Preface
This is part of a written compilation of a series of accuracy testing with the Thompson Center Compass bolt-action rifle, chambered in .308 Winchester, which will include load development using numerous different components and the installation and glass-bedding of a Boyd’s Prairie Hunter stock. We will establish 3 different loads using different components (each with it’s own post and video), then we will use those loads to get a baseline of accuracy with the stock that comes on the factory rifle. Once we do that, we will test those same 3 loads with the Boyd’s stock installed. Last, we’ll glass-bed the stock and test those same 3 loads again to see how the accuracy changes throughout each step of the process. In theory, we should see a linear increase in accuracy, but this is going to be a way to see first-hand if that will actually hold true.
Today we will be conducting our second test on the Thompson Center Compass in .308 Winchester in its factory configuration using the components listed below. We will be testing a relatively budget “hunting load” because this rifle is more suited for hunting than it is match shooting. So, we’re going to shoot what most deer hunters would probably be shooting through this rifle to see what kind of performance a less-expensive box of hunting ammo will give us.
WARNING: The loads shown are for informational purposes only. They are only safe in the rifle shown and may not be safe in yours. Consult appropriate load manuals prior to developing your own handloads. Risencitizen.com and its authors, do not assume any responsibility, directly or indirectly for the safety of the readers attempting to follow any instructions or perform any of the tasks shown, or the use or misuse of any information contained herein, on this website.
Components Used
- Brass- Once-Fired and Full-Length Sized Winchester .308
- Bullet- Hornady 150g Soft-Point Flat Base
- Powder- Varget 42g – 46g
- Primer- CCI Large Rifle #200
- Cartridge Overall Length- Seat to Bullet Cannelure
Loading Process/Case Preparation
Resizing
Since I am reloading once-fired brass (shot in a different rifle), we are going to full-length resize it using the RCBS Full Length Die Set (Group A) in .308 Win to make sure it will chamber in our rifle. I like to use Redding Imperial Sizing Wax when I am doing small batches of brass, but there are plenty of great lubricants out there. If you want to make your own, 1 part lanolin to 10 parts isopropyl alcohol makes for excellent homemade case lube that you can put in a spray bottle.
Tumbling, Chamfering, and Deburring
Next, we tumble the lube off in a Hornady dry media (walnut) tumbler. You can use any reloading or even non-reloading specific tumblers to complete this process. Wet tumblers tend to work even better, but the dry tumbler is just more convenient for simply getting the lube off. After we sift out all the media in a Hornady Media Sifter, we get all of our brass back on an RCBS Universal Load Block and start chamfering and deburring our brass using a Lyman Hand Tool. This will be important when we seat our bullets because flat-base bullets are much more likely to crush your case if you don’t chamfer the inside of the case mouth on your brass.
Priming and Measuring Powder
Once we got the inside and outside of the case mouths deburred, we start priming our brass. Using an RCBS Hand Primer (non-universal), all of the cases are loaded with CCI #200 large rifle primers. After that, we have to charge them with powder. In this case, Hodgdon Varget is the powder we’re using, and 5 rounds will be loaded with each powder charge (half grain increments from 42g – 46g). I like the old-school method of dumping a rough charge with an RCBS Uniflow Powder Measure and trickling up to my exact desired weight using a RCBS Trickler and Beam Scale. Gravity doesn’t lie and there are no electronics to be interfered with this way.
Bullet Seating
Lastly, we have to seat our bullets. This will be done using an RCBS Bullet Seating Die in the .308 full length group A die set. Since we are using a hunting bullet with a cannelure, we are just doing to seat the bullet down to the cannelure and call it good.
Shooting Process
The same process is followed for all load development up to this point. I usually place a Champion Redfield Style Precision Sight-In Target on a piece of anchored cardboard 100 yards away from me in a field, stretch out my Midway Shooting Mat, kick out my bipod legs, toss my ol’ sandbag/sock on mat, pull my Impact Electronic Ear Muffs out of my bag, and get comfortable behind the gun. In reality, I have to get up constantly to check camera equipment batteries and whatnot, but we’ll just pretend that part doesn’t happen.
I usually load up some sighter rounds to confirm zero and eliminate the cold bore variables that people will argue about in the comments if I don’t do it, so I do it. Once the barrel cools down, I shoot the first load, which is the lowest powder charge, feeding from the magazine as I would if I were hunting, then go mark the target for reference later and allow for the gun to cool off before the next group is put on paper. This is how all of the shooting is done to maintain consistency as much as possible.
Results
Below is a picture of the final target after the shooting is concluded and a video of the shooting with target footage. Each group is measured edge to edge with calipers and the bullet diameter is subtracted to get the final measurement.
Group Average: 1.8″
Group Average Minus Outliers: 1.4″
Please feel free to comment with any questions, and check out the YouTube channel or Facebook page for more content on this topic and others. Thank you for reading. Stay Risen.
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