These are the loads I have been working on for the 7mm RUM:-
I'm a big fan of Berger and I built this rifle especially to benefit from thier .659 high BC offering.
- All loads are with Berger 180gr VLD's
The photo is with Retumbo - (I did a bit of research and it came up as a good mag / ultra mag powder)
- Nosler custom brass - new
- Fed GM215M primmers - Large rifle-magnum-match
- Berger 7mm 180gr VLD
.284" Ogive to the land was 3.3920" ~ my loads were seated 3.1410"
(251 tho freebore) this gave me what I felt was 'enough' bullet in the case mouth.
Picutres Shown ~ Retumbo 86gr
- this was the max charge!
Vitavori N170 89gr
faired much the same - I carefully loaded that way over the max and still got sooting (the max was 87gr - I loaded upto 89gr and still got sooting) Velocity was also very poor - around 3000fps
I was hoping for 3100 -3200fps range (the rifle has a 32" barrel and I thought the cartridge is capable of much more - my friend loads a factory rifle in 30-06 with 180gr bullets nearly upto that speed with no issues - 2990 fps)
I did beter with Vitavori N165 but its not listed on Walts data - the fastest powder he lists is H1000 at a burn rate of 118
Powder Burn Rates:-
~123 (heavy sooting)
~ 121 (very heavy sooting)
Reloader 25 ~ 120
H1000 ~ 118
IMR7828 ~ 116
Reloader 22 ~ 113 (great in my .300wm loads)
~ 112* this powder worked o.k, I wanted to try some others but I may have to go back to using it if I dont get anywhere.
With regards to the photo:-
- Crattering of the primer - is that high pressure?
- Plunger mark on the head - is that high pressure?
- Sooting to that level - is that really low pressure?
Is the fact the case is not expanding hard enough because of low pressue it is not gripping in the chamber and causing these misleading high pressure signs?