7/338 Lapua load help

[dinmax82]

Just started loading for my 7/338Lm. Just the neck is necked down and turned, shoulder stays the same.

Shooting the 195 Bergers.

Started with 85gr of retumbo with 215 Fed primers.

85gr primer cratered 3101 fps
86gr cratered and sticky lift 3130fps
87gr cratered and sticky lift 3170fps
88gr cratered sticky lift and completely flat primer 3205fps

I stopped there. All had ejector marks/swipes.

AI AXMC with 30" Benchmark barrel.

Thinking of trying Us869 and Rl33 next. Any suggested starting loads? Thanks!

I read that with Us869 you can pack more then retumbo but of course start with a milder load. So maybe start at 83gr for it?
No idea on the RL33

 

[Grimstod]

How full is the case? If it is not completely full then perhaps a slower or faster powder is in order.

 

[dinmax82]

How full is the case? If it is not completely full then perhaps a slower or faster powder is in order.

88gr definitely not full. I actually loaded up to 94gr but survival instincts told me to stop shooting once the primer flattened at 88gr

 

[yorketransport]

What's your case capacity on a fired case? I ran the 200gr Wildcat bullets out of a 7mm RUM and I imagine that the case capacity is very similar to your 7/338 Lapua. US869 was by far the most effective powder I tried, but it's very temp sensitive.

 

[Sniper338]

Re33 was my first thought. Drop the pressures and fill the case more

 

[dragman]

Might want to try some Peterson lapua brass. Definitely stronger than lapuas I'm running 96.5 grains of retumbo in it with 300 grain bergers.

 

[dinmax82]

Loaded up some US869, started at 85gr and went up. Primer almost completely flattened at 86gr.

Kind of disappointed as that case still had a long ways to go, even at 94 gr I could probably get 100gr in there comfortably. Speed was just 2900fps with Berger 195. It was 80 degrees out and being temp sensitive this power is a no go. No sticky bolt lift though....

Waiting on RL33 to come in and hope its a winner.

 

[338 Mollett]

For a 7/338lm the best reloading advice I can give is to order barrels by the dozen!

 

[Dusty Stevens]

Do a search on a 7mm allen magnum. You may get more info that way

 

[Zero333]

Flat primers are not the best indication of pressure.

Ejector imprint is what I look for first.

7mmRUM starting loads will be close to your Max loads.

 

[odie]

I would try contacting a man by the name of Kevin Rayhill. He developed a 7mm 338LM called the 7 Rayhill Rocket

 

[dinmax82]

Yes i looked up the Allen mag, thats where i got the idea for rl33 and us869.

Guess I'll give the us869 another shot since bolt lift wasn't sticky on it yet and primer wasn't completely flattened.

What would be the difference between a sticky bolt lift and a flattened primer to you guys be? Assume the primer is cratered either way...

 

[Zero333]

Look for ejector marks.. half moon means at least half grain over max, full moon imprint means at least 1 grain over max. This has been a reliable way for me to determine max loads with lapua brass.

I think RL-50 might be a good powder as well.

Just wondering... How much h2o capacity does a fired case have ?