Powder Charge Advice

[mdslammer]

Hello,

I'm loading some Sierra .338 250gr. MK HPBT with H-1000, Lapua Brass and 215M Primers. The max charge for this is 100.0 gr.

I would like to load some Lapua Scenar 250gr. bullets with the same powder/brass/primer config. But the only reference from the V.V. manual uses N-560. I've tried this last week and it
was very disappointing at 2000yds.

The difference I can see is the length of the projectiles. The Sierra being slightly longer.

The question is, can I load the same amount of powder for the
Scenars 250gr. bullets as I'm doing for the SMK 250gr.

Thanks.

Mark

 

[ksthomas]

Re: Powder Charge Advice

Standard reloading cautions apply (start low, and work up as pressure signs allow), but yes, you can use the data for the Scenar that you're now using for the SMK. The H1000, incidentally, is an excellent powder for the 338 LM.

 

[Deadshot2]

Re: Powder Charge Advice

When using different bullets I don't worry as much as total length as the bearing surface. To do a quick and dirty measurement I'll roll the bullet on a stamp pad then roll it on a piece of paper, then measure the width of the band the bullet rolls. Repeat for my new bullet. If the band is really close that indicates that I'll have pretty much the same amount of bullet in contact with the bore. Also mic bullet to see if they're exactly the same diameter.

If these measurements are close I start fairly close to the same charge weight. If widely different, with the new bullet being longer in the bearing surface or larger in diameter (by .0005"-.001") I start much lower for my initial workup.

To get an accurate measurement of the bearing surface just use two caliper mounted bullet comparators, inserting the boat tail in one and the tip in the other. Great for comparing bearing surfaces quickly.

 

[mdslammer]

Re: Powder Charge Advice

Thanks guys for helping me out. Good info.

Mark