Am I Doing Something Wrong?

[jay666d]

Recently I have used a Hornady OAL Guage, a modified case and an 80Gr A-Max bullet along with the Hornady comparator to determine how long I should be loading my rounds.

 

I now know that to touch the lands, base to ogive needs to be 1.935" (Turns out, on previous loads, I've been jamming it quite far into the lands... Could be why I've always seen pressure signs on the primers!)

 

I'm using a Redding Competition Bullet Seater and new PPU brass to seat the 80Gr bullets... Out of the 20 rounds I've just loaded, 16 of them were within -/+ .002" but the other 4 all seated at about 1.955"...I had to adjust the bullet seater to bring them in line with the others!

 

Does anybody have any idea why this might be?

[The Gun Pimp]

Mass-produced bullets will vary - the 100 A max bullets in your box could be an assortment from half a dozen different swaging machines.

 

Might also be useful to make sure the bullet-seating stem in your die is pushing on the ogive and not the tip.

[Laurie]

Check that the seater stem cavity is long enough to allow the bullet to enter it fully without bottoming. It's common for VLDs and long nose + tip types like the A-Max to suffer this problem. Redding does list VLD seater stems.

 

The Berger Bulletin touched on this a while back with relation to its VLDs and quotes inexplicable COAL variations of up to 0.025" when this problem arises matching your findings.

 

http://www.bergerbullets.com/reddings-new-bullet-seating-micrometer-plugs-for-berger-vld-bullets/

 

If this is happening, concentricity will be poor too.

 

An alternative to an expensive seater stem replacement is to get somebody to machine it a bit for you. There are several people on the forum who can do this.

 

Another cause of comparator COAL reading variations is the bullets themselves as seen in CBTO readings (Comparator base to ogive) and measuring / batching bullets will reduce this to near nil. However, unless your bullets are absolutely dire, and I wouldn't expect to see more than a few thou' range in the modern A-Max, it won't induce a 20 thou' change into the overall COAL.

[jay666d]

Thanks for the input guys... Looking at the bullet tips, (or just below) there does seem to be a faint ring.

 

It would appear the way to go is to get an A-Max or VLD spesific stem!

[1967spud]

got them here

[jay666d]

I will no doubt be in touch soon Mark... Cheers. :-)

[onehole]

Hornady can make life interesting at times ,,,,,doh!!!,,,,,,,,,,All good advice above ,,,the one other thing that can happen is that you have a micro crack in your seating stem,,,,I,ve broken one in the past which gave similar variations in measurements.You could check this by careful examination with a ten x lens or similar. Worth checking,,,,,cheers ,,,,O