TassieTiger wrote:How come, I can set my die up for a COAL of say 79.00mm and then without changing a single thing, on the die or on the press or anything - I can get 78.70 to say 79.10 to 78.60 to 79.00 ? This is with the cases exactly the same lenght - each one measured with verniers and cut to length.
Even with brand new Lapua brass - which is quite remarkable, I end up with different oals.
Is this difference in the ogive of the projectile ?
I have noticed that my Hornady press, has a slight bit of movement in the collet and in the press itself it seems to be a tiny amount of movement and I know we are talking very small numbers but when trying to get the COAL exactly perfect, its frustrating to chase numbers back and forth...
Cheers. Tas.
pomemax wrote:'no doubt about it stix, your a card '(NEED DEALING with )
straightshooter wrote:TassieTiger wrote:How come, I can set my die up for a COAL of say 79.00mm and then without changing a single thing, on the die or on the press or anything - I can get 78.70 to say 79.10 to 78.60 to 79.00 ? This is with the cases exactly the same lenght - each one measured with verniers and cut to length.
Even with brand new Lapua brass - which is quite remarkable, I end up with different oals.
Is this difference in the ogive of the projectile ?
I have noticed that my Hornady press, has a slight bit of movement in the collet and in the press itself it seems to be a tiny amount of movement and I know we are talking very small numbers but when trying to get the COAL exactly perfect, its frustrating to chase numbers back and forth...
Cheers. Tas.
As others have pointed out there is some variation in ogive position even in high quality projectiles.
You need to have a reliable method of establishing oal when the projectile's ogive starts into the lands.
Method 1 is to size the neck of an empty case just enough so that the projectile can be seated long and it is firmly held but not so tight that it can't be moved. Chamber the test case and force the bolt closed. Then remove the case. Measure oal.
Now this is the most important step. Use that same particular projectile to set up your seating die for your desired projectile throat relationship.
Method 2 is quicker and simpler. Use a Stoney Point Chamber All gauge for establishing your maximum oal. Hornady now make a copy at a reasonable price. Measure your resulting oal.
And again the most important step is to use that exact same projectile to set up your seating die.
From there on you can ignore the minor variations in COAL particularly so if your seating stem makes contact with your projectile's ogive near to it's maximum diameter and not near the tip.
TassieTiger wrote:Even when I set up my max / demo cartridge- I’d place it into my press to set up die and I’d screw die down to touch nose and it would creep projectile in .5mm or similar as when I’m tightening the screw, I can’t feel it until it’s touching and this touch on a loose case...hmmm...so another method needs to be found for me...which is why I’ve bought the hornady comparator. Hopefully, I don’t end up weighing individual parts, turning necks, triple measuring everything, etc like Brett...because my family WILL divorce me.
straightshooter wrote:Method 1 is to size the neck of an empty case just enough so that the projectile can be seated long and it is firmly held but not so tight that it can't be moved. Chamber the test case and force the bolt closed. Then remove the case. Measure oal.
marksman wrote:if your seating stem is pushing the bullet from the tip it needs to be drilled out so that it only connects at the ogive to give a true reading
maybe this is the problem
Bretts advise is good advise for solving your problem
Oldbloke wrote:"when you measure max oal you do it with your firing pin removed and with a fired in"
Why? How would the firing pin interfere if it's cocked?
No safety reason, it's an empty case.
marksman wrote:to check if your seating stem is right for your projectile shape take it out and try a projectile in it if it does not touch at the ogive it is hitting the point
bladeracer wrote:marksman wrote:to check if your seating stem is right for your projectile shape take it out and try a projectile in it if it does not touch at the ogive it is hitting the point
Mine touch at different points along the ogive depending on the shape of the bullet. None of my dies seat on the point of the bullet, or at point where the ogive meets the rifling. It's generally about halfway between the two points.