Would like to explore this a tad further.......
I lease a range that's 100yds, sand back & is safe certificated as penetrable targets (so paper or bunnies

) & it lists as ammunition limitations Muzzle Energy as 2030 Joules with a M Velocity of less than 718m/s (1495 Ft/Lbs & 2550 Ft/s for the imperialists

) Its used for black powder & low loaded pistol cals as well as its original 0.22 NSRA target rifle.
......... it does not say .38/ 357 / 22 or any cal .... just energy & MV?
So if I follow on from what you have done, I can develop a cheap 308 TR & a 303 SR round that is under those limits & thus OK to use on that range?
..... using led bullets & less powder load? Thus do basic full-bore training & experience shoots on that range rather than Bisley?
..... but does that not enter the territory where the case does not obscurate to form a seal in the chamber so you get back gas thru the bolt face & loading port?
Can people please discuss & I will learn from that before talking to the range owner .......
Cheers ...............

Quality control of Scottish Ethanol. & RDX/HMX
& my fav chemical is :-) 1,3,7-trimethylxanthine.......... used to kill frogs.... but widely consumed & in vast quantities by the French? Eh?