I just loaded my first 40 rounds of reloads ever for my .300 Win Mag. I knew the overall length was ok up to 3.340 but I checked a box of factory Federal 180 Nosler Partitions and found that the OAL on them was between 3.297 to 3.305 so I set my die to try for 3.305. I ended up getting them all between 3.301 to 3.309. The bullets I loaded were 125 gr Nosler Ballistic Tips over 10 rounds each of 77.0 gr, 78.0 gr, 79.0 gr, 80.0 gr, of RL19. I of course was going to start with the lighter load and work up during my shooting watching for pressure. My question is, does my OAL for my reloads seem ok? Do I need to reset them to be longer so as to avoid high pressure? And is it normal to have the spread I did for my OAL length when I was seating the bullets? I figured the die didnt move so I was curious as to why the spread, although it wasn't much. I am using Winchester once fired brass and WLRM primers also. Thanks!

Hi, in many handloading books you can find your answer.
Overthere, every gun-bullet-load have the perfect combination. If you are looking for the best load for your gun, you must also find the better OAL for your cartridge.
Start with one misure and than work up, sitting the bullet near the groowe. Be careful, work in little steps. Probably the best OAL will be longer than 3.340.
Faina

Thanks, I looked in my Nosler book and was unable to find info. I probably need to look again. I was more worried about pressure than anything. It did not seem like there was much room for the bullet after I put the powder in. They were not compressed loads though.

Once you get into reloading a bit further, you'll learn that all chambers are cut differently, including the amount of freebore. Whatever the specs state for your cartridge are minimum specs - e.g. a .300 Win Mag chamber must be able to take a loaded round of such and such length. Factory rounds are loaded pretty much to (or even below) specs to provide an extra margin of safety. After all, the ammo manufacturers have no control over the chambers in which their ammo will be fired, so they err on the side of caution. Your chamber, however is likely capable of accepting longer rounds. One way to find out about your particular chamber and what seating depth will keep your bullets off the lands is to use a gizmo like this:

Hornady Seating Depth Tool

The issue regarding seating depth vs pressure is primarily about making sure your bullets stay OFF the lands. Seating a bullet deeper may have an effect on pressure, but it is negligable compared to being off the lands. So don't worry about the variation in over-all-cartridge-length (OACL) as long as you are sure the longest round is off the lands.

The reason you see the variation in OACL is primarily because you likely measure OACL over the tip of the bullet. That is not a very precise way of measuring - as bullet tips vary quite a bit. The better way would be to measure OACL using a "Bullet Comparator", which allows you to measure over the bullet ogive. Had you done that, you would still have come up with some variation in OACL, but likely not as much as you are currently seeing. Bullets vary (even over the ogive), that is why it is important to stay off the lands a certain amount (.005 or .010", say), to ensure that all bullets are off the lands.

When you get more experience, you'll find out it is also possible to load into the lands, but for various reasons this is not a good practice for general rifle use and tricky for inexperienced reloaders.

- mike