How consistent is your OAL/COL?

longwinters · Dec 26, 2004

When you are seating your bullets how consistent is your OAL measurement? For example . . . If you set up your die/press to measure 3.330 on the 1st cartridge will every one after that be exactly that measurement. Does this follow with any bullet/manufacturer that you use? I understand that you would have to re-set the die when changing bullets, but are your results always exact with new bullets? I find differences in spitzer types especially, but sometimes even the polymer tip ones.

Long

DLJ · Dec 26, 2004

longw,
I dont use any of the high end seating dies and my cols vary by a couple few thousandths either way. As you say there is some variances in the tips of some bullets...both tipped and hollow. If I'm working with a barrel that I seat into the lands, I will use a comparator like the one Sinclair sells that measures off of the base of the ogive.

Ol` Joe · Dec 26, 2004

Longwinters,
The OAL of my rounds is set and measured with a Stoney Point comparator. The tip to case base lenght will vary no matter whos` bullet you use. The tips of the bullets get banged up or deformed giveing a bullet OAL variation no matter what shape, The plastic tips seem, in my experiance, to vary in lenght even more. The comparator tool measures off the ogive and I find very consistant OALs when measuring this way with "most" manufactures bullets. The basic shape of a bullet is very uniform in the body within like brand, wgt, and style. The ogive should, and in most cases will, measure the same even when changing the lot used from bullet to bullet.

The OAL of my ammo measured without the Stoney Point will likely run +/- ~.003 depending on the bullet used, When measured with it (the Stoney Point) I get almost all my ammo to run the same OAL, or +/- .001 variation max.

Hope this isn`t too ramblin`.....................

Check out the tool here..http://precisionreloading.com/stoneypoint.htm

FOTIS · Dec 27, 2004

Very consistant. I use the Hornady micro adj. seating system.

longwinters · Dec 27, 2004

I use the Stoney Point Comparitor, especially when going from one type bullet to another. Just curious what would be considered "the norm" for OAL measurements.

Long

Ol` Joe · Dec 27, 2004

longwinters":3cg3adn1 said:
I use the Stoney Point Comparitor, especially when going from one type bullet to another. Just curious what would be considered "the norm" for OAL measurements.

Long

If you are measuring the OAL of a round with the same bullet I`d expect the variance to be zero or very close to it with a comparitor. No more then a thousanth or so. The differance when jumping from style to style or brand to brand even with-in the same wgt would be impossible to guess at. I`ve seen .1+" variance with a swap from the Hornady 139 gr 7mm SP to a Sierra 140 gr SP in base to tip OAL in my 708 with the same comparator oal. Noslet BTs will run somewhere in the middle of this range. Throw in a round nose bullet and I haven`t a clue what the differance will be.
If you measure with a comparator useing the same bullet with the same seater set up there shouldn`t be any variation or =/>.001". If you get more IMO you have a tooling problem, started a new lot of bullets and the maker changed something in the manufacture or you can`t work / read a caliper

Then too, I once bought a box of 150 gr .308 from a well known maker that was pure ...................let`s say they were no good.