Optimize Your Firearm For Target Acquisition
Posted Jan 26th 2017 | By:
This discussion is about matching target acquisition to cartridge ballistics and then choosing optic features to complete a firearm package including any other improvements. It's a general approach to cover a wide range of interest. Certainly, a more focused discussion would be appropriate for specific objectives.
I'm a numbers guy, so I'll quantify as much as possible. Remember, there are very experienced people throughout the range of firearms, so I hope you get a chance to discuss your specific interests with some of the experts.
Starting with a basic estimate that a 10x scope is adequate for a 30" elk at 1,000 yards, we can calculate adequate scope zoom power as:
Zoom = 10*(Range in yds/1,000)*(30/Target size in inches)
Next we'll make a ballistic table for a number of popular cartridges using their corresponding Mass (grains), Ballistic Coefficient (BC) and Muzzle Velocity (MV, fps). When bullet velocity drops below sonic velocity (~1,200 fps), N/A is listed. To keep the chart simple, only MOA (100 yd. zero) and energy (ft-lbs) are listed. The table is color coded with blue for elk, green for deer, and yellow for varmint.
Combining the two charts for the 3 individual target sizes, adequate cartridge/optic packages are:
After selecting cartridge/optic requirements, consider how to distribute your budget. Generally, a higher price achieves higher quality but be careful you don't over improve one aspect without adequately balancing quality throughout your firearm package. When thinking about improving your firearm, consider the status of typical components and apply your budget to make the best overall improvement possible.
Here is a list of some rifle modifications.
Often, an enthusiast puts the "best" possible quality optic on a production rifle expecting ever better performance the more the optic costs. Instead, determine your entire firearm budget and balance the money spent on the optic with other possible improvements such as those listed above. Consider the three optics below in a case study to improve my rifle used mainly for deer and elk plus an interest in antelope:
Rifle: Reuger M77 MarkII in 7mm Rem Mag. with a
Leupold VX2 3-9x50mm with standard duplex reticle and simple capped
turrets. The trigger was too stiff and I
couldn't manage the recoil enough to hold adequate groups beyond 300
yards. Testing from a bench rest, groups
were near 1.5 MOA.
Gunsmith: He measured my trigger at over 5.5 lbs. He machined the components to provide a crisp pull at 3.75 lbs. He offered me a .270 to test, explaining his muzzle brake would reduce the recoil of the 7mm Rem Mag to that of the .270. He added two
smaller vents on the top of the brake to help balance the tendency of the rifle
to jump up off the bipod. With the brakee installed, compared to the .270, I can't tell which is more comfortable, and the rifle doesn't jump up off the bipod anymore. The package cost for the two improvements was $300.
Summary: Compared to the similar Leupold VX-3i, the OptiCo.us scope + gunsmith improvements cost $29 more. But I got the trigger and recoil problems fixed plus 1st Focal Plane, lens covers and a sunshade. The Leupold CDS option is more
sophisticated but according to chart #3, my rifle package is suitable for 800
yards requiring 20 MOA so there isn't a lot of Dope to worry about. Maybe the Leupold VX-3i excels at over 1,000 yards, but my rifle package will never be used to do that in a hunting situation. Now I have more than the 13x scope power suggested in chart #2. My original 9x power would have been less comfortable for deer at 800 yards. The gunsmith's work got my rifle shooting close to 2 MOA not using a rest compared to close to 4 MOA before his improvements. I have a little more practice to do before taking 800 yard shots. Without the improvements, I don't think that would have ever beenappropriate.
When upgrading or purchasing a rifle package, consider the performance of the entire rifle package relative to how you will use it! After completing your rifle package, time for lots of practice and training!
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