Reloading 100 grain 300 blackout

[Matt300BO]

Hello All! My first post and I am wondering if anyone has any information or starting points for a round I am trying to reload.

I'm using the following:

Lapua 100 grain 30 caliber bullet
300 blackout brass
Winchester or CCI small rifle primers
Either Alliant 300 MP (which I'm told is similar to H110)
Or... H335
Or... RX15 (Alliant Reloder 15)
OPEN TO IDEAS ON WHICH OF THESE THREE IS BEST...

Lastly and most importantly I'm at a loss for a starting point on this load... closest I can find is a Hornady V-Max 110 grain bullet which calls for H110 starting with 19.0 grains of powder...

So I'm wondering with a slightly lighter bullet being 100 grains should I stick with 19.0 grains of powder or do a little more or less as a starting point?

Rookie re-loader in need of advice!!!

[betolatinlu]

I'd start at 19.0 grains and slowly increase in 3/10's increments.

[Sig220]

The only powder you list that is suitable for supersonic in 300BO is the 300 MP. While some may suggest 300 MP is similar to H110, I would not interchange load data between the two. I would start out at a load for a projectile that is the same approximate length at the Lupua 100gr, and closest to its weight...(I would likely use 110gr. data) but I don't know that, so I can't make suggestions. As we don't know what type weapon you are firing them from the rest would just be a gamble. I don't gamble when it comes to load data.

You might note there are loads posted in the reload area that address using 300 MP. I don't and would not suggest you just jump to the starting load for H110. You can find that information here on this board in a thread.

YMMV, but do your homework and you won't be gambling on what will, won't or might work. As a safe practice, because no 2 guns are the same, I would always start out with a reduced load from what ever source you go with. Alliant does NOT list any loads for 300BO and 300 MP

I reread my post just now and want to clarify one point.....I use 300 MP loads in my rifles. They are not published by the manufacturer but were developed from scratch and on the backs of other reloaders. I think the first load for me was 300 MP with a 110fmj. And they worked!

Good Luck