Min/Max variation and compressed loads

[mungojeerie]

Ive been trying to figure out a good load for my rifle and bullet combo and have been quite confused.

Rifle: Tikka T3 .338 Win Mag
Bullet: 225gr SST Interlock
Powder: IMR 4831

I have been trying to use components that I have on hand to see if I can find something I like before spending more money exploring. Thus, the IMR 4831. I also have some RL 19 and IMR 4350 which I have read quite a few people have had luck with, so I may try them too, but for the purpose of this thread I will use the IMR 4831 as an example.

Where do most of you get your reloading data from?
for this powder and this gr of bullet I have the following min/max
69gr-73.5gr(compressed) Hodgdon manual
65gr-72gr lyman manual
57.6gr-61.6gr XXL Reloading
67gr-71gr Nosler manual

I loaded 10 rounds for a ladder test using the XXL Reloading numbers from 59gr-61.7gr and they looked normal
I poured powder into 10 using lyman numbers from 70gr-72gr and the powder was so high, I just eyeballed a bullet at its seat depth beside the case and the bullet would definitly push into the powder, especially at 72gr. it seemed like it would push into it significantly. so I just dumped them and abandoned it. I have since read that compressed rounds are a thing, and often some of the most accurate rounds come from full or slightly compressed rounds. What are your thoughts here? I was considering loading up the Lyman numbers again from 65gr-72gr at .5gr intervals and seeing how they reacted using MV as an indicator for pressure, ensuring that I didnt exceed the max MV suggested and checking each case for signs of pressure.

What are your thoughts on that? and why is there such a significant difference between sources? I understand that there will some variation between sources but the Lyman, Hodgdon and Nosler manuals all have minimums above the XXL Reloading maximum and those 3 also seem to be compressed rounds.

My apologies in advance, I am new to this and trying to understand and learn all the while keeping safe. I appreciate your help and knowledge.

 

[yomomma]

The issue is, "what does your gun like"

Powder tests are done with fixtures or "indusyrial guns".

Just found this out myself. My .308 started showing high pressure signs at aroumd 44 grains although most manuals show max at 46.

Start low, work your way up.

 

[huntingfamily]

Just another one to add to your data.
Hornady lists 58.2 - 69.8grs IMR 4831 for the 338 Win Mag and 225gr SST.

 

[Potashminer]

OP - I noticed the variation among manuals and decided they are not recipes or guarantees - I think they are the reports of what they got, using their components. Most of the manuals list the brand of case, the type of primer used, the rifle or at least the barrel that the test load was fired in - besides the powder weight and the bullet brand and weight. When you ignore those things, or presume that they are interchangeable with other brands, then you sort of venture out on your own. There is about 9 manuals on my desk - probably double that many that have been superseded by newer ones, but stored in boxes here, for some obsolete cartridges that the old books listed. I notice that Lyman, Nosler and Sierra typically list which combination they found gave best accuracy with their stuff - may or may not be relevant to you and your stuff. I notice several manuals do not indicate at all what they got for "most accurate".

Is several articles that I read - in books, or Handloader magazine, as well as on Internet forums, that suggest the home guy is simply not going to know an absolute pressure number. Is basically fooling yourself to think that looking at the fired primer, or measuring the case head expansion is going to tell you all that you need to know - that has been shown to work many times, but has also been shown NOT to work, when compared to genuine lab pressure testing. (Look up John Barsness articles, when he had various "home done" loads of his own, tested for pressure at the Western Powders lab in Miles, City, Montana - when they offered that service.) I think every manual here says to start with LOW loadings, and to work up - the manuals describe various pressure signs that a home guy might want to be familiar with.

If it matters, I have been loading for my 338 Win Mag since the early 1990's - it is a Model 70 "push feed" Winchester XTR "Sporter Magnum", that I had bought used. For some reason I settled on RL-19 powder with that one - I did work up several recipes with 225 grain Hornady bullets and lately with 225 grain Accubond bullets. Also 210 grain and 250 grain Partitions. Also 180 grain and 200 grain Ballistic Tip bullets. I also tried RL-15 and H4831, but I thought the RL-19 was what I wanted to use with the 225 grain bullets, because I also used it in my 7x57 with 150 grain Partitions. When setting a new-to-me scope, I typically fire 3 times before adjusting the scope settings - I have got multiple circa 1" groups, from the 338 Win Mag, doing that. Is just fine for what I want it for.

 

[cosmic]

If you discount XXL (which you should!), the max loads posted are within a few percent of each other - quite reasonable. The min loads are based upon some margin applied by the source - typically 5 or 10%. Your plan to use the Lyman numbers seems reasonable.
When someone on the internet says "I have read..." I interpret that to mean "read on the internet". You shouldnt put too much creedance in statements about compressed loads being best. Gun powder needs pressure to deflagrate well, so too low a charge/pressure can be problematic. However, once you get into minimum book load range, most gun powders will burn well. While you are surfing the net, you might want to read up on barrel harmonics, as they are what often dictates load performance. A fella doesnt need to be near max load to get the proper bullet residence time...