First of all, I am new here and this is my first post. I hunt a lot, mostly with archery gear, but also reload and shoot. I am a fan of the true carbine-- a rifle that shoots pistol cartridges. I hunt with a Ruger semi auto 44 mag.
I have a TNW Aero SR in 10mm. I just ordered my dies . I will only load 240 JSP's for my 44 mag. But, I cannot find anyone who makes a 10mm JSP bullet. I do see that FEDERAL offers live ammo in Vital shok with 180 JSP. Where does Federal get their components ? Where are the 10mm JSP bullets ?
First, welcome to the forum.
Second, you are correct that there really is no JSP option in a .400 slug. Some members have ordered .410" JSP's and then swaged them down to .400. I believe this was with 210 grain.
Third, in a 180-200 grain at 10mm pressure a good hard cast lead bullet will probably do everything a 180 JSP would do. I have two different 200-205 grain WFN molds. I push them full bore with no leading as long as they are sized correctly. I would not be afraid to push them out of a carbine at 1400-1500 fps, or even faster as long as pressure and load data were in line.