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Discussion Starter #1
Good day,

Very new to reloading 338 Lapua, only tried a couple of different loads with this caliber, so please bear with me

Setup is as follows
Ruger precision 338LM
NF ATACR 5-25
Twist rate 1:9.375
Chamber length with scenars, 95,3mm

I have decided on the Lapua scenar 300gr to start with, will maybe go to 285 ELDM later

My question:
I loaded the following

300gr scenar
93.5gr Retumbo
TPL 93.5mm
Federal 215 match

I went to the range and shot at 300m, got a 0.28MOA group and a avg speed of 2805f/s

I am very happy with the load but a friend of mine checked quikloads and says the presure is 79000psi and should be under 60000psi

Retumbo says maximum load is 94 gr,
primer has signs of cratering, but not to excessive.

Is this load dangerous ?
 

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The Shadow
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7,597 Posts
My question:
I loaded the following

300gr scenar
93.5gr Retumbo
TPL 93.5mm
Federal 215 match

I went to the range and shot at 300m, got a 0.28MOA group and a avg speed of 2805f/s

I am very happy with the load but a friend of mine checked quikloads and says the presure is 79000psi and should be under 60000psi

Retumbo says maximum load is 94 gr,
primer has signs of cratering, but not to excessive.

Is this load dangerous ?
Yes, it is very dangerous. You are about 200fps over book velocity, and under book charges. That's a huge warning sign.
You are likely approaching proof loads, which should not be fired with any regularity.

For some info that may help you:

If you are simply going to flip a coin and guess pressures, then "signs" are better than nothing. Beyond that, "Signs" are dangerously unreliable. I've shared a bunch of pressure tests that regularly show this. Assuming you have a good chamber,good brass firing pin tollerance, etc, "signs" will tend to begin to show up with you are in the 75,000psi range.

OAL: From a quick converter, your OAL is longer than Hogdon's data. That by itself isn't an instant issue, but we don't know how much jump to lands you have, or how much they had. In the event you don't know this, any book listed OAL is typically(in this country) SAAMI minimum; rather than a "This is how you should load this" instruction. If you are either jammed or very close to the lands, then your pressures will be much higher and give you those higher velocities.

Back that animal down and stay safe, also welcome to the forum.

Cheers
 
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Discussion Starter #4
Thank you for the help DarkKer !
I will look for a lower node!!

JW Smith, luckily I only loaded 3 rounds to check, as the retumbo said i could go to 94gr.

they state a max load of 94.0C grains
pressure 53,400 CUP
velocity 2,654 f/s

yet i got 2805 f/s ...


Just for info,my OAL was 93.5 mm
which gave me a 1.7mm jump to the lands

thnx guys !
 

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The Shadow
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7,597 Posts
Here's a few more things to know about load info.

Book data doesn't tell you what YOU can load to, they merely state what THEY tested to.

The difference is in testing and lots. No one I'm aware of lists lots tested, dates tested, or if it was actually tested or simply calculated based upon the specific lot they had.

That data and pressure numbers are most likely from Hodgdon's in-house testing, since they run mostly Copper Crushers. The fundamental problem with that is their inaccuracy. It's been known by the industry for a long time, that when you are dealing with things over @ 45,000 psi, copper crushers can miss report pressure swings on the order of 25,000 psi. So what Crushers can tell you, may not be what is actually happening.

So just remember to always start low, and slowly work your way up to an accurate load. If at any time you exceed book charge weight, OR book velocity; you have exceeded SAAMI(or CIP in your case) pressures.

Cheers
 
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