Remington Model 700 XCR Tactical Long Range 300 Win Mag

Saturday, February 19, 2011

Ladder Testing

Attempting to find the best 300 Win Mag load thru ladder testing. 

This will be my first shot at ladder testing. I have worked up two different ladder loads each with different bullets weights and powders. I'm hoping to find which load ranges my rifle likes best and fine tune further to arrive at the most accurate loads for my particular rifle. The ladder test is the best process I've found or have heard of to do this effectively. Here's a basic run down of how ladder testing works.  At the bottom I have included a link to a great video on Youtube by ryandpahl in his segment "The Road to Precision" that thoroughly explains ladder testing. I'll be sure to post an update of the results from the test. I'm hoping to get out and shoot ladders sometime next week. 

Ladder Batch #1 (Shown)
Bullet: 175 gr Sierra Match King BTHP
Powder: Hodgon H4831
Brass: Once fired range brass of various head stamps

Starting Load: 72 grains
Max Load: 76.5 grains
Ladder Increments: .5 grains
Ladder Structure: 
- 10 rounds at the starting load of 72 for sighting in at the chosen distance. Beyond 500 yards. 
- 3 rounds of each increment with bullet tips painted in a sequence of Green, Red and unpainted with Sharpie. 

For Example: 
3 rounds at 72 grains - Green 
3 rounds at 72.5 grains - Red
3 rounds at 73 grains - unpainted
 ((repeat sequence)) 

Ladder Batch #2
Bullet: 168 gr. Speer BTHP
Powder: Winchester 760 
Brass: Assorted head stamp once fired range brass

Starting Load: 64 grains
Max Load: 68 grains
Ladder Structure: .5 grain increments

The sharpie color will rub off on the target and will indicate which hole came from which shot. Naturally the shots will climb up the paper as the load increases thus creating the "ladder." 

The target is a 48" Tall x 24+" Wide blank paper on a plywood stand. The target must be large because a ladder test results become more obvious the longer the shot and for the best results with a 300 Win Mag you really need to be shooting at 500 yards or more.  I hope to set up at 600 or 700 yards if possible. 

A target is drawn or placed in the bottom quarter of the paper.  A separate steel plate or paper target is set next to the ladder target at the same distance and used to sight in the rifle using the 10 starter loads. Once the rifle is zeroed at this yardage the ladder test can begin and the shooter can take aim at the bulls-eye at the bottom of the clean ladder target. 

The shooter loads the first of the three green starters loads and fires the first shot. Afterward it's important to let the barrel cool before taking the next shot in order to eliminate changes due to barrel temperature which can be significant at distances beyond 500 yards. This process is repeated until all the round have been fired, all of which are aimed at the same bulls-eye in the bottom quarter of the ladder target.  Even though all the shots are aimed at the same point they should not impact the target all in the same place or you may need to increase the distance to the target. 

In order to limit environmental factors that may vary from shot to shot like wind you can shoot the ladder rounds in a variable order rather than 72, 72, 72   then 72.5, 72.5, 72.5 and so forth you would shoot 72, 72.5, 73, 73.5 all the way to max then start at start at the top and work down 76.5, 76, 75.5 and so forth. In the end the painted tips will rub off on the paper and it will be easy to pick out which shot is which but you will want to make a chart of notes to reference later when examining the target as shown taped to the box top in the photo.  

What you're looking for in the ladder are places where a group forms. That is to say that a small range of loads all had similar ballistics. This indicates a "sweet spot" or a load who's vibration is in the best harmony with the harmonics of your particular barrel. Once you discover these groups or sweet spots you can further develop your loads using smaller increments to fine tune and find the very best round for your rifle. 

Here is a great video by ryandpahl in his segment "the road to precision" on Youtube. He does a great job of thoroughly describing ladder testing.

Results of my first 300 Win Mag ladder test - Coming Soon

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