bullet seating depth?

[Elk whack master]

I am getting two different lengths from two different bullets. You do this for each size / style bullet , right. What I see on you tube it seam like that you do this once and that's your length for all your loads. My 180 accubonds are 2.905 and the 220 partions are 2.924. I am using a hornday o.a.l. gauge.

[jamesjett]

Could be...best to measure from the ogive.  You can actually get different measurements from the same type of bullet due to variances in the tips during the manufacturing process.

[lokidog]

Different bullets have different ogives (the curve from the side of the bullet to the tip.  It is not the tip length that you need to worry about, other than fitting into your magazine, but how far off the lands the ogive is when the bullet is in the chamber.  Bullets of different weights will be different lengths.  If you have a bullet seater that contatacts your bullet away from the tip, it should place the ogive in about the same place (?) but a heavier bullet will be longer and have less of a curve and probably a longer tip.

Just a guess.

[Heredoggydoggy]

The bullet seater plug in your die will seat different bullets differently because of their shape.  The seater is machined to push on the sides of the bullet so as not to damage the point.  When you seat a different bullet you need to adjust the seater to counterract the different shape and keep the same COAL.

[Elk whack master]

I'm using a bullet comparator, so I am measuring from the ogive. 

[Feanix]

Like HDD said, different bullets, even from the same manufacturer can and will have different ogives, so you will have to adjust your seater for each one to keep the same COAL and jump to lands. I've even had different runs of the same bullet measure differently and had to reset also.

[lokidog]

I'm using a bullet comparator, so I am measuring from the ogive.

That's kind of odd.  Is it a compressed load with the heavier bullet?  Maybe the compressed powder is pushing the bullet back out a bit if it is.

[Heredoggydoggy]

I'm using a bullet comparator, so I am measuring from the ogive.

COAL is exactly that--the TOTAL length, base to tip.  Never used a comparator, so I don't know much about them, but if they measure from the ogive, that will not give you COAL.  They will only give you distance from the ogive to the rifling at the throat, which I think has to be determined by another method first, depending on the chamber throat.  Do not assume that they are all the same, because they are NOT!

[Elk whack master]

I haven't loaded anything yet. Just figuring out the lenght to the rifling  so I can get the desired .020 jump to the lands. Then I will make adjustments for coal and make sure they fit in the mag. I just noticed the difference between the two. If the tips are irregular you get different coal. accubond tips are difficult to keep all the same. Just trying to make that perfect bullet to get tighter groups. If you measure to the tips then some will have to jump more than others.

[Heredoggydoggy]

I think Hornady makes a tool that holds a case with a bullet lightly seated that you push into the chamber and the rifling pushes the bullet into the case, and then you can adjust the seating depth for the required "jump" using that measurement.  Of course, if your gun is magazine-fed, that will determine COAL, unless you hand chamber the first shot...

[Elk whack master]

I am using the hornday O.A.L. gauge  and a hornday bullet comparator to get the distance from the ogive.  Doing so I noticed the difference between the two bullets and wanted to know if that was normal.

[Curly]

I am using the hornday O.A.L. gauge  and a hornday bullet comparator to get the distance from the ogive.  Doing so I noticed the difference between the two bullets and wanted to know if that was normal.

Yep.  That is normal. 

[jamesjett]

I haven't loaded anything yet. Just figuring out the lenght to the rifling  so I can get the desired .020 jump to the lands. Then I will make adjustments for coal and make sure they fit in the mag. I just noticed the difference between the two. If the tips are irregular you get different coal. accubond tips are difficult to keep all the same. Just trying to make that perfect bullet to get tighter groups. If you measure to the tips then some will have to jump more than others.

I have found my most accurate groups about .050 to .055 off the lands. For years I did the standard .020.  Load up 4 rounds each at .020, .030, .040, and .050 and see which set holds a tighter group. You might be surprised. Just focus on your groups and when you find which depth holds the tightest group then you can zero the rifle perfectly with that depth. I shot Nosler for 20 years and think they make a fantastic quality bullet. I find Barnes group much better in both my 22-250 and 7MM.

[high country]

I have seen barnes xbt bullets shoot their best at .120" off......you read that right, near 1/8" inch......then the next gun is .020"....its the fun. Run a ladder for powder and then go back an play the seat game.

[jamesjett]

 

I have seen barnes xbt bullets shoot their best at .120" off......you read that right, near 1/8" inch......then the next gun is .020"....its the fun. Run a ladder for powder and then go back an play the seat game.