I was reading my #49 Lymans book today and I noticed that it said for 130 grain SPBT in 270 Win that the OAL is 3.250. Now it says for 270 in general that the OAL is 3.340. On Noslers sight it also says 3.340. Now I was seating mine at 3.320, should I re-seat them to 3.250 or leave them?

Anyone know why they would list different OAL for different weight bullets? Lymans has a different OAL for every weight.

The Hodgdon site lists 120 grain @ 3.270 OAL, 130 grain barnsx at 3.23 OAL, 130 hornady at 3.180 oal, 135 grain sierra's at 3.34 OAL, 140 grain hornady's at 3.28 OAL......?????????

Grant, 3.340 is the maximum length set by SAAMI ( Sporting Arms and Ammunition Manufacturers' Institute)...... this is to ensure that all manufactured ammo will work in all guns !!!

When you see an overall length listed for a particular bullet that is the length at which the load data was derived from.
Nosler manuals #6 and prior do not list the individual bullet OAL, only the max.

The reason they do this is to have an optimal amount of bullet in the case. With the heavier bullets sometimes more bullet is in the case than what would be optimal but it needs to stay under the max. length.
Keep in mind different bullet weights and styles are different lengths.
A Sierra 110 gr. bullet is 0.800 in oal. compared to a 130gr. Nosler Ballistic Tip at 1.220

So in other words, I should seat them to 3.250?

I'm using 130 grain Nosler Accubonds and didn't seem to have any chambering issues at 3.320

I thought the different COAL was to accommodate the different ogive shapes and the needed distance to the lands, average or typical. It's a starting point that you adjust to tune to your individual firearm within maximum COAL.

So the 3.250 that they list is a minimum COAL that you can start from. I was always under the impression that you seated your bullet at about a thou and a half off the rifling.

I always measure my distance to the lands regardless. I doubt they recommend loading that close to the rifling. Loading VLDs within 0.005 or 5 thousands is considered very close. Too close a it spikes pressure. Barnes bullets are recommended to seat 0.050 off the lands.

The overall cartridge length "as tested" is where the recorded pressures are recorded. The maximum O/all length is what will fit in the magazine and chamber of EVERY gun. If you seat the bullet deeper than the "tested O/all length" then your pressures will be higher but velocity will not increase much. If you seat them lower the pressures will drop - but the velocity won't changes much.
If you seat your bullets to the longest length that you can you have room for a bit more powder that will increase velocity.
This is a balancing act for the reloader because once you step away from the "as tested" data you are on your own. Once you work up a load you should not change the O/all length as tested (your testing) because it is likely (doesn't always) to change the accuracy of your load. If you seat longer the pressure goes down and the peak pressure happens later so the hamonics of the barrel with that load change. Once I get a load that shoots I don't change anything until I buy a new lot of powder.

After reading more earlier in the Lyman book it does state that a reloader should seat his or her reloads at the OAL listed for each bullet weight they show. Hunting season is over so I might as well test some at the recommended length and see what happens. If it groups better I can always push my older reloads in a bit farther. Thanks for the info guys!

Im too lazy to do the "off the lands thingy" my reloads fit in the magazine and chamber when I need them to. my 170 yes thats not a typo .270 loads get loaded to just fit in the magazine and they sure take some adjusting to load.

Grant, To a handloader the OAL is somewhat meaningless !!!

You can load to whatever length you desire as long as you develop the load in a proper manner.

Elvis wrote:

Im too lazy to do the "off the lands thingy" my reloads fit in the magazine and chamber when I need them to. my 170 yes thats not a typo .270 loads get loaded to just fit in the magazine and they sure take some adjusting to load.

ChamberPot wrote:

Grant, To a handloader the OAL is somewhat meaningless !!! You can load to whatever length you desire as long as you develop the load in a proper manner.

+1000 to both

Keep safety as the highest priority, you can basically do whatever.
Thats how the wildcatter start their never ending search of the perfect combo.