Mysteries of the Rifle, Part III

In quick review of this series, we've taken a look at the process of trying to diagnose why my Ruger Model 77 in  the .243 Winchester caliber has had some issues with shooting both accurate and consistent groups when using both factory and hand-loaded ammunition.  Initial thoughts were that the old scope was improperly mounted or damaged and thus it was replaced, and the shooting performance of the rifle improved some.  Next, the trigger was worked on by reducing the amount of pull required to release the sear and fire the gun while also reducing creep.  This too helped increase accuracy and consistency but not to the levels we know this rifle can shoot.

A bit more of a refresher to try and clarify what I am basing my tests on and why we are examining this case; my Dad has the same make and model of rifle as I do but manufactured 2 years earlier.  Both are chambered for the .243 Winchester, have 1-in-9 inch rifling, and are primarily used for anything from small game to white-tailed deer (and possibly larger if needed).  In order to cover such a large range of animals this rifle is being used for, various bullet weights are used to match the need of the game being pursued.  A "heavier" bullet weight isn't needed for prairie dogs and a "lighter" bullet weight on a deer risks a very painful death (or worse, a non-lethal hit).  Therefore, we have a variety of handloads that my grandfather, father, and I have developed over the last 60 years or so.  Since the M77s that Dad and I have are fairly similar, we thought (perhaps erroneously) that they would shoot reasonably similar.  That was until I had a bad hunting season using this rifle back in 2008 when several deer were missed, or required two shots to be put down which I find unacceptable.  However, my Dad has his usual success with his M77 without any issues on loads or needing two rounds to put a deer down.

Again, before the one or two readers spout off with "Well, it was the shooter (i.e. YOU) that was the problem!".  I cannot dissuade you from your opinion since we cannot sit down at a range and put your opinion to the test, but I will state that I've been hunting since I was 8-years old, know that bullet placement trumps any caliber of rifle/bullet, and am probably more than a "weekend warrior" but do nowhere near enough shooting to consider myself a pro.  I'll also have a picture in a bit that might dissuade you from your opinion...but enough defending my "qualifications" if you want to call it that.

Onto the meat of this post.  A few weeks after the prairie dog shoot, I returned to my parents place to decide if there was a good hunting round I could use in a month when I would first be able to head out for white-tailed deer season.  My grandfather's notes have loads for various types of bullet design and weights; namely 70, 75, 80, 90, 95, 100, and 105-grain bullets from manufacturers Hornady, Speer, Sierra, Nosler, Winchester, and Remington (some of which have been LONG discontinued), mostly IMR or Hodgdon powders, Winchester brass, and either CCI or Winchester primers.  The previously mentioned 75-grain Hornady Hollowpoint in front of 38-grains of Hodgdon Varget powder is our favored varmint/small game load with the 95-grain Nosler Partition in front of 42-grains of Hodgdon H4831 (or H4831SC) the preferred deer load.  The time came to finally put my rifle to the test.

My test consisted of the following rounds (all with WLR primers and Winchester brass unless noted):
70-grain Nosler Ballistic-Tip in front of 45.5-grains H4350, loaded mid/late 90s by my grandfather
75-grain Hornady Hollowpoint in front of 38-grains Varget, loaded in 2000 by my grandfather
75-grain Hornady Hollowpoint in front of 38-grains Varget, loaded in 2009 by my Dad and I
85-grain Barnes Triple-shock, Federal factory ammunition (Federal brass and primers, powder unknown)

Three rounds at a time for each load with time in-between to allow the barrel to cool back to ambient temperatures, with another three rounds through my Dad's rifle and all hand-loads made from the same lot of powder, primers, and bullets and matched case weights.  Here were the results for my rifle (scale reference, from the bullseye, the first thin white circle is 1/4 inch radius, first thick white line 1/2 inch, second white line is 1 inch radius, edge of black target and white paper 1.5 inches):

The two holes in the target at the top that is cut in half (sorry, bad iPhone pic on my part) were the 75gr Hornady HP loads from my grandfather.  On target with about a 1/2 inch grouping, not bad and to be expected if I could pick off prairie dogs at 100-200 yards distance with few misses.  But then came the "New load 75gr Hor"nady hollowpoints loaded by my Dad and I.  Contrary to what the image may show, I was still aiming at the top target (center target on a grid of 3 x 3 targets), and ended up on line vertically but 2-3 inches LOW!  Huh?  Third group shot was the 85-grain Barnes Triple Shock/Federal factory load.  All were fliers and are labeled "B" on the target.  Again, these were anywhere from 1.5 to 4.5 inches LOW again AND about 2-4 inches RIGHT.  WHAT???  At this point, we started to compare my dad's shots, all of which landed in 1 to 1.5 inch groups on target and anywhere from 0 to 1 inch high.  Absolutely NO consistency between the loads and our rifles.  We also decided not to shoot the 95-grain Nosler Partition through my rifle since my Dad was getting a 1/2-inch group on target 1 inch high and the start of hunting season was around the corner.  We did decide however to use the last three rounds of 70-grain Nosler Ballistic-Tip bullets out of a box my grandfather loaded in the late 90s (the exact year escapes me, the box is at home) and were blown away by the results, a 1/2 inch group again but 3-4 inches low and 1/4 to 1/2 inch to the right.  THAT is the kind of grouping we want, but about an inch high on target (and an excellent example of good consistency but poor accuracy)!

And this brings us up to where we are at now.  My M77 is in the safe, unusable again this hunting season out of fear of missing or inhumanely bringing a deer down.  Instead, I am using my grandfathers pre-64 Winchester M70 .243 Winchester with a 100-grain Sierra bullet and have successfully dropped a doe in her tracks at 70-yards over my Thanksgiving leave from work.  We weren't able to do any further load testing since it is hunting season and I was putting a scope on a 7x57 Mauser rifle which will be a new series of posts when I bring it to the point of load development.  In the spare time we did have, my Dad and I discussed all the various elements that we had taken into account so far and came up with two more items to check:
1)  The reloading process
2)  Barrel harmonics and optimal charge weight.

So, we will be exploring these two things next with additional posts until I figure out what the best loads/bullets are for my Ruger rifle.