Today I picked up on my load testing of Nosler Ballistic Tip projectiles in my 223 Remington and 257 Weatherby Magnum rifles.  I could have picked a better day too.  There was a heavy overcast and constant misty drizzle which at times was blowing horizontally in a strong, gusting wind.  I wondered whether it was worthwhile even setting up the chronograph in such conditions, but did so anyway.  Luckily, the shelter over the shooting bench line provided a good block to the rain and I was able to record nearly every shot.

Both my Savage 11 FCNS and Weatherby Vanguard rifles shoot more than well enough for hunting, being consistently around the MOA accuracy mark with Nosler Partitions and Accubonds.  Recently though, as I chased wild dogs on a farm where there were a number of houses close to the boundary where the dogs lurk, I moved back to the 55 grain Nosler Ballistic Tip in my Savage 223 Rem rifle.  That choice of calibre and projectile, plus a very specific shooting zone, would eliminate any risk of an exiting projectile causing a down range problem.

The 55 grain Nosler BT loads I threw together for the task shot particularly well, as they so often do.  That set me off on a bit of an interesting academic exercise to explore the effect of bullet seating depth and powder charge on accuracy and velocity.  I am sure somebody else has done this, and done it very well too, but I just wanted to play around with the concepts myself.

Last week at the range I tested a variety of seating depths for the 55 grain Nosler Ballistic Tip in my Savage 223 Rem.  That showed the rifle shot a consistent 0.6MOA with a range of seating depths and gave a best group of 0.4MOA at a 40 thou seating depth.  At this stage of the exercise I am only shooting 3 shot groups, so I did not want to get overly excited about all that.

Today, I kept the seating depth fixed at 40 thou off the lands (being an OCL of 2.350 inch in my Savage 11 FCNS) and varied the propellant charge of AR2208 (Varget in the USA).  Last week’s data had shown the rifle and BT projectile seemed to perform best with AR2208 compared to Bench Mark 2.  I yesterday’s blog I mentioned that as I neared the maximum listed charge of AR2208 I needed to use a drop tube to get a bit more load compaction in the 223 Rem cases.

The data from today’s shooting actually turned out much better than I anticipated, given I was shooting only 3 shot groups on a day of wildly varying wind gusts and drizzle.  Clearly, looking at the data given below, my sweet spot for loading the 55 grain Nosler Ballistic Tip in my Savage 11 FCNS light sporter seems to be at 40 thou off the lands and over 27.0 grains of AR2208.  For the record, I am using CCI 400 primers in Federal cases.  The Savage 11 FCNS has a 22 inch sporter weight barrel.

Also, that load is shooting almost dead-on where I want it, being exactly 1.5 inches above the point of aim at 100 yards.  It just needs one click to the left on my Swarovski 1.7-13.3×42 scope to put the group centre on the vertical.  I will load up thirty rounds and next week shoot a few 5 shot groups at the range.  The rest will be for hunting.  Conveniently, my 60 grain Nosler Partition loading shoots to almost the same POI, so I can carry a few rounds of that in case I have a chance at a boar while out after wild dogs.

My testing of the 257 Weatherby Magnum went well also, and I will report on that in the next day or two.

55 grain .224 Nosler Ballistic Tip accuracy at different propellant charges in 223 Remington

55 grain Nosler BT accuracy in a 223 Rem

 

55 grain .224 Nosler Ballistic Tip velocity at different propellant charges in 223 Remington

55 grain Nosler BT velocity  in 223 Rem