Trimming ant trying to load up .400 GNR for Irv
I bought some thin wall .38-55 to use. But it needs a little trim and blowing out out the taper. It looks a little goofy but I think they will be good plinker loads to fireform. The 200 gr. cast were running about 1200 fps from my Contender and just blowing out the taper.
We’ll have fun anyway. I did a little over (100) trimming to a bit less than 1.97”. Until I rubbed a big blister on my palm, from the knurled arbor. Good thing I’m ambidextrous, or I’d be grouchy all weekend!
![[image]](images/uploaded/202609182232526aadbc1485963.jpg)
They look goofy but the charge should fire form, blow out.
I shot some of them in my Contender. The 2.08” or so cases need a bit of trimming to get closer to the 1.97” spec. for the .400 GNR. Rather than .30-30 brass this is thin wall .38-55 Win. Should have an easier time allowing cast bullets of proper size. The .30-30 cases are all over on thickness at the case mouth. Usually they run 0.008-0.011”, the .38-55 are 0.006-0.007”. Irv has a custom .400 GNR Marlin. We have (100) rnds. to work with.
The one on the left I used an elliptical .415” sizer ball but it took lots of pressure to expand the walls. Then I sized back down to .400 GNR (10mm). But I think letting the gasses work on these new virgin cases is the best way. It works them less.
![[image]](images/uploaded/202609191908176aaedda1549e3.jpg)