This is my first post and I want to share what I have learned from building my new rifle. It is a Knights Armament SR-25 E2 PR with a U.S. Optics B-17 scope on a Spuhr mount. I hope this will help others considering a similar build.
A little background on me. I am new to long distance precision shooting and this is my first serious rifle. I am also an Engineer. As an Engineer, I complete a design before I order the first component. I try to ensure that all variables are known and solved for so that I do not find out about a problem in the middle of a project after spending a significant amount of money. This is the way I approached this rifle build.
For my purposes, I wanted a .308 semi-automatic rifle that had sub MOA accuracy and repeatability out to 900 meters, or more, while in supersonic flight. There were other requirements but for this conversation, these were the main criteria for the rifle. I decided to go with the Knights Armament SR-25 E2 PR.
After looking at several different scopes, I decided to go with the U.S. Optics B-17. The component I struggled with the most was the scope mount. I wanted a Spuhr mount because I like the rigidity, quality, low profile design and the available mounting options it provides for ACI’s and other items. I wanted a cantilever mount for eye relief and for ease of access to the charging handle but they don’t make one with a large clearance area between the rings for the U.S. Optics B-17 larger turret base. I contacted Spuhr and they recommended the 4603B. I modeled everything in my CAD program and it looked like I might have enough eye relief if the mount was as far forward as possible and the scope was mounted as far forward in the rings as possible. I could also see that the scope eyepiece would be directly above the charging handle making the charging handle difficult to access. I needed a charging handle with longer levers to get out beyond the eyepiece. I chose the Badger Ordnance GEN 3 Ambidextrous Charging Handle. I was left with the dilemma to either stay with the U.S. Optics B-17 scope and Spuhr mount and deal with some draw backs or keep the U.S. Optics scope and change the mount or keep the Spuhr mount and change the scope. I decided to stay with the U.S. Optics B-17 scope and the Spuhr mount.
Having identified the rifle and all of the components and feeling comfortable about everything interfacing well, I had the biggest hurdle of all to overcome. My wife. So I ordered everything and after a couple of months everything finally came in and I built the platform. Everything has worked out well except for the charging handle I selected and the only reason it didn’t work out was because the offset rear sight would hit the charging handle lever when the rear sight was down, otherwise the Badger Ordnance would have been fine. The levers were too thick, meaning the part where the finger goes is too far forward. I replaced it with the FALKOR MACH 10 Charging Handle and although the offset rear sight is close to the charging handle lever, it does not contact it. The FALKOR levers are thinner and wide getting it outside of the eyepiece. It’s a little awkward to get to the charging handle but I am getting used to it. I use the left side of the charging handle instead of both sides.
I broke in the barrel per Knights Armament’s procedure. I have been using the .308, 175 grain, Federal Gold Medal Sierra Matchking and have fired a total of 252 rounds through it. I have zeroed it at 100 yards and in the last 65 rounds, the rifle is holding five round groups ranging between 0.680” to 0.880”. I have a long way to go to get to where I want to be but I am enjoying this rifle and the other components. It is a very smooth rifle.
I hope this has or will be helpful to others looking to do a similar build. The build is:
Knights Armament SR-25 E2 PR M-LOK (31961)
U.S. Optics B-17 Scope with Horus H102 Reticle and Internal Eyepiece Level
Spuhr 4603B Mount
Knights Armament Precision Bipod
Knights Armament M-LOK 3” 5 Slot Rail Section
Knights Armament 45º Offset Folding Sights
VZ Grips Alien Standard Grip and 4” Inter-Lok Rail Grips
FALKOR MACH 10 Charging Handle
A little background on me. I am new to long distance precision shooting and this is my first serious rifle. I am also an Engineer. As an Engineer, I complete a design before I order the first component. I try to ensure that all variables are known and solved for so that I do not find out about a problem in the middle of a project after spending a significant amount of money. This is the way I approached this rifle build.
For my purposes, I wanted a .308 semi-automatic rifle that had sub MOA accuracy and repeatability out to 900 meters, or more, while in supersonic flight. There were other requirements but for this conversation, these were the main criteria for the rifle. I decided to go with the Knights Armament SR-25 E2 PR.
After looking at several different scopes, I decided to go with the U.S. Optics B-17. The component I struggled with the most was the scope mount. I wanted a Spuhr mount because I like the rigidity, quality, low profile design and the available mounting options it provides for ACI’s and other items. I wanted a cantilever mount for eye relief and for ease of access to the charging handle but they don’t make one with a large clearance area between the rings for the U.S. Optics B-17 larger turret base. I contacted Spuhr and they recommended the 4603B. I modeled everything in my CAD program and it looked like I might have enough eye relief if the mount was as far forward as possible and the scope was mounted as far forward in the rings as possible. I could also see that the scope eyepiece would be directly above the charging handle making the charging handle difficult to access. I needed a charging handle with longer levers to get out beyond the eyepiece. I chose the Badger Ordnance GEN 3 Ambidextrous Charging Handle. I was left with the dilemma to either stay with the U.S. Optics B-17 scope and Spuhr mount and deal with some draw backs or keep the U.S. Optics scope and change the mount or keep the Spuhr mount and change the scope. I decided to stay with the U.S. Optics B-17 scope and the Spuhr mount.
Having identified the rifle and all of the components and feeling comfortable about everything interfacing well, I had the biggest hurdle of all to overcome. My wife. So I ordered everything and after a couple of months everything finally came in and I built the platform. Everything has worked out well except for the charging handle I selected and the only reason it didn’t work out was because the offset rear sight would hit the charging handle lever when the rear sight was down, otherwise the Badger Ordnance would have been fine. The levers were too thick, meaning the part where the finger goes is too far forward. I replaced it with the FALKOR MACH 10 Charging Handle and although the offset rear sight is close to the charging handle lever, it does not contact it. The FALKOR levers are thinner and wide getting it outside of the eyepiece. It’s a little awkward to get to the charging handle but I am getting used to it. I use the left side of the charging handle instead of both sides.
I broke in the barrel per Knights Armament’s procedure. I have been using the .308, 175 grain, Federal Gold Medal Sierra Matchking and have fired a total of 252 rounds through it. I have zeroed it at 100 yards and in the last 65 rounds, the rifle is holding five round groups ranging between 0.680” to 0.880”. I have a long way to go to get to where I want to be but I am enjoying this rifle and the other components. It is a very smooth rifle.
I hope this has or will be helpful to others looking to do a similar build. The build is:
Knights Armament SR-25 E2 PR M-LOK (31961)
U.S. Optics B-17 Scope with Horus H102 Reticle and Internal Eyepiece Level
Spuhr 4603B Mount
Knights Armament Precision Bipod
Knights Armament M-LOK 3” 5 Slot Rail Section
Knights Armament 45º Offset Folding Sights
VZ Grips Alien Standard Grip and 4” Inter-Lok Rail Grips
FALKOR MACH 10 Charging Handle
