That sounds like a compressed load to me, and if you seated deeper than what was listed, now your causing very high pressures, and LilGun is known to spike high at times,when compressing to that degree, as long as you are on the crimp groove you should be safe, but in tern you need to lower you amount of powder, start at the min and work your way up on that load, stop before your carts start separating and sticking in the gun, make eight bullets for each load, that should display any problems if present, if that don't work, you may have undersized cylinders, as I spoke of in post originally.
I back off LilGun, due to I had some weird results using it in my 454 Casull, and it did not shoot tight enough groups out of my SRH 454 Casull, compared to W296, using Hornady 300gr XTP's...Aim small hit small. RAMbo.