98Z5V Posted April 1, 2018 Report Share Posted April 1, 2018 (edited) Well, took the 12.5" Grendel out for the first time at the Spring Shoot. It performed flawlessly. Surprised us all and performed well at 500 yards - but the surprise and the shock was with how it performed at 845 yards. After getting drop data for 500 and 845 yards, I reworked the drop chart for it, and this is pretty much what it was doing: Well, to get that data, I had to play with the velocity input number to come up with the drop numbers that I actually saw out there. Shocking that the 12.5" gun was pumping out 2370 fps. The really bad thing was... ALL the primers were flat as hell. No cratered primers, but every single spent case had a flatass primer, and serious ejector swipe. Fuk, too hot. The accuracy was there, and it worked okay on the 18" gun - until I really went back and looked at some of the 18" gun's brass. Flat primers. Shiit. The reworked drop chart on the 18" gun showed that is was screamin' at 2585 fps. 3.0 mils of drop at 500 yards, and 8.2 mils of drop at 845 yards - that's 2585 fps. Damn hot. So, the rework on the loadup was shot today. I dropped a full grain, and started back up on 0.2 grain increments,and took it back out today, on the 18" gun. Went 27.5 grains, 27.7, 27.9, 28.1, and 28.3 grains. I shot some of the 28.5g that I still had loaded up, just to look at it again. I'll rework the drop chart based on a computed velocity, then take it back out at 500 yards and 850 yards, to verify what my real drops are. Then, come back and finalized the drop chart again. I'll have to do the same thing with the 12.5" gun as the 18" gun, to verify the load. "Ballistic truing" is what I've seen this called. 27.5 grains of Accurate 2520, CCI 400 primers, Hornady 6.5 Grendel brass, and Hornady 123g ELD-M projectiles - that's gonna be the load, based on what I saw today. On that 27.5g target, I straight boned up that first shot and pulled it left. I knew it when I took up on the Geissele trigger. I wish I hadn't, so I could see what that one could have really done. I only made 5 of each load for testing... Everything this morning was shot from loaded bipod, no rear bag. Edited April 1, 2018 by 98Z5V Quote Link to comment Share on other sites More sharing options...
Sisco Posted April 1, 2018 Report Share Posted April 1, 2018 This work of yours really interests me. The Grendel has the advantage of keeping with an AR 15 length cartridge. Reading about this got me thinking of an unorthodox "what the hell build" since I have a good supply of 308 Brass to resize, I am thinking of a 260 Remington SBR or a 16 in Bull barrel rifle if I don't want to mess with an ATF stamp application. I was going to talk to my FFL guy to see if we could figure out a legal way to do it. If I can find an older AR10 "B" model I would probably use that as a base to start the build, since I have a ton of Gen II magazines. Although if I do the SBR I probably will do two stamps and get a can for it at the same time. The can will be more to reduce muzzle blast from the short barrel then suppress it since it will be definitely supersonic. The 260 Remington has me intrigued to see what kind of performance I could wring out of a "shorty". Quote Link to comment Share on other sites More sharing options...
98Z5V Posted April 1, 2018 Author Report Share Posted April 1, 2018 I've been planning a .260 Rem for a long time. The 6.5 projectile is a force to be reckoned with, due to it's sectional density and the ballistic coefficient. It's incredible. I can't believe I ignored a Grendel for as many years as I have, and I'm hooked on it now. It smokes 5.56 for distance. Bad. Hell, my .308 Win 178gr load for distance needed 9.0 mils of drop at 845 yards. That's from the 20" Rem 700 AAC-SD bolt gun. The 18" Grendel smacked down the same target at 8.2 mils of drop... With less wind drift... The 12.5" Grendel got to 845 yards with 10.2 mils of drop... A little over an addition mil of drop at 845 yards, compared to a 20" barreled 1:10" twist bolt gun, shooting an optimized load. Grendel is nuts, brother. .260 Rem will be even better. All the 6.5 CM guys ignore the fact that the .260 Rem has a slight advantage over it, in case capacity, speed, and (slightly) accuracy. I was bummed to see SOCOM go 6.5CM. AMU was shooting .260 Rem for a long time, in testing. I'll have a .260 Rem AR in the future. It's a priority - as long as I can keep it higher up in the priority list. Craddock Precision will be who I get the barrel from. Quote Link to comment Share on other sites More sharing options...
jtallen83 Posted April 1, 2018 Report Share Posted April 1, 2018 I gotta quit clicking on these Grendel threads, feeling a case of grendelitis coming on...... Quote Link to comment Share on other sites More sharing options...
