Loading Data- Dead Horse Alert!

[HKMark23]

I can't imagine this hasn't been discussed before but I havn't been able to find the thread. Anyhow, warnings abound regarding followng data tables exactly and not exceeding upper load limits. I'm preparing to run up loads for .338 LM using Hodgdon Retumbo. Hodgdon sets the uper limit for this powder, using the 250g HDY SP, at 98gr. I'm using 250g Lapua lock base.

Other manuals set the upper limit much lower, ie:

Sierra = 94.6g Retumbo for 250g MatchKing.

I've checked several manuals comparing more common powders and found similar differences. My questions are,,

1) How come?

2) Should I be reasonably safe using the Hodgdon data?
:shock: .

Thanx guys

 

[Rich McFarlane]

Re: Loading Data- Dead Horse Aert!

using the 250g HDY SP, at 98gr. I'm using 250g Lapua lock base.

Other manuals set the upper limit much lower, ie:

Sierra = 94.6g Retumbo for 250g MatchKing.

I've checked several manuals comparing more common powders and found similar differences. My questions are,,

1) How come?

Besides the worry of litagation which causes the printed works to quote loads on the conservation side, you are talking about 3 different projectiles which could have different seating depths and different ogives.
Personally I go for maximum accuracy instead of maximum power; the accurate loads are usually lighter the the full power throat burners.

2) Should I be reasonably safe using the Hodgdon data?

Sure! (they have lawyers too).

 

[dan belisle]

1) - Because they tested in different firearms or prssure testers.
2) - No. Just start in the middle of the data from the lower set of loads, and work up. You may (or may not) hit your maximum long before the books state thiers.
3) - Buy a chronograph. Without a pressure tester, this is about as close as you can get to loading to your max. If all the loading books are giving you a max of say, 2950 fps with 250 gr bullet and ### powder, then when you hit that speed, you can usually safely assume you are at the max for that cartridge. Yes, some barrels are faster then others, longer barrels are usually faster as well (but not always). Work to the averages, and you will usually be within safe limits. Oh, and ignore any magazine article that claims whizbang super duper magnum speeds for the new, and improved gorilla magnum X blast super killer this week only. Magazine writers are no different then normal folks (well, ok, maybe they are, but not in this manner), they are selling product as well as giving info, so it will be slanted as best they can. - dan

 

[HKMark23]

Thanx 4 the info. To explain further, I'm not interested in velocity for its own sake but want to develop for accuracy and was going to use this method:

http://www.frfrogspad.com/loaddev.htm

I've loaded 10 batches of cartridges in 1gr increments between 89gr and 98gr hoping to use these to start ferreting out the "sweet spot" velocities for my rifle. I may never, therefore, use the 98gr cartridges. Being new to all of this, however, my primary concern is to not generate any "mushroom clouds" during the process :shock: .