08-22-2018, 03:54 PM
I would caution against running any kind of load development without the assistance of a chronograph. You're missing out on too much data used in determining safety margins and trouble signs. I'm no expert in load development, but of the many posts I've read about Grendel load development, often from some of the original testers - the common thread is that it doesn't show the typical pressure signs most look for until things are too far gone because it's such a low working pressure cartridge. The Grendel MAP is 55k, but normal pressure signs (primer flattening/cratering, case web expansion, extractor swipes) don't typically show up until over 60k. The best and safest pressure indicator in Grendel is the slight drop in velocity despite increasing your charge weight. Usually only a 20-30 fps drop noticed in the next incremental step up. You will gain again on the next step after typically, but now you're over pressure and should back down again. This is all exacerbated when using a powder not usually associated with a particular cartridge like Varget, 4350, RL15, because other issues start showing up like pressure spikes at low charge levels. Be careful!
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