Can Anyone Answer This Question?

[Jayhawker]

Shooting out of a Marlin 1894C, .357 at 50 yards off hand. 158 grain Remington SJHP and Win cases. The first groups using IMR powder with excellent results. The second groups using the same everything but with Win 296 with excellent results only the groups are consistently 2 1/2 inches to the right of the IMR groups. What makes this difference? I haven't chronoed these loads but per the books, they are very close.

Thanks.
Pete

 

[AFhack]

Powder position maybe... one of the reloading mags had an article a month or two ago that explained how where the powder sits in the case while in storage may have an effect on the accuracy of the load. I think it said that different powders reacted very differently to storage in the round.

 

[308win]

Have you tried duplicating your first group with the IMR to baseline your sights? The only thing that could explain it otherwise would be barrel harmonics. Changing comonents can often result in vertical shifts in POI.

 

[Wil Terry]

IT IS YOUR CARBINE CLEARLY TELLING YOU WHICH IS WHAT.

It is from the different barrel harmonics caused by the different burning rates and pressure levels of those two propellents.
This can be also due to the tightness and/or pressure exerted on the barrel by the front barrel band and how it reacts to the burning rates of those same two propellents.

 

[JDGray]

I wondered that myself. I sighted in my .357 with 2400, and after changing to HS6, I had to resight the gun. Both powders gave me great groups, but the windage change allways made me wonder. JDGray

 

[dtalley]

You stated that the first group is "off Hand". For accuracy testing I would suggest using a rest such as sand bags or similar.