Sisco Posted April 1, 2018 Report Share Posted April 1, 2018 Just checked gun broker. I could get a B model AR10 slightly used for around $650 to start the build. Damn, got me thinking. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted April 1, 2018 Author Report Share Posted April 1, 2018 23 minutes ago, jtallen83 said: I gotta quit clicking on these Grendel threads, feeling a case of grendelitis coming on...... I'm here for you. When you need me. I will help you with the Grendelization of your 5.56 rifles... 19 minutes ago, Sisco said: Just checked gun broker. I could get a B model AR10 slightly used for around $650 to start the build. Damn, got me thinking. Perfect for the .260 Rem! You will probably beat me to it! Quote Link to comment Share on other sites More sharing options...
98Z5V Posted April 1, 2018 Author Report Share Posted April 1, 2018 (edited) 28 minutes ago, jtallen83 said: I gotta quit clicking on these Grendel threads, feeling a case of grendelitis coming on...... I'm telling you... you know of any other 5.56-based short barrel, at 12.5", or even close one way or the other... that's gonna reach out and hit at 845 yards with boring authority?... 10.2 mils of drop at 845 yards. I was astonished, dumbfounded, dumbstruck... Hell, I didn't know whether I'd been shot, fucked, powderburned or snakebit... Now, keep in mind, that was with the ammo that's too damn hot. I'll have a rework on that dope coming up. Really damn soon... Edited April 1, 2018 by 98Z5V Quote Link to comment Share on other sites More sharing options...
jtallen83 Posted April 1, 2018 Report Share Posted April 1, 2018 28 minutes ago, Sisco said: I could get a B model AR10 slightly used for around $650 to start the build. Damn, got me thinking. Make sure you can find the barrel first, getting tough to find AR-10 aftermarket barrels these days. $750 for the only one I can find; https://www.precisionfirearms.com/m8/260 Rem Bartlein Barrel 936--260-rem-bartlein-barrel-936.html?qty=1 Quote Link to comment Share on other sites More sharing options...
98Z5V Posted April 1, 2018 Author Report Share Posted April 1, 2018 (edited) That would be well worth the price of admission - for what you're getting in capabilities... I'm just sayin'... DPMS platform will be cheaper to get into, but you're still gonna pay for a quality .260 Rem barrel. That PF barrel will be at the very top of the heap... Call Craddock Precision... Edited April 1, 2018 by 98Z5V Quote Link to comment Share on other sites More sharing options...
Sisco Posted April 1, 2018 Report Share Posted April 1, 2018 The other option, is my standard AR 10 rifle is becoming a "safe queen", being shot less then the AR10T and the M1A, I could pick up a 260 barrel for that and be GTG. Has Nikon Monarch 4x16 glass already on it, which is really nice. $750, and done. Just have to decide between 20" and 24". Quote Link to comment Share on other sites More sharing options...
98Z5V Posted April 1, 2018 Author Report Share Posted April 1, 2018 (edited) 22", cut to 21.75". Really. There's something about 21 3/4" barrel that just performs. http://www.angelfire.com/ma3/max357/houston.html http://bulletin.accurateshooter.com/2017/04/legends-of-accuracy-the-secrets-of-the-houston-warehouse/ Edited April 1, 2018 by 98Z5V Quote Link to comment Share on other sites More sharing options...
98Z5V Posted April 1, 2018 Author Report Share Posted April 1, 2018 ^^^ THAT is my plan... Quote Link to comment Share on other sites More sharing options...
Sisco Posted April 1, 2018 Report Share Posted April 1, 2018 2 minutes ago, 98Z5V said: 22", cut to 21.75". Really. There's something about 21 3/4" barrel that just performs. http://www.angelfire.com/ma3/max357/houston.html http://bulletin.accurateshooter.com/2017/04/legends-of-accuracy-the-secrets-of-the-houston-warehouse/ That Houston warehouse story IS incredible! I got the guy here can cut it to size as well. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted April 2, 2018 Author Report Share Posted April 2, 2018 Look what I found in my inbox this morning... https://shopwilsoncombat.com/-260-Remington/products/1038/ Quote Link to comment Share on other sites More sharing options...
Sisco Posted April 2, 2018 Report Share Posted April 2, 2018 Called 10 minutes ago. Only have for DPMS style receivers. Too bad really nice barrels. I know Wilson barrels used to be standard on Rock River rifles. Might still be.. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted April 2, 2018 Author Report Share Posted April 2, 2018 You could always run a DPMS-based bolt, and save the Armalite as a spare. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted April 2, 2018 Author Report Share Posted April 2, 2018 32 minutes ago, Sisco said: Called 10 minutes ago. Only have for DPMS style receivers. Too bad really nice barrels. I know Wilson barrels used to be standard on Rock River rifles. Might still be.. Those are the Wilson Arms barrels on the RRAs, different company than Wilson Combat. I've got a few Wilson Arms barrels, and they are shooters. Quote Link to comment Share on other sites More sharing options...
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