seating depth

[corbin9191]

I am just wondering, how long do you usually seat a bullet from the lands for the best accuracy? I know that I will have to play with the seating depths but I always get a flyer when shooting groups and I think the seating depth is the problem. The rifles will be 7mm wsm, 7mm rem mag, 270 win, 243 win. Thanks

 

[Ol` Joe]

I start at the lands and work my load up to max then reduce seating 0.005" until the sweet spot seems to be reached.
You can`t just pick a lgt IMO and have it magically work in every rifle. Mine all seem to want something within 0.050" of touching though, with the exception of a old Swede I had that liked them 0.1+" off.

 

[remingtonman_25_06]

Yep, I just start at the lands with that particluar bullet for initial testing. Once I've found my load, I will start to seat .005" deeper. Most the time, my best accuracy is at the lands or within .015"

 

[Big Squeeze]

I am just wondering, how long do you usually seat a bullet from the lands for the best accuracy? I know that I will have to play with the seating depths but I always get a flyer when shooting groups and I think the seating depth is the problem. The rifles will be 7mm wsm, 7mm rem mag, 270 win, 243 win. Thanks

.............That will strictly depend on each individual rifle.

Here is a good formula to use.

For HUNTING loads (magazine loadings).......Start out with the maximum COAL that your magazine`s length will allow where the bolt can still be cycled effectively and load 3 to 5 rounds using the powder, appropriate charge and bullet of your choice. More than likely, the bullet will not be touching the lands..........Next, load 3 to 5 more rounds using the same identical bullet, powder and charge with a COAL of 10/1000ths less......Repeat again and reduce the COAL by another 10/1000ths.........Repeat again and then one more time..... Put each cartridge group into a small zip lock baggy and label all info accordingly on each baggy. Then test fire for accuracy recording the group sizes for each group. Then determine which COAL gave you the best accuracy and record those results.

The goal is to determine, at what COAL does your rifle give the best accuracy using a specific powder, charge and bullet. The sweet spot variance for any given rifle, can vary in distance from jamming the bullet into the rifling out to maybe 80/1000ths of an inch away from the lands.

For RANGE loads (one by one loading; no magazine loadings)......Start out with the bullet jammed 5/1000ths into the lands and load 3 to 5 rounds......Then load 3 to 5 more backing down 10/1000ths....3 to 5 more backing down another 10/1000ths and so on. Label each group as above and test fire for accuracy.

When you change your bullet, powder and charge,,,start over and begin the same above process.

 

[super-7]

I would suggest that for a practical every day hunting load for any of the above rifles listed that you start off seating bullets .010 to .020" off the lands. Remember that if you start off with bullets seated in conact with the lands that pressures may increase above safe levels, if you want to start out with bullets touching the lands use reduced loads. There is a good article in april's shooting times, by Lane Pearce, on bullet seating and it's affect on accuracy. Also take into consideration that there is some very accurate factory ammo, sub minute loads, where bullets are seated to fit in every make and model of rifle. If it is competition shooting depth will be critical, hunting situations seating depth will be more forgiving and still provide sub-minute groups.