First off, thanks to everyone on here who helped me out in my earlier post about building a precision AR. I used a lot of that info while putting this together.
The goal was to put together a 1000+ yard AR-15. The 264 LBC/Grendel was the obvious first choice but it comes up a little short on performance. I have a 19" CZ 527 in 264 LBC and it's a great caliber but it just has a hard time making it to 1000 yards. I wanted a bullet with a BC of at least .500 moving no slower than 2600 fps and the Grendel just isn't going to do that.
About this time my "adviser" in all things AR-15 (we call him Gunsmith-X because he wants to stay anonymous) hit me up to design a wildcat that would beat the Grendel by at least 150fps from a 20" barrel. Being more familiar with BR rifles than ARs my first thought was the 6mm Dasher. I was told that there are .473 bolt faces floating around for the AR-15 but that they weren't strong enough to run full BR pressures. That's when I stumbled onto the AR Performance 800 series bolts and extensions. It's the bolt on the right.
AR Performance doesn't sell the bolt or matching extension separately, but he happened to have a 20" 6.5 BRX barrel with the matching bolt and extension in stock. I grabbed it as quick as I could get my wallet out! From there it took a few months of stalling and putting off the project before it finally got done. I picked up a billet lower and a side charge upper then sent those plus my barrel off to Gunsmith-X to assemble the whole thing. My only real request was that it be built with a focus on precision, nothing but top quality parts. Since it's going to spend the vast majority of it's time shot off of a bench, the A2 stock made sense. I'm pretty pleased with what I got back!
Load development so far is pretty promising. Forming brass is a simple matter of taking Lapua 6mm BR cases, necking them up to 7mm then sizing them in a 7mm bushing die with a .284" bushing until the action will close on a case. I formed brass with a load of 31gr of Varget and a 123 A-max. Brass comes out 95% formed. I initially wanted to get this rifle up and running for a cow elk hunt scheduled for the last weekend of January. My initial loads were with the 130gr Accubond and IMR 8208 powder. I started at 30gr and worked up to 33.5 before I ran out of Accubonds and time last weekend. My final velocity from the 20" barrel was 2640 fps and this was far from a max charge. I couldn't get my hands on any more accubonds by this weekend so I tried the 130 gr Berger VLDs (not the new hybrids). This time I worked up to 35.5gr of IMR 8208. The results are pretty promising! I only ran 2 rounds at the max charge just trying to save time and because I was too lazy to size a few more pieces of brass.
I'm pretty pleased with the results! 2780 fps from a 20" barreled AR-15 with no pressure signs. The 2 shots that I fired at the top charge are well inside .5" at the 120 yards I was shooting. I won't have time to get the gun running for the elk hunt, but I should be able to get it dialed in after 2 more trips out. From there I'm heading straight to 1000 yards to test it. It should stay supersonic to at least 1200 yards where I shoot. The goal is to be able to hold all the shots on my 10" gong at 1000 yards. We'll see how this works out!
Andrew
The goal was to put together a 1000+ yard AR-15. The 264 LBC/Grendel was the obvious first choice but it comes up a little short on performance. I have a 19" CZ 527 in 264 LBC and it's a great caliber but it just has a hard time making it to 1000 yards. I wanted a bullet with a BC of at least .500 moving no slower than 2600 fps and the Grendel just isn't going to do that.
About this time my "adviser" in all things AR-15 (we call him Gunsmith-X because he wants to stay anonymous) hit me up to design a wildcat that would beat the Grendel by at least 150fps from a 20" barrel. Being more familiar with BR rifles than ARs my first thought was the 6mm Dasher. I was told that there are .473 bolt faces floating around for the AR-15 but that they weren't strong enough to run full BR pressures. That's when I stumbled onto the AR Performance 800 series bolts and extensions. It's the bolt on the right.
AR Performance doesn't sell the bolt or matching extension separately, but he happened to have a 20" 6.5 BRX barrel with the matching bolt and extension in stock. I grabbed it as quick as I could get my wallet out! From there it took a few months of stalling and putting off the project before it finally got done. I picked up a billet lower and a side charge upper then sent those plus my barrel off to Gunsmith-X to assemble the whole thing. My only real request was that it be built with a focus on precision, nothing but top quality parts. Since it's going to spend the vast majority of it's time shot off of a bench, the A2 stock made sense. I'm pretty pleased with what I got back!
Load development so far is pretty promising. Forming brass is a simple matter of taking Lapua 6mm BR cases, necking them up to 7mm then sizing them in a 7mm bushing die with a .284" bushing until the action will close on a case. I formed brass with a load of 31gr of Varget and a 123 A-max. Brass comes out 95% formed. I initially wanted to get this rifle up and running for a cow elk hunt scheduled for the last weekend of January. My initial loads were with the 130gr Accubond and IMR 8208 powder. I started at 30gr and worked up to 33.5 before I ran out of Accubonds and time last weekend. My final velocity from the 20" barrel was 2640 fps and this was far from a max charge. I couldn't get my hands on any more accubonds by this weekend so I tried the 130 gr Berger VLDs (not the new hybrids). This time I worked up to 35.5gr of IMR 8208. The results are pretty promising! I only ran 2 rounds at the max charge just trying to save time and because I was too lazy to size a few more pieces of brass.
I'm pretty pleased with the results! 2780 fps from a 20" barreled AR-15 with no pressure signs. The 2 shots that I fired at the top charge are well inside .5" at the 120 yards I was shooting. I won't have time to get the gun running for the elk hunt, but I should be able to get it dialed in after 2 more trips out. From there I'm heading straight to 1000 yards to test it. It should stay supersonic to at least 1200 yards where I shoot. The goal is to be able to hold all the shots on my 10" gong at 1000 yards. We'll see how this works out!
Andrew
