thats a bit of a fallacy as a look in any loading manual will show the .30/30 is quite a bit ahead of the x39mm on power and velocity..... also a lot of the cheap x39mm ammo out there is not that fast to begin with and some of the mil serp stuff will be erratic in velocity so any sembalence of consistancy needed to RELIABLY shoot past 150 will be gone....we got given a couple of boxes of norinco in the yellow cardboard and it was as good in x39 as it is in .223 it really went off with a bang so suggest the velocity is right up there.....we tried the cheap chinasport stuff a few years back but found a case that had excess metal at the neck that had been folded back into case and had come out upon fireing....the pressure of that must have been horrendus,lucky it was in single bakail so didnt blow up....put us off using that type of ammo fullstop....the steel cased hornady with sst projectile works very well.but still wouldnt push it past 150 myself.
Bookmarks