seating depth with ling throat

[JMA]

When reloading for a rifle where you can not come close to reaching the lands because of mag length
restrictions and long throats ie. 5.56/.223 Wilde, Weatherby is it worth playing with seating depths or just load to Magazine length ?

 

[Ol’ Ed]

IMO, if it’s for hunting, load to the mag length with the bullet you want to use and try working up a load that will shoot. If you can’t get it to shoot, and the barrel doesn’t have too many rounds on it, take it to your gunsmith and have him do a setback. If the barrel has had a lot of rounds down it, rebarrel. If it’s not for hunting (or where you don’t need a hurried follow-up shot), make it a single shot and work up a load that shoots closer to the lands (longer than mag length) to find the accuracy you’re looking for. That’s usually the criteria I follow when faced with long throated rifle barrels.

 

[gman47564]

in my opinion a rifle has a lot of different seating depths that will work.. and work well... don't be afraid to jump them... seat the bullet to what you need to fit your mag and do a good powder work up.. pretty good chance you will find a good load

 

[Ned Ludd]

With a specific throat length, reloaders often work to find a seating depth optimum within a relatively narrow window off the lands. On occasion, you will hear about people jumping bullets .050", .100", or even more, if that's what it takes to tighten up the groups. The reason most don't start that far off the lands is because seating the bullet that much deeper in the neck (as opposed to .010" or .020" off, for example) reduces effective case volume and can raise pressure considerably. So it's not uncommon for those having to jump a bullet a relatively long distance to also reduce the charge weight to accommodate the potential increase in pressure. In other words, it can be a little more work.

Nonetheless, it is certainly possible to carry out a fully functional seating depth test within a window much farther off the lands in a rifle with extremely long freebore, or having to load to mag length. Berger has a seating depth approach originally designed for VLD bullets, which can sometimes be finicky, that covers a very wide seating depth range initially to find an optimal seating depth region, after which you would again test seating depth just within that region in finer increments to find the optimal seating depth:

https://bergerbullets.com/getting-the-best-precision-and-accuracy-from-vld-bullets-in-your-rifle/

Your situation is not all that different. I would suggest finding the longest acceptable seating depth that you believe will still leave plenty of bullet bearing surface in the neck, as well as the shortest acceptable seating depth that will leave the boattail/bearing surface junction above the case neck/shoulder junction. The difference between those two would be your initial overall seating depth test range. You could then test seating depth across that range in coarse increments initially, to find an optimal seating depth region, using group spread as your readout. You can then test in finer increments to either side of anything that looks like an optimal window within the larger region. In other words, carry out a typical seating depth test that is simply offset relative to the lands by some distance due to the long throat or loading to mag length. I think you may find it is possible to identify an optimal seating depth window even at a distance fairly far from the lands.