Coal inconsistent with hornady dies

[sundance1972]

Recently bought a set of hornady new dimension dies(used) for a 7mm rem mag and am having very incosistent results with the seating die. COAL seems to vary +- around 6 thou no matter what style of bullet used. I have measured the cases before and after priming, all are within 2 thou of each other, so no problem there. I set the die to touch the top of the case mouth and backed it off 1/8 turn as recommended by a gunsmith i know, because he says there is no need to use the built in crimp feature in a bolt action rifle. Never had this problem with rcbs dies, COAL is always very consistent. Maybe i need to set them up differently??
Any help would be appreciated, thanks!!

 

[Whelen B]

possibly (???)
- the seater shape doesn't match bullet well and is actualy grabbing the bullet ogive sometimes and pulling bullet back out a few thou before it releases. You can feel that usually. Lightly debur lead edge of seater and/or rub a touch of parafin wax on the edge.
- bullets themselves made with slightly different nose ogive tolerances which affects COAL
- bullet tip formation or deformation affects COAL

 

[NormB]

Recently bought a set of hornady new dimension dies(used) for a 7mm rem mag and am having very incosistent results with the seating die. COAL seems to vary +- around 6 thou no matter what style of bullet used. I have measured the cases before and after priming, all are within 2 thou of each other, so no problem there. I set the die to touch the top of the case mouth and backed it off 1/8 turn as recommended by a gunsmith i know, because he says there is no need to use the built in crimp feature in a bolt action rifle. Never had this problem with rcbs dies, COAL is always very consistent. Maybe i need to set them up differently??
Any help would be appreciated, thanks!!

You haven't changed loads and are seating on a compressed powder charge??? If neck tension isn't enough the powder may push the bullets back out differently.

As said before, check the seating stem. The dies were used and the stem could be damaged, burred. Hornady now offers an Amax seating stem. it contacts further down the ogive and should therefore result in straighter seated bullets. The hole is deeper and shouldn't mess with the tip. You can order direct from Hornady in your calibre.

Also the old type seating stems were stamped on the top. The resulting small raised burrs can be sanded off with fine paper on a flat surface. This could have a minor effect on seating. Hornady doesn't stamp them now.

NormB

 

[Janeau]

If you mesure COAL at the bullet tip you will get variation. You MUST use a bullet comparator on the ogive to get consistent COAL.

Here is one model : http://www.sinclairintl.com/cgi-bin/category.cgi

Using a comparator is also the only exact way to seat your bullet at a know dimension from the chamber throat.

 

[mike shickele]

If you mesure COAL at the bullet tip you will get variation. You MUST use a bullet comparator on the ogive to get consistent COAL.

Here is one model : http://www.sinclairintl.com/cgi-bin/category.cgi

Using a comparator is also the only exact way to seat your bullet at a know dimension from the chamber throat.

I double that.
Mike

 

[Finger Toes]

If you mesure COAL at the bullet tip you will get variation. You MUST use a bullet comparator on the ogive to get consistent COAL.

Here is one model : http://www.sinclairintl.com/cgi-bin/category.cgi

Using a comparator is also the only exact way to seat your bullet at a know dimension from the chamber throat.

Exactly, try measuring the bullet OAL they aren't all the same. A comparator will show how uniform you seating depth is. That's more important for accuracy although it would be nice if all bullets were exactly the same.