The .510 Whisper is the most fun you'll have with subsonic loads or plinking for fun...or high velocity loads with 5000 ft/lbs of energy with light bullets made for the 50 Alaska type rds.
Here's where I purchased some of the 338 Lapua mag brass.
But found a better deal with 300 Norma brass pull downs, at American Reloading.
I made mine from the above Rem 700 in 300 WM action $540 out the door for a new complete rifle,... fitted a 338 Lapua Mag bolt to the Rem 700 action, and chambered the McGowen 10 twist .510 barrel, I purchased 2 blanks with fast twists the other is 6.5 twist 338 for the 8.6 Blackout project. Modified a MDT 3.715" mag to fit the alum chassis.
Huge subsonic 1100 fps, 1002 gr bullets only lose 180 fps from 0 to 1000 yds, and arrive with 2000 ft/lbs at 1000 yds.
At just 1200 fps to 1450 fps the 620 gr APIT start to penetrate through 3/8" AR 500 armor plate at 100 yds...and detonate on targets at like pieces of 2×4 wood sending them skyward with a flash and loud bang.
There is absolutely nothing like the .510 Whisper, I have the 300 Blk, the 338 Blk, the 450 Bushmaster.
Stop thinking about it and build yourself a .510 Whisper.
It would be great for sub hunters, .510 350 gr handgun copper bullets expand at 900 fps, I ran them at 2450 fps and fairly cheap or 750 gr to 900 gr copper expanding bullets.
I used my finish reamer to make the cartridge gauge, and to make the brass go- gauge... a gunsmith will be happy to build ya one...but doing it yourself saves1/2 to 2/3 the cost, and no waiting.
If it were popular Starline could make brass for it. The fun factor is very high.
Cheap military pull downs around 45 cents ea.
I resize them, so it's actually fairly cheap to plink away.
