Since you said you probably would never take a shot beyond 300 yards your choices are almost limitless.
The 6.5 Creed can get it done easily at those distances.
The 308 Win family of cartridges is viable as well, with the 260 Remington, 7mm-08, and 308 Win being among them.
14" 260 Remington...
Factory Tikka 6.5 Swede at 500 yards - 3 shots. Dan Shooting it.
I understand this is a smaller case capacity, but we didn't wait that long of a time between shots.
I am curious who likes stretching things out in terms of varmint hunting/shooting?
What are some of your favorite rigs: Chamberings, bullets, and optics?
How many have taken critters beyond a grand?
I NEVER just neck size my brass.
I always Full-Length resize my brass.
Following the instructions on your dies, will likely result in you sizing your brass more than it needs to be.
There are a lot of good videos out there on this subject
These bullets have worked good for me.
143 ELD-X at 350ish with a MV of 2818 fps
Right at 300 yards with the 143 ELD-X
175 grain ELD-X with a MV of 2900 fps (Under 250 yards)
Three elk all taken under 275 yards with the 175 grain ELD-X. One was just under 100 yards
147 grain ELD-M...
Depends on terrain and time.
I prefer prone with a bi-pod or off a pack...Whatever is the steadiest IF possible.
If I have to be higher off the ground or I am pretty sure, I cannot shoot prone, I use a tri-pod
You are welcome.
I have never used their barrels.
I typically use Bartlein, Brux, and Krieger in no order of preference.
For button barrels I use Hart, Lilja, and McGowen-In that order.
There is No BEST...
Figure out the way you want to skin the cat, and go with a optic that fits your desires.
Once you get it, you may decide that you want something different.
If you make a choice based on someone else's "best" it may or may not be "best" for you.
I would say 6mm Creed for a short action with a magazine.
I like the 6mm-284, but that doesn't fit your parameters.
6-284 at 400 yards with AB's (Just a 3-shot group, when confirming my drops).
You have got the inch loss figured out.
I shoot a lot of shorty barrels: 14-18 inches in length.
Make sure sure your can is rated for it.
You may have to change your loads, since you have changed the harmonics.
All things considered, your barrel will have more rigidity, since it is shorter.
20"...
This is a nice whitetail for the location near Story, Wyoming. They tend to be small deer there. With the help of a friend I was able to hunt, as I had a cast on my right leg at the time.
Center-grip XP-100 (Borden Alpine action/Clone XP-100) chambered in 6.5-284.
AB for first choice and the ELD-X for a close second.
ELD-X as a first choice if I am stretching things out distance wise.
I have killed mule deer and elk with the ELD-X (175 grain 7mm and 143 grain 6.5)