one hundred fifty thousandhs (.150) is excessive if that is the distance from the riflling to the ogive of the bullet... therefore you have a deep throat in that barrel.... but you don't say what you are shooting from it, which bullet, if you are handloading and what your COL is....

when that barrel was chambered, a reamer was used to cut it... that reamer has a set throat length on it... which is pretty much "standard"... to change the throat length you'd have to custom grind a reamer (or find one with a shorter throat already) to shorten the throat...

so, in order to correct the length of bullet ogive to rifling you'll have no other option than to either A) seat the bullet out further or B) find a longer bullet.

even if you found a reamer with a shorter throat you'd have to remove the barrel, face off the end to shorten up the chamber (short chamber the barrel) and run the new reamer in to depth and then reset headspace....

btw, i am not of the school where just a barrel will transform a gun into a cloverleaf generator... has to be right from the recoil pad to the crown IMHO.... that includes the ammunition in the chamber... and that can be the most frustrating part as the combinations of bullets, powders, primers, cases and reloading methods for 22 caliber are endless...

JR