Desert Tech 300wm older 26" 1-11 twist barrel
TBAC 338 suppressor
Norma brass
215M
Hornady 225 BTHP @ 3.485" .015" off lands
Retumbo powder
I bought the barrel used with a few hundred through it. Initially found a load at 75.9 and 2900fps(magnetospeed) that shot a solid 1/2moa if I didn't screw up. Everything I've seen from other peoples loads, quickload and Hodgdon data says I shouldn't have that much speed. Loaded in batches of 50 and 1-2 out of the 50 blew primers and ruined those pieces of brass, the rest had some cratering but were fine otherwise. I pulled down the next batch that I had already loaded and they were all actually 75.7-75.8. I've moved to a chargemaster since I loaded those.
I thought maybe I had a fast or bad batch of Retumbo so I bumped down. Shot 1 round each at 74 and 74.4 and had heavy bolt lift and ejector marks on new brass. Opened another jug of Retumbo of a different lot and shot one at 75.5 2898fps and 76 2925fps. 75.5 looked fine but 76 had light ejector marks.
76.5 of Retumbo under a 208 amax gives me 2945fps but never any sticky bolt or ejector marks.
I weighed and measured the 4 pieces of ruined brass I have and they were 214-217gr and 2.614". The other new ones I had were 217-220gr, 2.614". Checked some of my new bullets from 2 different lots and all were 225gr +/-.3gr and .3085" diameter.
The thing I'm wondering about now is I measured some fired cases and neck id is .309-.310. Is that enough clearance? During firing could the neck not be able to expand enough and be giving me excess pressure? Or is this just how my barrel is? I don't have a borescope but I'm going to yank the barrel and try to get a good look.
TBAC 338 suppressor
Norma brass
215M
Hornady 225 BTHP @ 3.485" .015" off lands
Retumbo powder
I bought the barrel used with a few hundred through it. Initially found a load at 75.9 and 2900fps(magnetospeed) that shot a solid 1/2moa if I didn't screw up. Everything I've seen from other peoples loads, quickload and Hodgdon data says I shouldn't have that much speed. Loaded in batches of 50 and 1-2 out of the 50 blew primers and ruined those pieces of brass, the rest had some cratering but were fine otherwise. I pulled down the next batch that I had already loaded and they were all actually 75.7-75.8. I've moved to a chargemaster since I loaded those.
I thought maybe I had a fast or bad batch of Retumbo so I bumped down. Shot 1 round each at 74 and 74.4 and had heavy bolt lift and ejector marks on new brass. Opened another jug of Retumbo of a different lot and shot one at 75.5 2898fps and 76 2925fps. 75.5 looked fine but 76 had light ejector marks.
76.5 of Retumbo under a 208 amax gives me 2945fps but never any sticky bolt or ejector marks.
I weighed and measured the 4 pieces of ruined brass I have and they were 214-217gr and 2.614". The other new ones I had were 217-220gr, 2.614". Checked some of my new bullets from 2 different lots and all were 225gr +/-.3gr and .3085" diameter.
The thing I'm wondering about now is I measured some fired cases and neck id is .309-.310. Is that enough clearance? During firing could the neck not be able to expand enough and be giving me excess pressure? Or is this just how my barrel is? I don't have a borescope but I'm going to yank the barrel and try to get a good look.
