my best position and then trying to get my hold as tight as possible, rather than spend it getting my ammo to group ten thousands tighter!