I have been loading Hornady .308" 168 grain BTHP 'National Match' bullets to shoot with Benchmark and Varget powders. When preparing to set the seating die to seat the bullets at their proper depth, I noticed a variation in the COLs. I know that bullets may or may not be perfect, so for the hell of it, I took a group of bullets, measured their length with a dial caliper and separated them by length in groups. It seemed like most of the bullets were .218" in length, and .220" was the second largest group. Then there were a handful at .214" and even one that miked at .211" (saved that one for a fouling shot).

Now I do understand that the seating plug grips the bullet around the sides of the bullet, not the tip, but the tip is where you measure it at. My solution was to set the COL at 2.800" using the bullets that were .218" in length, and not worry about it after that.

Is this on the right track? Since I was shooting half of the rounds at a bench for accuracy, I further separated the rounds with .218" length projos for my accuracy testing, and used the rest for field fire off of a bipod. Or is this splitting nonexistent hairs?

Variations in the bullet length may or may not have an impact on the actual distance the bullet moves before it engages the lands. That will bepend on the consistancy of the ogive of the bullet.

Not an effort I would do.

Actual bullet length is unimportant and does vary. Length from base to ogive is more important (Ogive in this context being the point on the 'taper' of the bullet which will engage the rifling.) This can be measured with a comparator, as supplied by Sinclair, attached to a vernier.

quote:

Originally posted by sputster:
Now I do understand that the seating plug grips the bullet around the sides of the bullet, not the tip, but the tip is where you measure it at. My solution was to set the COL at 2.800" using the bullets that were .218" in length, and not worry about it after that.

Is this on the right track?

Absolutely, this is how it should be done.

+4

The guys above are right on.

Don

Hey Sputster, Also agree with all the posts above.

As long as the Bullet "Tip" does not touch the inside of the Seating Stem, you might want to try converting OCL to ODL and forget about sorting Bullets by length.

The key to consistency is having the Datum Point on the Ogive the same distance from the Lands, as the other folks said.

Best of luck to you.

Is the PTG comparator same as the Sinclair?

How do they comapre to Hornady's comparator?

Thank you all. In the past I had merely been loading hunting loads and was happy with hunting accuracy, but have decided to take the 308 Win varmint type to a higher standard.

The one coment I would make would be to weigh the bullets and be sure short and longs all weighed the same + or -.
Judge Sharpe