When to move up powder loads

[Revraz]

So I'll be reloading my first 20 rounds of my .338 LM this weekend. I'm starting out using US 869 powder, Winchester Large Rifle Primers and Sierra 250gr HPBT Match bullets.

My main question is I'll be loading the starting powder at 101 gr. At what point do I/should I increase the powder grains? Is it based on range to get more FPS?

 

[morcey2]

Get a good reloading manual (or three) and use the data located therein. It sounds like your relatively new to reloading because you're showing a fundamental misunderstanding about how to work up a load.

Also, you don't want to use a standard Large Rifle primers in a load with that much powder, especially when it's ball powder. You won't get consistent ignition.

Hodgdons web site has some good load data on it for the 338 LM. For a 250 gr bullet, they show a starting load of 101.5 gr with a max of 108 gr. Lyman 49 shows 101 - 106, so that's the range you'll be looking at.

Matt

 

[johnnyk]

I'll 2nd what Matt said. Additionally, what are your goals for this rifle/load; velocity, accuracy or both?
If the starting load (101.X) gives you the accuracy you want but not the speed, keep going. More than likely there will be another accuracy node before you reach yhe suggested max load. You may not ever reach the book max, your rifle may exhibit pressure signs before reaching the max.
You have to decide what's good enough. JohnnyK.

 

[sourdough44]

I have most of the big name manuals, plus there is web data from some powder companies. A few years back I was working up loads for a 300 WSM to use on a black bear hunt. I was only at the mid power level, still plenty to pass the 180 grn partition through the bear.

I cross reference from several reputable sources and then stick within listed data. I often use my crony to check things out.