Question about seating bullets near or touching lands

[MadDog]

I am going to try a few more things to try to get acceptable accuracy out of my upper. One thing I want to try is to seat some 240gr SMKs near or touching the lands. My barrel has a very long throat and I will not be able to use mags for this experiment. I really just want to see if it makes any difference.

My question is how will this change pressures and velocities from my previous loads? Should I start with a lower load even if I am only loading subsonics? Where would you start relitive to loads that were running around 1000fps?

Also, what have you found to be an optimal distance from lands for accuracy with subsonic loads?

Thanks,

Joe

[Garrett]

One thing I want to try is to seat some 240gr SMKs near or touching the lands. My barrel has a very long throat and I will not be able to use mags for this experiment.... My question is how will this change pressures and velocities from my previous loads? Should I start with a lower load even if I am only loading subsonics?

In other words, you are going to seat the bullet out farther for a longer OAL. This increases your internal case capacity, which will decrease the internal pressure. The result will likely be a decrease in muzzle velocity. (unless you actually jam the bullet into the rifling. This would increase the initial resistance, which will cause pressure and MV to increase).

I would leave your powder charge alone initially. Seat longer and test for velocity and accuracy. Adjust from there.

[MadDog]

Thanks for the reply. Going with the same loads was my plan but wanted another opinion. I have not ventured far off the beaten path in terms of loading subsonic ammo.

Thanks,

Joe