Hey I was just seating some bullet and the lyman book gave me 2 different direction, first they say the bullets should generally be seated to the max overall lenght, and then for the caliber I am reloading the 7 mm rm they list some oal from 3170 to the max 3290. How should it be for Hornady 139 SST and how far appart would be acceptable?

I don't have current Lyman or Hornady books but in my opinion they are only a guide, and a statement on what THEY did.

As we all have said before, if it's not jamming into the lands, fits in the magazine and feeds,
is'nt unnecessarly too far into the case,(say preferrably not much below the bottom of the neck), your set to go. And if it's within their measurements well and good.

Your long term ideal is to be as above, and have good accuracy with the distance from the lands that suits YOUR rifle. You may not be able to find much difference though.

quote:

As we all have said before, if it's not jamming into the lands, fits in the magazine and feeds,
is'nt unnecessarly too far into the case,(say preferrably not much below the bottom of the neck), your set to go. And if it's within their measurements well and good.

I like to also load to the cannelure if one is provided or load a minimum of one caliber deep.....but the above information is very good.

I like to do my load development in two separate stages. Firstly, I load up several batches of 3 cartridges, starting at a safe minimum and increasing powder charges in 1/2gr increments. For this stage, I seat the bullets for maximum overall length, but within the following parameters:

The bullet must be seated at least 1 calibre into the case neck;

The loaded cartridge must fit into the magazine without binding.

Once I have settled on a load (a combination of lowest extreme spread, smallest group and proximity to the point of diminishing returns), I load up several batches of 3 cartridges IN THAT LOAD, shortening overall length by 0.5mm on each batch. These I shoot for groups. The smallest group is the load / configuration my rifle likes best. When adjusting seating depth, I typically see groups shrinking to a point, then opening up again. I have noticed that once the groups open up again, I am in 'diminishing returns' territory. I can't claim a definite correlation - just that I've noticed this often enough to make the comment.

In a nutshell - see what seating depth your rifle likes.

quote:

The bullet must be seated at least 1 calibre into the case neck;

The loaded cartridge must fit into the magazine without binding.

I concur with Rikkie here, and add one additional caveat: The bullet must not be seated so far out as to stick in the origin of the rifling - it must be at least 1mm shorter than that. (Except for cast-bullet target loads made up for use in a single shot rifle.)

I generally seat the bullet as far out as possible.


The limitation are:
It should be seated deep enough so the bullet doesn't fall out.

It should be seated so as not to touch the lands.

And usuall the biggest limiting factor, it must fit the magazine.

If it has a crimping groove, I usually try for it.

I've noted that SST's need to be seated MUCH further out than other bullets in order to get close to the lands due to the shallow ogive - way out past the cannelure with 130gr in the .270

I always use the Hornady L-N-L (formerly Stoney Point) OAL gauge & bullet comparator to set OAL, rather than measuring to the bullet tip because of the variance introduced by differences in bullet geometry.