I'm no expert, but I'll share my opinion and experience.
First off what velocity are you getting with your 20" barrel?
I originally looked hard at the 129gr ablr due to the very reasons you did. I quickly found price per bullet and availability to be prohibitive to me. I ended up going the 123gr SST route with IMR8208XBR powder. People warn against it for use with the 129 so that's up to you.
I use my grendel out to 500 for Coues deer, if you're hunting Wyoming I assume antelope or mule deer. I have a 16" barrel and am getting 2410fps with 123gr sst. I wanted a temp. sensitive powder b/c where I live temps will go from 20's in winter to 110 in summer. I checked temp. sensitivity on my load with two 10 shot groups, one at 45*f and one at 75*. It resulted in identical average velocities of 2410fps.
Using this method of load development was quick and easy. https://www.65guys.com/10-round-load-dev...dder-test/
First off what velocity are you getting with your 20" barrel?
I originally looked hard at the 129gr ablr due to the very reasons you did. I quickly found price per bullet and availability to be prohibitive to me. I ended up going the 123gr SST route with IMR8208XBR powder. People warn against it for use with the 129 so that's up to you.
I use my grendel out to 500 for Coues deer, if you're hunting Wyoming I assume antelope or mule deer. I have a 16" barrel and am getting 2410fps with 123gr sst. I wanted a temp. sensitive powder b/c where I live temps will go from 20's in winter to 110 in summer. I checked temp. sensitivity on my load with two 10 shot groups, one at 45*f and one at 75*. It resulted in identical average velocities of 2410fps.
Using this method of load development was quick and easy. https://www.65guys.com/10-round-load-dev...dder-test/