Much Ado About Nothing

[Rory McCanuck]

As I am still relatively new to reloading, I am doing my best to
be as consistent as I can, changing only one variable at a time.

Everything has been going well, but overall length has been
jumping around, but only with these Hornady 150gr .312"
They are shooting into tiny groups, so I know they are a good
bullet, but the inconsistent lengths have been bothering me.

As an experiment, I measured 106 of the bullets today, and
they ranged from 1.053" to 1.074". Well, that explains it, and
gets me wondering how important it really is.

I figured it must be the exposed lead tip deforming
that causes the difference, so I took the seating punch out of
the die, and measured from the bullet base to the end of the
punch. Instead of a .021" difference, the biggest variation I found
was .002" That really eased my mind, and taught me a couple
of things.
1. That bullet comparator that Hornady sells might be more
useful than I once thought, and
2. Don't sweat the small stuff.

 

[CyaN1de]

Just guessing here that you are measuring to the tip of the bullet?

Either get (or make up) a comparator that will allow you to measure to the ogive of the bullet.

Measuring to the tip of any bullet is a waste of time and energy.

I have used a piece of cutoff case that would fit the bullet at least somewhere between the tip and the portion of the bullet that will contact the lands. At least you can get a consistent OAL this way.

I used this method until I purchased my comparator set.

 

[Suputin]

Measuring to the tip of the bullet is a total waste of time. The OAL values are useful only to get the round in a magazine. You worked out a solution to the problem all on your own. We don't see that much around here.

 

[Rory McCanuck]

You worked out a solution to the problem all on your own. We don't see that much around here.

Lol, good point. I was sadly proud of figuring it out myself

 

[cosmic]

Well - My method is to measure several bullets to the tip, and take a representative bullet as a "reference" bullet. Record the length as measured to the tip. Establish cartridge OAL in the usual manner. When making a new batch, select a bullet with a similar length as the reference bullet and set up the sizing die accordingly. Of course, if you change lots (or even boxes if its Hornady!) you have to start all over again.

 

[Eagleye]

Only a few types of bullet actually will be even remotely similar in length to the tip.
Measuring with a comparator or to the ogive at a specific point is far more accurate.
As one poster mentioned, OAL is only useful to be sure that the loaded round is not too long for your magazine.
Regards, Eagleye.

 

[cosmic]

Eagleye - perhaps you mis-understood my methodology. I establish a reference length from a given box of bullets. Its not hard to find one that's about average. Its not hard to repeat the effort with another bullet from the same box - I lock my verniers and check a few. Years ago, I did it another way by seating the original reference bullet in a dummy case, and would use it from batch to batch (same box of bullets)
To verify my approach, I borrowed a buddies comparator and got about 1 to 2 thou repeatability - cant remember the value exactly.