DIYguy Posted February 19, 2019 Share Posted February 19, 2019 First time for everything, at least this one for me. Worked up a series of different powder weights using AR-Comp starting with 21.7 up to 23.0 in .2 grain increments. Used MagnetoSpeed V3 for all my original chrono tests but that's different story. Now using a Labradar and a suppressor which the MagnetoSpeed would not fit so retesting different load weights as speed and grouping have changed slightly. Without the suppressor the last time I tested 23.0gr of Ar-Comp the V3 had average of 2716 fps. Made it to the range Sunday on a balmy 21 degree MN day to finally retest some loads and started with 21.8 and worked up. Got to 22.8, fired one round and gun jammed. Finally was able to take rifle apart to get to the live round in the chamber and discovered a loose primer between the case head and chamber which was keeping the bolt from going into battery. When I got back to my shop I sorted all my spent brass and found one missing the primer. Pulled my chrono reports and the one round at 22.7 clocked at 2,823 fps while 22.5 was averaging 2,762. Interesting that I've loaded up to 23.0 before without issues, might have been a fluke case/primer. When I tested the 23.0 previously it was with the V3 and it was 65 degrees out no suppressor compared to 21 degrees and suppressor. Joys of reloading Hornady brass Federal Match primers Hornady single stage press RCBS Chargemaster 1500 powder dispenser Link to comment Share on other sites More sharing options...
chevrofreak Posted February 19, 2019 Share Posted February 19, 2019 Is that a 77gr bullet? I run into pressure at 22.5gr with a 69gr BTHP, but only in my short throat 223 wylde chamber. Link to comment Share on other sites More sharing options...
DIYguy Posted February 19, 2019 Author Share Posted February 19, 2019 Oh ya....75gr Hornady BTHP for bullets with those loads. Link to comment Share on other sites More sharing options...
RGA Posted February 20, 2019 Share Posted February 20, 2019 (edited) Sounds like your primerpockets are expanding too much. How many times have you loaded this brass? Ditch the brass in this lot, start fresh and lower your load is what I'd do. Learned this the hard way a few decades ago shooting a service rifle match (AR15). A primer came out of a loose pocket during transport from mag to chamber and got stuck under my trigger group. This prevented me from finishing the match. I thought I could use this batch of expensive RWS brass one last time but I was wrong.... So since then, when I encounter a case where the primer goes in without resistance I discard it. Edited February 20, 2019 by RGA Link to comment Share on other sites More sharing options...
12glocks Posted February 20, 2019 Share Posted February 20, 2019 (edited) The velocity increases don't make sense. My first thought was could there be an error with the powder dispenser. Do you have any rounds left you can pull and weigh the charges? I pooped some primers in days past when I just started shooting AR's with carbine gas systems. Now I use mid length or rifle gas systems with an adjustable gas block and I think the bolt stays closed longer so the case can depressurise and there is less chance to poop a primer. A can would arguably increase the back pressure and unlock the bolt sooner but that does not explain the velocity increase, at least to me. Following... Edited February 20, 2019 by 12glocks syntax Link to comment Share on other sites More sharing options...
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