COAL Varies When Seating Bullets. Problem???

[RaptorAddict]

I just recently picked up the RCBS Matchmaster micrometer die for my 6.5CM. the COAL I need is 2.810. I'll have it set right at this measurement, but I'll have some measured at 2.810 and some will be at 2.811 and 2.812. Does anyone have this issue? If so, what causes it to be off and will that small of amount of measurement have a drastic effect on accuracy out to 1400 yards? I noticed I'll hit a 12"x24" plate 4 times in a row out at 1100 yards and then miss a couple here and there. Me? Wind? Or the COAL? Trying to see if I can leave the COAL out of the miss equation. LOL! Rifle is Sako TRG 22.

 

[37L1]

I just recently picked up the RCBS Matchmaster micrometer die for my 6.5CM. the COAL I need is 2.810. I'll have it set right at this measurement, but I'll have some measured at 2.810 and some will be at 2.811 and 2.812. Does anyone have this issue? If so, what causes it to be off and will that small of amount of measurement have a drastic effect on accuracy out to 1400 yards? I noticed I'll hit a 12"x24" plate 4 times in a row out at 1100 yards and then miss a couple here and there. Me? Wind? Or the COAL? Trying to see if I can leave the COAL out of the miss equation. LOL! Rifle is Sako TRG 22.

1 or 2 thousandths probably not going to make a difference. Changing conditions and shooter's input will.

 

[Tokay444]

Measure to the ogive and see if they’re any more consistent in length. The tip of the bullet is the least accurate part.

 

[RaptorAddict]

Measure to the ogive and see if they’re any more consistent in length. The tip of the bullet is the least accurate part.

Never thought about the tip. Hmmm. Using Lapua 139gr Scenars. Tips could be slightly uneven I assume.

 

[BuildingConceptsllc]

Never thought about the tip. Hmmm. Using Lapua 139gr Scenars. Tips could be slightly uneven I assume.

This is why we all use BTO measurements, it's more accurate. Even with bto, 1 or 2 thou difference isn't uncommon nor is it a big deal unless you are into the lands, then I suppose it could potentially be something. If you are jumping then 1 or 2 thou won't matter enough to worry about it.

 

[RaptorAddict]

This is why we all use BTO measurements, it's more accurate. Even with bto, 1 or 2 thou difference isn't uncommon nor is it a big deal unless you are into the lands, then I suppose it could potentially be something. If you are jumping then 1 or 2 thou won't matter enough to worry about it.

This is good to hear! So I can throw the slightly off COAL measurements out of the miss equation. The BTO measurements are fine.

 

[ShtrRdy]

If you measure just the bullet length I would suspect you'll see that much variation, or more.

 

[Baron23]

Measure to the ogive and see if they’re any more consistent in length. The tip of the bullet is the least accurate part.

This and I sort of said the same in your post about your process steps.

Dunno about tipped bullets, but open tip can vary a good bit in overall length

 

[Marine52]

This and I sort of said the same in your post about your process steps.

Dunno about tipped bullets, but open tip can vary a good bit in overall length

Spot on. Also, when sizing your brass, if there is a variation in base-to-datum line, this will show up as variance in bullet jump since the shoulder of the case (datum line) is what stops the forward movement of the case in the chamber. So BTO measurements are what you should use as long as your brass sizing procedure produces consistent results. And as others have said, 1-2 thousands off is no big deal.