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rc.saul
Guest
Im trying to figure the perfect seating depth, but not sure how to accurately measure where the lands start. Help, Im new to reloading.
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Dennis Sorensen
Guest
The easiest for a beginner is trial and error... seat a bullet in a fully sized case and leave it out what appears a bit long...
...slowly close the bolt on it until you feel resistance... if the bolt is out quite a ways, seat the bullet a bit deeper... eventually you will be able to close the bolt on it and when you inspect the bullet you will see shiny marks where it has hit the rifling...
... polish the bullet with a little fine steel wool and smoke it with a candle or what ever will lay some soot on it... try it in the rifle again... the marks should show up on the soot...
There are many other ways as you will soon find out...
...slowly close the bolt on it until you feel resistance... if the bolt is out quite a ways, seat the bullet a bit deeper... eventually you will be able to close the bolt on it and when you inspect the bullet you will see shiny marks where it has hit the rifling...
... polish the bullet with a little fine steel wool and smoke it with a candle or what ever will lay some soot on it... try it in the rifle again... the marks should show up on the soot...
There are many other ways as you will soon find out...
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Larry Elliott
Guest
Another way is to seat the bullet long and blacken it with a Sharpie or other marker. I find it's easier to see the rifling marks if they're copper against black. It might be necessary to slit the case neck with a cutoff wheel in a Dremel and give it a squeeze with your fingers to hold the bullet.
It's probably best to repeat this a few times to get an accurate measurement if it's a new process, or even if you've done it a few times.
It's probably best to repeat this a few times to get an accurate measurement if it's a new process, or even if you've done it a few times.
JerrySharrett
Senile Member
One minor thing to keep in mind, and this is a picky detail, when you are "just touching" the lands there will be no mark on the bullet!! Just touching does not make a mark.
Like Dennis says, spin the bullet nose in a ball of steel wool held in your fingers. Then the first faint mark you begin to see, the bullet is getting into the lands.
The bottom line on bullet seating, for benchrest chambers, don't jam too tight to where the bullet will pull out of the case if you have to unload. Then as to where it needs to be, let the gun tell you. Seat at first to where you see a mark (one for each rifleing) that is about 1/4th as high as it is wide. Then tune with the powder to get the best groups. Then, and many new br shooters miss this important step, move the bullet in and out 0.003"-0.005" for about 0.020" and fine tune based on where the group is the smallest.
Start with 2-shot groups. If, in good conditions, even without flags, if, the first two don't go through the same hole, you do not have tune. A group never gets any smaller after the second shot.
Like Dennis says, spin the bullet nose in a ball of steel wool held in your fingers. Then the first faint mark you begin to see, the bullet is getting into the lands.
The bottom line on bullet seating, for benchrest chambers, don't jam too tight to where the bullet will pull out of the case if you have to unload. Then as to where it needs to be, let the gun tell you. Seat at first to where you see a mark (one for each rifleing) that is about 1/4th as high as it is wide. Then tune with the powder to get the best groups. Then, and many new br shooters miss this important step, move the bullet in and out 0.003"-0.005" for about 0.020" and fine tune based on where the group is the smallest.
Start with 2-shot groups. If, in good conditions, even without flags, if, the first two don't go through the same hole, you do not have tune. A group never gets any smaller after the second shot.
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chillippr
Guest
Larry Elliott +1
There is some good advice in this thread, and it could lead you to wildly wrong conclusions & frustration.
First point is Jerry's. A bullet "just touching" does not leave a mark. Absolutely true. And you see people all over the internet, and even in print, talking about .005 in (jam) or .005 out (jump). Don't take their numbers literally, you don't really know where they started.
What you are really interested in is establishing a reference point that makes sense to you, and you can use over and over, for all your reloading work. .005 differences do count. But if you're getting numbers off the internet & trying to follow them, there is a fair chance you can go astray.
Personally, I use the point when I can just see a set of land marks on a bullet as my "just touching" point. It isn't, of course, but I can see it. Further, if I didn't polish the bullet with green "Scotch brite" and didn't use a 8X loupe for viewing, I might wind up with different a different spot. So I do both of those things.
If you use how long the marks are -- as I do -- built in to the assumption is a 1.5 degree leade in the chamber, and probably bullets made on J-4 jackets. I do have a couple rifles with 2-degree leades, and I have to remember to pay attention. Same thing with a Shilen Ratchet-rifled barrel, where the land profile is different.
The important point here is for you to establish a way of getting a reference mark that makes sense to you, and you can repeat.
Another note: When jamming bullets .005 matters, sometimes a lot. It can mater with short jumps, too. But when you jump a lot, as is getting fashionable with VLD bullets in the long-range game, it usually matters less. I doubt many could shoot the difference between, say, .075 off and .080 off. Remember too that for some chamberings, the throat will advance; with big chamberings, that advance can be both quick and a lot.
Finally, the two-shot groups bit. All true. It will never get better than the first two. But it can also mislead you. I'd bet even Jerry, if he had to do his testing at Rockingham, might consider three or four shots. It comes down to how much do you trust your ability, and the range you're working on. And a large part of trusting your ability is how much you can rule out. For example, if you are testing a PPC, your powder choices are what, two or three? That's it. And bullet choices, by both style and pocket book, are also two or three.
Move to long-range with big cases, and both powder and bullet choices seem to open up. Why? Because we don't have 30 years of developing one chambering with a very small range of bullets (e.g., the 6 PPC with bullets from 62 to 68 grains).
