ASUSA Precision Rifle 1 // 13 Sep 14
Instructor: Sam
From the ASUSA Website:
"Sam is a former member of a US Department of State Diplomatic Security Group. He was deployed on multiple tours to Afghanistan and Iraq as a close protection officer, AIC and team leader for the US Diplomatic Missions to those areas and ended his career as team leader for the protective detail to the US Ambassador to Afghanistan. In non-governmental service, Sam has served as Team Leader, and Project Manager for the executive protection teams of high profile personalities all over the world." ASUSA Staff

Class started in the ASUSA classroom in their newly finished facility. We started with a bit of a show and tell session where each student discussed their rifle, optic and why they were attending the class. For most, the rifle of choice was the Remington 700 with a mid powered optic. Of the 7 people in the class 5 were shooting versions of the 700 and two were shooting Winchester Model 70 derivatives. Only one person shot a caliber other than .308 Winchester and that was a hunting rifle in .300 Win Mag.

Our instructor Sam started by saying this class was intended for those wishing to shoot better than the average hunter but not to the level of someone at a benchrest competition. He also stated the class was originally 3 days long but was broken into separate classes due to the amount of information being passed along.

We began the day with a short discussion on MIL and MOA in scopes with a chance to look at some of the different reticles in the class. Reticles ranged from simple hunting duplexes to more complex G2 reticles in a new Bushnell scope. Some of the advantages were covered and an important point was made - you must know what your adjustments are made in and what your reticle is showing you. Older scopes can have MOA adjustments on the turrets while having MIL reticles. The newer scopes in class were MIL//MIL which means the shooter only needs on set of numbers.

It is important, again, to know what your scope has for adjustments and reticle… Note that 1 MOA is actually 1.047” at 100 yards. Note that 1 MIL is 3.6” at 100 yards (or 10 cm at 100 meters so .1 MIL at 100 meters is 1 cm) - unfortunately most American minds are calibrated in inches and yards. There is actually IPHY - Inch Per Hundred Yards as well which is a true 1” at 100 yards making the math even easier and “rounder”.

Sam also touched on where your reticle is located - the first or second focal plane. First Focal Plan means the reticle will appear to change in size as you move through your different magnification settings. It will grow and shrink but will always show your reticles proper scale for range estimating purposes - 1 MOA or 1 MIL will be the same regardless of the power setting and your calculations will always be correct. One drawback is you may lose the outer portions of your reticle for bullet holdover as the disappear as you increase magnification. Second Focal Plane scopes are different in the fact the reticle remains the same throughout the power spectrum of your scope. This means there is one power where the MOA or MIL markings may be used for ranging. You will always see the full reticle but you’ll never really know what the markings represent size-wise unless set on the manufacturers designated magnification.

One final scope detail - level and angle. You should (borderline must) equip your rifle with some form of bubble level for long range shooting. If your reticle is not level (horizontally) it will cause you to miss at longer distances. Some can be had for the cost of a box of ammo while other cost closer to a case of ammo. Angle is also something to factor in to long shooting. You can measure angle or cosine - by using cosine you eliminate a step in the calculation process.

One piece mounts were also preferred because they are more sturdy than two piece mounts - with a one piece mount it adds rigidity to the overall rifle package. Most people stick with picatinny/M1913 pattern mounts to be compatible with most rings and other accessories out there.

Another interesting thing Sam mentioned was twist rate. Twist rates are important because without enough twist bullets are sometimes not stabilized when leaving the barrel. Sam mentioned that if your twist rate is not optimum for the bullet you are using, if your barrel is long enough it might make up for the “lack of” twist. So, typically, you need a faster twist rate to stabilize heavier bullets (the key is actually bullet length) - so if you’re shooting 175 grain (or heavier) bullets you would want a faster twist rate - close to 1 in 10” versus 1 in 12” if your barrel is shorter. You might be able to get away with a slower twist (1 in 12”) if your barrel is 24 inches or longer.

