Comparator question

[bob_dobalina]

Finally playing around with measuring with the Hornady comparators. I was surprised that my bullets that were all seated, I believe, on the same depth setting, with RCBS dies, had different lengths with the comparator. Doesn't it seat by the ogive, or is it setting the depth by the tip, which doesn't seem very accurate? These loads were from last year, so perhaps I did fiddle with the depth screw, but it seems unlikely. Thanks

 

[OU812]

They seat off of the ogive but in some cases the tip can contact the bottom of the seating stem, depending on the bullet.

 

[waveslayer]

What bullets are you Shooting. If they are VLD shape you will want a VLD seating stem in your dies

My wife thinks I only have 3 guns

 

[joelkdouglas]

And even when the bullet tip isn't making contact with the die, I've noticed some bullets (Accubonds notably) aren't the most standardized bullets out there...

But I don't think I can notice the variance on paper.

 

[Darkhorse]

If your not prepping your cases with a Primer Pocket Uniformer, then the varying measurements could be caused by the primer and not the bullet. This tool cuts out the radius in the bottom of the primer pocket and allows your primer to fully seat.

 

[bob_dobalina]

Thanks for the responses. Good info on the Primer pocket uniformer. I'm shooting a 180 grain 30 cal. Barnes TTSX. So, besides being able to accurately measure distance to the lands (in combination with an OAL Gauge), and being able to seat the bullet's ogive an accurate distance off of the lands, what can I do with the comparators? For instance, reloading manuals will give a "tested" COAL which is to the tip of the bullet, but if the ogive to the tip of the bullet is variable, the COAL is kind of a ballpark number. It would be great if manuals listed the ogive measurement.

 

[Rol_P]

A slight variation between manufactures could yield different COAL so published data may be of limited use except to get you in the ball park. NYDan and I saw this when he used his comparator to check some of my loads and came up with a variance from my number. Good luck, Rol

 

[truck driver]

And even when the bullet tip isn't making contact with the die, I've noticed some bullets (Accubonds notably) aren't the most standardized bullets out there...

But I don't think I can notice the variance on paper.

Yep the Accubonds are all over the place in .358 caliber at least the 200gr ones are. I had to back my Redding Micrometer seater off .005"-.010" and adjust to get the same depth with each bullet. The o-give is all over the place and no 2 bullets the same. The .358gr 225gr PT is .001"+or- and most are spot on.

 

[ElmerThud]

Seating my AB's carefully, while dimentionaly I have to make changes with the micrometer on the die, it's rarely more than .002"
When I OAL check the loaded rounds, they will measure from 3.396" to 3.400" so 3.998 +/_.002"

That's with the .257 110gn AB ..... But then, the pointy bit doesn't matter, the ogive does.

 

[Whitesheep]

As others have said it is lack of consistency in the bullet's form. Berger's seem to have the largest spread, but on contacting them they indicted the data from my measurements was well within their specs. Nosler BT's are really consistent for me as are all the Sierra game king bullets I have used. I used to sort bullets by length, but with on about +-0.003" I figured I was wasting my time for hunting/silhouette loads. At that level of variance all bullets are well within the 0.040" that Berger suggests are the steps jump that impact accuracy.