03-21-2014, 07:19 PM
My .260 Rem AR10 does the same thing to the 130gr Berger VLD's. It can put them into 5" at 1000yds. They look thrashed when I extract a live round.
My first time shooting it at 1000yds, I was in the bed of my truck, off the bipod. I shot 3 rounds into 9.25" with a wind speed shift I didn't even hold for. The mirage was boiling, so I just aimed at what I thought was the best center of a boiling black bullseye, and fired my string. I wondered if I would find any holes in the target at all as I drove out there.
I came up on it and was pleasantly surprised to find the sub-MOA group, as well as a very flat trajectory through the double-layered cardboard box (baby mattress box). I wanted to get an indicator of what my danger space was like, having shot a lot of .308 at 1000yds and farther. There was hardly any elevation difference between the entrance and exits...truly scary.
I'll have to repeat the same tests with the Grendel this spring. Might even be able to do it within the next few weeks if I can get my reloading operation set up on the new bench.
If you want to reduce a lot of the projectile gouging, make your feed ramps look like this:
![[Image: DSCF0261.jpg]](http://i1085.photobucket.com/albums/j422/LRRPF52/DSCF0261.jpg)
Steps I take when doing it:
* Pre-fit the barrel and extension in the upper receiver to see the mate-up of the extension to the feed ramps in the upper. They are rarely matching, and often bad enough that an M4 extension will lip over into an M4 upper. I use a black marker to indicate on the feed ramps what needs to be be blended in order to get a nice fit between the two. This is especially important when shooting any of the BTHP's, and even more so with the Sierra Game Kings.
* Next, I make foam plug and seal up the chamber so that no polishing compound can get into the chamber during the work.
* Then I take a flexible polishing tool head in the Dremel/Ryobi, and start polishing the ramps. I also take off the edges so that my brass necks and especially the shoulders don't bash into the sharp edges. If you look at the extensions we got with the Lilja barrels, the are the most beautiful, superb AR15 barrel extensions I have seen, and most of the work I normally do has been done when they were tumble-brushed. I'm gonna have to file a complaint with the union.
* Once I feel like I have made a little headway, I test-fit the barrel again into the upper, and look at the mate-up. I go back and forth until I am happy that the extension is blended and polished.
I do not change the angle of the feed ramps.
My first time shooting it at 1000yds, I was in the bed of my truck, off the bipod. I shot 3 rounds into 9.25" with a wind speed shift I didn't even hold for. The mirage was boiling, so I just aimed at what I thought was the best center of a boiling black bullseye, and fired my string. I wondered if I would find any holes in the target at all as I drove out there.
I came up on it and was pleasantly surprised to find the sub-MOA group, as well as a very flat trajectory through the double-layered cardboard box (baby mattress box). I wanted to get an indicator of what my danger space was like, having shot a lot of .308 at 1000yds and farther. There was hardly any elevation difference between the entrance and exits...truly scary.
I'll have to repeat the same tests with the Grendel this spring. Might even be able to do it within the next few weeks if I can get my reloading operation set up on the new bench.
If you want to reduce a lot of the projectile gouging, make your feed ramps look like this:
Steps I take when doing it:
* Pre-fit the barrel and extension in the upper receiver to see the mate-up of the extension to the feed ramps in the upper. They are rarely matching, and often bad enough that an M4 extension will lip over into an M4 upper. I use a black marker to indicate on the feed ramps what needs to be be blended in order to get a nice fit between the two. This is especially important when shooting any of the BTHP's, and even more so with the Sierra Game Kings.
* Next, I make foam plug and seal up the chamber so that no polishing compound can get into the chamber during the work.
* Then I take a flexible polishing tool head in the Dremel/Ryobi, and start polishing the ramps. I also take off the edges so that my brass necks and especially the shoulders don't bash into the sharp edges. If you look at the extensions we got with the Lilja barrels, the are the most beautiful, superb AR15 barrel extensions I have seen, and most of the work I normally do has been done when they were tumble-brushed. I'm gonna have to file a complaint with the union.
* Once I feel like I have made a little headway, I test-fit the barrel again into the upper, and look at the mate-up. I go back and forth until I am happy that the extension is blended and polished.
I do not change the angle of the feed ramps.