***Note - it is often misunderstood that you need a faster twist for heavier bullets - the fast twist requirement is actually driven by the length of the bullet - and if given a specific caliber, the bullets must get longer when they get heavier. There are great examples of this when the DoD switch to 62 grain 5.56 ammo and 1 in 7” twist in the M-16A2 from the 55 grain 1 in 12” twist M-16A1s. It wasn’t that the 62 grain bullet was so long it was the fact the accompanying tracer bullet was a whole lot longer than the 55 grain bullets it replaced. Also note that if using something like Barnes bullets which are pretty much all copper, you will have a much longer bullet for a given weight due to the lack of lead in the bullet.***

We also discussed bipods - the vast majority of bipods in the class were Harris models. Sam suggested that the lower the bipod you had on the rifle the more steady the platform would be. This proves to be true when attempting to stabilize a rifle sitting high off the ground with a long legged bipod. The Atlas bipod was suggested as more sturdy bipod than the Harris and would stand up to “loading” the bipod better than the Harris. It is also at least twice the cost of the Harris though…

Cleaning - Sam had some enlightening words on cleaning. He said using a bore guide with a one piece coated rod, from the chamber to the muzzle is the correct way to clean a precision rifle. This ensures the integrity of the barrel crown - the last thing the bullet and the accompanying gasses touch as they leave the rifle. A crown with a big nick in it will likely throw bullets as the gasses are now escaping in asymmetric pattern and will push the bullet from a straight path. Sam also said to clean only when your groups start to open up (he said somewhere between 300 and 500 rounds is where he sees this on his rifles). By shooting with a fouled barrel you keep a fairly consistent velocity which is keep to reducing the vertical spread of your group.

Load selection - generally get the load your rifle shoots well with the highest ballistic coefficient (BC). BC is essentially a measure of how well the bullet flies. Bullets with higher BCs cut the air better and will retain velocity longer, therefore dropping less. Manufacturers have discovered the shooting population is now paying attention to BCs and has started to add them to their marketing materials - and since they are in marketing materials they should be doubted - they are being used to convince you to buy their bullets and not the competitors’. To even the playing field use BCs from Brian Litz - a ballistics guru who has field tested real bullets using real guns and derived accurate BCs. In general, the heavier bullets in a given caliber have better BCs - the .308 BC for a 168 grain bullet is greater than that of a 155 grainer - 175/178 is better than 168, 208 is better than 175/178, 220 is better than 208 (these “ultra heavy” .308 bullets are typically used in .300 Win Mags due to added powder capacity to launch them at more appropriate velocities).

Other topics: Atmospheric data - you need it! The most important aspect is density altitude (DA). DA affects the way the bullet flies - the higher, the hotter, the more humid you are the better the bullet will fly because the air is less dense. Sam used a Kestrel to measure the wind speed, take the temp, figure the humidity, the barometric pressure and a couple other things. The Kestrel model he used (forgot exact number) was able to take the atmospherics and calculate the density altitude. There are other ways to find DA but they are more complicated and time consuming than the Kestrel but cheaper as Kestrels seem to run from $200 to over $700.

The first thing we did on the line was to find our scopes’ height over bore. We essentially eyeballed this with a set of calipers. To get a more precise measurement, measure the diameter of the objective bell and divide by two. Then measure the diameter of the barrel directly below the objective bell and divide that number by two. Measure the distance between the objective bell and the barrel. Take the objective bell and barrel calculations, add them together with the distance between the two and you will have your height over bore.

Once we started shooting Sam had us zero our rifles at 100 yards. Once accomplished (which was a little more time consuming than it should have been) Sam used a MagnetoSpeed chronograph to get the velocity of the rounds we were shooting. Couple this with the DA, our calculated height over bore and a ballistic calculator and folks were making hits out to 700 yards with decent regularity. Sam was using an iPhone with the Ballistic AE app designed with (maybe designed by) Brian Litz. He gave us all the dope from 200 yards out to 700 yards and we went to town shooting with a spotter helping out.

Overall Precision Rifle 1 was a good class to really dig into the basics. We ended up firing a little less than 100 rounds. I believe we would have shot a little bit more but there was a bit of difficulty getting at least one rifle zeroed at 100 yards. Always bring a rifle that is at least in the same ball park so you don’t burn ammo and waste time! I really liked this class and had a great time hitting steel out to 700 yards!