Well i was in the same boat a few months ago. Spend the money and build a new ELR rifle, or modify what i already have and see how far that gets me. Went with a 300 WSM throated for the Seneca 241 gn mono, with a 7.0 twist, on an existing Curtis Axiom short action in an MPA chassis. That bullet has a G1 BC over 1.0. Similar to many 375 ELR bullets. Transonic region arrives at 2,400 and subsonic at 2,600 yards.
Cost was reasonable: New magnum faced bolt, new 40 MOA rail, new barrel and dies. Total cost $1,500. Still leaves money for food and drink. It is a switchlug rifle, so dead easy to change barrels in the field.
Have to say it is easy to get hooked on ELR: Got an opportunity to shoot at a range used for ELR matches in the mountains of Namibia while on a hunting trip. Buddy of mine brought two rifles along: A semi custom 260 that is capable of 0.2” groups at a 100 and well under a MOA at 1000 in low wind. The second rifle was a very well sorted Sako TRG 42 with a factory barrel, with a combo suppressor plus muzle brake.
Started with the 260, checked the zero at 500 (dead nuts), and then went to 1,000 (figuring out the wind), and then very quickly to 1,500 yards. It was remarkable easy, but the rifle was superb and the hand loads were top quality, and the spotters were pros. Wind was predictable down in the valley. I just had to listen to the spotters, not cant the rifle and not jerk the trigger. I was purely playing the role of trigger puller, and enjoying the moment. Great fun!
Not enough elevation in the scope and base, so swithed to the 338 with the adjustable Era Tec base. It was much harder to hit the targets at 1,800 and 2,000 yards, because the wind changes as you go up the slope of the mountain. As wind speed picks up, direction changes too. 3 D topology. After 25 rounds, i had maybe 7 hits at 1,800 and exactly one hit at 2,000 yards. Never missed so often and enjoyed it that much…
One of the spotters brought a 32” 300 Winmag, 8 twist barrel and within 4 shots hit the 2,500 yard target. Weird switching wind at the top of that mountain. Nobody else could hit that target. Trick was to fire the round, load a second round, wait for the dust cloud and fire the follow-up shot before the dist could blow away. Based on how far he missed m and how rapidly the the dust cloud was moving.
I realize the smaller dust cloud kicked up by a 240 grain 30 cal will be a disadvantage in matches, when competing with 375 and 416 rifles. So be it. Wind drift will be competitive.
It will be a good learning experience.