This data may be of interest for 220Swift users.
I keep a record of case failures relating to Winchester and Norma brass which I load with the results as described below
Winchester Brass average shots/failure : 3.2
Norma brass average shots/failure : 12.5
In order to know the case...
Correction to my insertion :
Alliant 2000-MR used with the Nosler 55gn SPBT produced a 5 shot group of 38mm @ 100m
I use a custom built shooting table and a Calder Fire Control Full-Length rest. I have owned this rifle for over 40years.
Should have stated :
Alliant 2000-MR used with the Sierra...
Have you tried the Alliant Power Pro 2000-MR powder?
I use Nosler 55gn Ballistic tip projectiles with 41gns of Alliant 2000-MR powder and Remington 91/2 primers . This resulted in a 5 shot group of 10mm @ 100m.
My rifle is a Ruger M77V with a SS 28" barrel with a 1:12 twist. There are no signs...