Good luck, just remember to establish procedures that you can apply consistently, and to take what's printed on the internet as "more or less" rather than exact.
First point is Jerry's. A bullet "just touching" does not leave a mark. Absolutely true. And you see people all over the internet, and even in print, talking about .005 in (jam) or .005 out (jump). Don't take their numbers literally, you don't really know where they started.
What you are really interested in is establishing a reference point that makes sense to you, and you can use over and over, for all your reloading work. .005 differences do count. But if you're getting numbers off the internet & trying to follow them, there is a fair chance you can go astray.
Personally, I use the point when I can just see a set of land marks on a bullet as my "just touching" point. It isn't, of course, but I can see it. Further, if I didn't polish the bullet with green "Scotch brite" and didn't use a 8X loupe for viewing, I might wind up with different a different spot. So I do both of those things.
If you use how long the marks are -- as I do -- built in to the assumption is a 1.5 degree leade in the chamber, and probably bullets made on J-4 jackets. I do have a couple rifles with 2-degree leades, and I have to remember to pay attention. Same thing with a Shilen Ratchet-rifled barrel, where the land profile is different.
The important point here is for you to establish a way of getting a reference mark that makes sense to you, and you can repeat.
Another note: When jamming bullets .005 matters, sometimes a lot. It can mater with short jumps, too. But when you jump a lot, as is getting fashionable with VLD bullets in the long-range game, it usually matters less. I doubt many could shoot the difference between, say, .075 off and .080 off. Remember too that for some chamberings, the throat will advance; with big chamberings, that advance can be both quick and a lot.
Finally, the two-shot groups bit. All true. It will never get better than the first two. But it can also mislead you. I'd bet even Jerry, if he had to do his testing at Rockingham, might consider three or four shots. It comes down to how much do you trust your ability, and the range you're working on. And a large part of trusting your ability is how much you can rule out. For example, if you are testing a PPC, your powder choices are what, two or three? That's it. And bullet choices, by both style and pocket book, are also two or three.
Move to long-range with big cases, and both powder and bullet choices seem to open up. Why? Because we don't have 30 years of developing one chambering with a very small range of bullets (e.g., the 6 PPC with bullets from 62 to 68 grains).
Good luck, just remember to establish procedures that you can apply consistently, and to take what's printed on the internet as "more or less" rather than exact.
Measurements
Everyones measurement, even on the same rifle, as to where the lands start will be different.
The good news is that the true measurement is not what you are after.
You are just finding a place to start.
I use 0000 steel wool on the bullet and look for a square mark on the bullet when I seat the cartridge. This mark is as long as it is wide. Very easy for me to see. This is where I start. I DID NOT SAY THIS IS WHERE I START SHOOTING.
Something to remember is that when jamming to make the mark, the bullet may also move back into the case, so the setting on your setting die will need to be adjusted to equal your final true measurement at the ogive or ojive depending on your location in the USA.
Not all bullets like to be in close. I have a .243 shooting very small groups using Barnes TXS and it did not shoot worth a darn until I was 0.100 off the lands.
Everyones measurement, even on the same rifle, as to where the lands start will be different.
The good news is that the true measurement is not what you are after.
You are just finding a place to start.
I use 0000 steel wool on the bullet and look for a square mark on the bullet when I seat the cartridge. This mark is as long as it is wide. Very easy for me to see. This is where I start. I DID NOT SAY THIS IS WHERE I START SHOOTING.
Something to remember is that when jamming to make the mark, the bullet may also move back into the case, so the setting on your setting die will need to be adjusted to equal your final true measurement at the ogive or ojive depending on your location in the USA.
Not all bullets like to be in close. I have a .243 shooting very small groups using Barnes TXS and it did not shoot worth a darn until I was 0.100 off the lands.
JerrySharrett
Senile Member
Charles E is spot-on, 2-shot croups can mislead you, so for sure, don't make your final decision based on 2-shot groups. The point I was making here is that if the first 2 don't go in the same hole, (repeat this test 2-3 times before continuing) you are still not tuned good enough.
To new shooters with benchrest quality guns, "covering them with a dime" doesn't cut it. You can do a search on the 600/1000 yard forum to see pictures of a group shot last year by John Lewis at 600 yards, where a dime covered all 5 shots. And John was shooting a 308!!!
http://www.benchrest.com/forums/showthread.php?t=51714&highlight=Record
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I agree with Jerry, it is just this caveat: My home range is Rockingham Gun Club. It isn't Jerry's home range, but he knows it well. Typical wind is a fishtailing 11:00 to 1:00 o'clock. There is a great big honking hole about 50-70 yards out. You need a 18-foot tall windflag pole. I've seen windflag tails point straight up. Vertical at Rockingham isn't "occasional," and I can't always read it. Neither, I'm told, can Tony Boyer. Roy Darnell obviously can. Dunno about Jerry.
This matters for tuning a rifle. If I'm testing loads, at Rockingham, I shoot 4-shot groups. If it is four bunched into less than .2 with one popped out the top, I don't conclude I'm out of tune. And that high one might have been the second shot . . .
Point is, adapt your technique to your known skills and range. I, for one, am in between. There are ranges where I trust how two shots print, and ranges where I don't.
This matters for tuning a rifle. If I'm testing loads, at Rockingham, I shoot 4-shot groups. If it is four bunched into less than .2 with one popped out the top, I don't conclude I'm out of tune. And that high one might have been the second shot . . .
Point is, adapt your technique to your known skills and range. I, for one, am in between. There are ranges where I trust how two shots print, and ranges where I don't.