300wm 20" w/ 215g and 155g hybrids

SkyScrapin

LGOWI
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Jan 31, 2010
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Chad over at LRI built me a super slick and light 300wm 20" 10 twist hunting rifle. This thing will be used from sub freezing temps to 80F, and while velocity swings are okay, they better be consistent; extreme powders are preferred.

For starters, I was dead set on using 215g Hybrids since my stash of H1000 is stacked deeper than I'll use in the next 10 years. With 92 fire forming rounds on the barrel, I'm expecting it to start settling down from a velocity perspective, allowing me to start tuning the load.

Some test load data with verified numbers:

185g Jug with 77.1g H1000 nets 2660fps very early in the barrel break in process.
215g Hybrid with 77.1g H1000 nets 2657fps coming from the last 5 round shot string, bringing the total to 92 rounds on the barrel. Important to note that my primers were flattened more than I'd prefer. It did this after the first 15 rounds too, but cleared up right after I cleaned the barrel. Suspecting that H1000 is the culprit.

It's evident that the barrel is speeding up .. pretty normal. It's also evident that H1000 is not completely burning up in the barrel before the projo exits to tube .. getting secondary ignition inside my suppressor 2 times in 92 rounds.

Since quickload isn't Mac friendly, I'm looking for suggestions:
1. Which extreme powders will give me better velocity on the 215g Hybrid? RL26? RL16?? H4831sc???
2. Looking for cleaner burning powder at the expense of bullet weight, which powder is best suited for 155g Hybrid in 20" of barrel? H4350? Varget??
 

Bandit320

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Sep 1, 2018
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Hi. I’m sure there are a lot that are interested in the 300WM, but probably very few with a 20” tube. I have one, but it is a 26” bull barrel. My data point probably won’t help you but I use H1000 with a 225 ELD-M. I would probably use RL-26 if I could find it. Good luck.

Mike
 

nn8734

nn8734
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Feb 26, 2013
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for the 180-200 class bullets, I’d perhaps try Reloader 22/26 or VVN560, they are a bit faster burning than h1000 but still good for magnums. I have read that H4831sc is also good for 160-175 class bullets in a 300 win mag and not as temp sensitive as re22.

I would think you should get at least 2800 or so when the barrel fully speeds up and you move to a faster burn rate powder. Your 2650 figure above is what folks are getting with the FGMM 308 win ammo using the 185 Jugs.

my win mag loves h1000 and 190 smks but it has a 26” tube.
 
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knuckleballz

Elk Hunter
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I'm getting just over 2800fps with reloader 26 and 215grain bergers in a 20 inch 10 twist proof carbon barrel in my falkor petra 300win mag
 
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SkyScrapin

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PV had some RL26 in stock. Giving it a try with 215s to see if I can pickup some speed. If not, going to try the Hybrid 200 and 208s.

Back ordered some H4831sc for the 155-190 class projectiles. It might be sufficient for the heavier pills considering my barrel is 20” and I’m try to get the most complete burn possible.