7mm Rem Mag load work

[thatguySHM]

So I'm up against a wonderful problem to be honest. I built a 7mm Rem Mag Remage style with a 26" Criterion barrel. It had the amazingly bulky J lock firing pin assembly that I switched to a Gre-Tan fluted stainless assembly, Trigger Works trigger, DNZ one piece mount holding a Vortex Razor 3-15x44.

I have only shot 180gr ELD-M through it with RL23 powder. I started load development in March, and after just a little bit of experimenting, settled on 61.8gr for 2885 fps. I was using older mixed brass, getting an ES of 5.4, around 3/4 inch for five shots, so that's why I stopped. I have since switched to Nosler brass, and Alliant has come out with more complete data, putting the max load for a 175 at 63.8, so being me, I loaded up six rounds in .5 grain increments to 63.8, three to shoot and three to chrono with the magnetospeed. Started with my known load as a baseline, I through the second shot and it was still 3/4", probably would have one holed if not for the thrown shot. Then I fired a few other rifles, then did three more at 62.3, shot the other rifles, three 62.8, other rifles then three more at 63.3. The two middle weights hung around an inch then I got into another node with 63.3. Weather started to roll in with rain clouds on either side and and gusts of up to 40 from my 6 o'clock so I shot for rounds of 150gr Swift Scirocco II's, no luck with my random load choice, I hear they can be temperamental.

I started packing up my other rifles in case I needed to make a quick break for it, letting the 7mm cool back down, and then broke the mag speed back out, set it up, I was cooled back down so I shot the 63.3, which have me 2926 with an SD of 8.0. The rain held off, sun stayed out, so I broke the 338 AR back out so it could cool and I could do one more with my 61.8 to see what the brass change did. It slowed to 2843 with an SD of 1.4.

So the question is do I save the brass and keep the lower, more consistent charge or go after it with the higher charge that printed all three touching? I'm going to load ten or so at 63.3 and launch them at 300 at paper and then about 450 at a 8" steel plate to see how they do, but most hunting is 150 and under unless I chase the power lines or go hours north to visit the family, where shots can go as long as I can see in places.

A lot of information but I wanted to try and get it all out. I'm about 80 rounds down the tube, the barrel is broken in, doesn't foul much at all. I full length size with an RCBS custom competition sizer, switching to a Forster stem for run out, and use the Larry Willis belted magnum collet die.

Thanks everyone
SHM

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[pharmseller]

I have yet to kill an animal with either SD or ES.

Accuracy wins. Everything else is meaningless. Three shots touching at good velocity is exactly what I'm looking for.




P

 

[Elkman]

Your use of the rifle should dictate the load. Bug hole accuracy is not necessary for hunting unless you are hunting golf balls at long range. The same goes with the velocity. Few animals can tell the difference between getting killed with a bullet going 3300 fps or one going 2900. Use the one you are the most comfortable with and you will do fine.

 

[Finaddictions]

I've not seen a consistent correlation between low ES/SD's and great accuracy. The only real benefit I see for super low ES/SD's is less vertical dispersion at long range. Most hunting loads are never shot at long enough ranges to ever benefit from them. I would pick the good accuracy loads at the higher speeds and let her roll.

 

[SJB358]

Your upper load sounds great and as the load works I'd match that speed in whatever brass you have and keep trucking. That load at 2900 sounds like a butt kicker to me.