338LM + Retumbo Ladder

dstewart51

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Oct 19, 2011
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Lake Hughes, CA
Shot at Angeles Shooting Range Dec 29th, 2011
1600' ele, ~70 deg F, < 3 mph tail wind.

Rifle: Savage 110FCP 338LM 26" Barrel

Cartridge Details: Once fired Lapua Brass FLS to 2.190" (to 20deg shoulder), trimmed to 2.714", Federal GM215M Primer, 300gr SMK seated at 2.862" (Ogive), 3.724" (OAL) for a +0.010 Jam. Hogdon Retumbo.

Retumbo_200y_Ladder.jpg


Shot Details,
#1, 85gr 2583fps
#2, 86gr 2594fps
#3, 87gr 2614fps
#4, 88gr 2629fps
#5, 89gr 2688fps very slight primer cratering
#6, 90gr ? very slight primer cratering
#7, 91gr 2743fps slight primer cratering
#8, 92gr 2760fps slight primer cratering, very slight bolt resistance
#9, 93gr 2812fps slight primer cratering, slight bolt resistance
#10, 93.5gr 2812fps slight primer cratering, slight bolt resistance
#11, 94gr 2818fps minor primer cratering, mild bolt resistance, light extractor mark
#12, 94.5gr NOT FIRED

At 0.010" Jam I called it MAX at 94gr. We think shot #10 may have been a bit height do to my error and shots 8-11 seem to be where its at.

Today Im going back out with a charge range of 91.8gr to 93.2gr in 0.2gr increments (5 shots each) but this time -0.020" Jump. The +0.010 Jam was just to check for max safe pressure. I ran a ladder of N570 with the same specs above but it came out very different. Ill post that one up latter, time to head to the range.

Ran 40 shots through it yesterday, my shoulder is a bit sore.
 

Hoverp

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Oct 20, 2009
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Re: 338LM + Retumbo Ladder

This is my exact setup, so I am very interested!!! Have you shot the Berger 300 Hybrid?
 

fastnf

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Nov 4, 2011
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Re: 338LM + Retumbo Ladder

What distance from the barrel is your chrono?

Thanks. I just posted my first ladder in my thread. I will work on hotter loads up to 94 gr next time.
 

flashhole

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Sep 15, 2007
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Re: 338LM + Retumbo Ladder

Very nice, you definately have a sweet spot 7-11. Retumbo is not all that temperature sensitive. That being said, when I am working in the "node" I will generally settle on a charge that is above middle but below max for that node. That way I won't get any surprises on a hot day. I really like Retumbo in my 25-06 and 7mm RM with heavy bullets.
 

dstewart51

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Oct 19, 2011
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Re: 338LM + Retumbo Ladder

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: fastnf</div><div class="ubbcode-body">What distance from the barrel is your chrono?

Thanks. I just posted my first ladder in my thread. I will work on hotter loads up to 94 gr next time. </div></div>


Oh, 12-15 feet or so I think.
 

dstewart51

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Oct 19, 2011
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Re: 338LM + Retumbo Ladder

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: flashhole</div><div class="ubbcode-body">Very nice, you definately have a sweet spot 7-11. Retumbo is not all that temperature sensitive. That being said, when I am working in the "node" I will generally settle on a charge that is above middle but below max for that node. That way I won't get any surprises on a hot day. I really like Retumbo in my 25-06 and 7mm RM with heavy bullets. </div></div>

The next day I ran groups of 5 with loads from 91.8gn to 93.2gn -0.020 of the lands and it looked like the rifle liked the 92.2 gr loads the best. I need to play with the jump, from jammed to 0.10 jump with the 92.2 charge. That seems to be a very safe charge with decent velocity as well. Just need to find the ideal seating depth for the SMK now.

From the data I have already its looking like its favoring a very shallow jump or maybe even a slight jam. I have 5 each from +0.010, +0.005, ZERO, -0.005, -0.010, -0.020, -0.030, -0.050, and 3 each at -0.075 and -0.100 just to try.

I may be able to get out there before work today and see.