Wednesday, March 10, 2010

What 308 Winchester Ammo to Use During My FNAR Range Test?

The big question now is what will I shoot through my FNAR when I go to the range?  The easy part of the answer is 308 Winchester (7.62x51mm NATO).  The hard part is what weight, bullet type and brand?  To try and answer this, the next question is what will be the uses for my rifle?  I would stack the priorities like this.
  1. Primary - North American Big Game Hunting
  2. Secondary - Target Shooting
  3. Third - Predator Hunting
  4. Last - General Plinking
These priorities have made me focus my attention on finding a group of bullets with similar weight, ballistic coefficients and muzzle velocities that I can use for hunting and then a comparable match grade ammo that I can use at the range.  Also, I want to make sure that I'm not focusing on some type of exotic ammo that I couldn't find at typical gun stores or something that will cost me an arm and a leg.
Since I want to be able to find it at typical gun stores, I focused on the makers of hunting ammo that I have seen the most in places like Wal-Mart or Dick's.  This gives me the three manufacturers below to use for down selecting my list of potential ammo.
Then I tossed in Hornady because they are well known for their ammo and I specifically wanted to try their 168 grain A-MAX® match ammo.  I also tossed in some PMC Bronze 147 grain FMJ-BT because I needed something to shoot to get it on paper before I start shooting the better stuff. 
The chart below shows all the 308 ammo I considered for the initial range tests and the green highlighted shows my final selections. 
The way it worked out down selecting was that match grade ammo typically comes in two sizes, 168 and 175 grains. The 175 grain bullet is optimized for shots greater than 600 yards due to increased stability as it transitions through the transonic range. Since at this time I can not see shooting past this range and due to the greater availability of 168 grain match ammo, I focused on finding bullets that were in the 165 to 168 grain weight (except for my plinking ammo).  Since I had already decided to try out the Hornady A-MAX match ammo, all of the match ammo by these manufactures dropped off the list for the initial range test.  Then when you consider cost and select "middle of the road" hunting ammo, the list shortens to those I selected.
 
The next thing I wanted to look at was how these compare ballistically.  This will account for weight, ballistic coefficient and muzzle velocity.  To do this, I plugged the bullet data from the manufactures web sites into the Hornady Ballistics Calculator.  After compiling this data in a spreadsheet, I was able to graph it on top of each other as shown in the graph below.  The graph shows a straight line between each data point for the actual bullet data, then I had Excel curve fit a smooth line through the Hornady A-MAX data.  At 400 yards, there was only a difference of 1.7" between these impact points.  Note that the biggest drop was the Federal due to its reduced ballistic coefficient compared to the others. 
Keep in mind that even though this may seem very precise, I'm ignoring that fact that this assumes that the same 200 yard scope zero settings will work for all curves.  But for my comparative purposes, I think you will get the point. They are all very close ballistically.
When I finally get to the range (hopefully this weekend) I plan to sight in my rifle for a 200 yard zero with the Hornady A-MAX.  This means that I should be about 1.7" high at 100 yards.  Then I plan to shoot the others to see how their groups compare.  I know that some rifles may shoot different ammos to different points of impact.  I have seen this first hand on my Remington .243 with Winchester Power-Point® and Remington Core-Lokt® ammo.  The Remington continued to group high and to the right, thus I stick with the Winchester since it is always available at Wal-mart.
Keep in mind that everything I have shown with this ballistic data is all academic (theoretical) and that the best data you can get is what you will actually get shooting your rifle at the range.  I will do a follow up post with my range results at some point in the near future.
For my first trip to the range, I'm going to focus on getting the scope zeroed in and on finding out what the rifle and ammo will do at 100 yards.  This will give me a good idea on the accuracy (MOA) of the rifle and system (me included).  On future range trips, I will try to get some longer range data (200, 300 and maybe 400 yards).
This is the ammo I finally purchased for the range tests.  I have it stacked left to right in the order I plan to shoot.  I'm really hoping that the Hornady and Winchester group together well because those were the closest ballistically.


The engineer in me really likes the exactness of the tipped ammo.  Ballistic Coefficients are shown below the name.
PMC       Hornady    Winchester    Remington    Federal
.401            .475             .474             .447           .404

Also, at some point, I'm going to have to do a recheck of availablity of the ammo I like at the local gun stores.  If not, I may have to purchase several boxes to have on hand.

Update on ammo availability:  I dropped by Wal-Mart and they did not have any of these ammos I selected.  They did have the Winchester Ballistic Silvertip®, but not in the caliber and grains I needed.  I also dropped by Adventure Outdoors and again, they didn't have the grain bullets I selected.  I guess that means I will need to order several boxes and have a stock on hand.  As a backup, I'm going to throw some Winchester Powerpoint 150 grains into my selection for range testing.  It seems this ammo is the most readily available and if I got in a pinch, I would like the comfort of knowing how it would shoot in my rifle.

2 comments:

  1. I am interested in your ammo test for the FNAR 308...I have an FNAR and I shoot the Federal Ammo and am curious to see if you get the same result as I do at 100 yds. When do you expect to have the test done? thanks Dean

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  2. Dean, I have already done the initial test. I'm not real happy with the test because I don't feel as if my rest situation was very good. You can see the post by going to the following.

    http://arealmansreviews.blogspot.com/2010/04/fnar-review-third-range-test-100-yards.html

    Overall, the Federal did good compared to the others. I plan on doing more range testing next week on my FNAR with my new X7 Bulls Bag.

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